sqlite 3.5.1 windows source

1 files changed, 3344 insertions, 0 deletions

diff --git a/libraries/sqlite/win32/fts1.c b/libraries/sqlite/win32/fts1.c
new file mode 100755
index 0000000..5a69965
--- /dev/null
+++ b/libraries/sqlite/win32/fts1.c
@@ -0,0 +1,3344 @@
+/* fts1 has a design flaw which can lead to database corruption (see
+** below).  It is recommended not to use it any longer, instead use
+** fts3 (or higher).  If you believe that your use of fts1 is safe,
+** add -DSQLITE_ENABLE_BROKEN_FTS1=1 to your CFLAGS.
+*/
+#ifndef SQLITE_ENABLE_BROKEN_FTS1
+#error fts1 has a design flaw and has been deprecated.
+#endif
+/* The flaw is that fts1 uses the content table's unaliased rowid as
+** the unique docid.  fts1 embeds the rowid in the index it builds,
+** and expects the rowid to not change.  The SQLite VACUUM operation
+** will renumber such rowids, thereby breaking fts1.  If you are using
+** fts1 in a system which has disabled VACUUM, then you can continue
+** to use it safely.  Note that PRAGMA auto_vacuum does NOT disable
+** VACUUM, though systems using auto_vacuum are unlikely to invoke
+** VACUUM.
+**
+** fts1 should be safe even across VACUUM if you only insert documents
+** and never delete.
+*/
+
+/* The author disclaims copyright to this source code.
+ *
+ * This is an SQLite module implementing full-text search.
+ */
+
+/*
+** The code in this file is only compiled if:
+**
+**     * The FTS1 module is being built as an extension
+**       (in which case SQLITE_CORE is not defined), or
+**
+**     * The FTS1 module is being built into the core of
+**       SQLite (in which case SQLITE_ENABLE_FTS1 is defined).
+*/
+#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS1)
+
+#if defined(SQLITE_ENABLE_FTS1) && !defined(SQLITE_CORE)
+# define SQLITE_CORE 1
+#endif
+
+#include <assert.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <ctype.h>
+
+#include "fts1.h"
+#include "fts1_hash.h"
+#include "fts1_tokenizer.h"
+#include "sqlite3.h"
+#include "sqlite3ext.h"
+SQLITE_EXTENSION_INIT1
+
+
+#if 0
+# define TRACE(A)  printf A; fflush(stdout)
+#else
+# define TRACE(A)
+#endif
+
+/* utility functions */
+
+typedef struct StringBuffer {
+  int len;      /* length, not including null terminator */
+  int alloced;  /* Space allocated for s[] */ 
+  char *s;      /* Content of the string */
+} StringBuffer;
+
+static void initStringBuffer(StringBuffer *sb){
+  sb->len = 0;
+  sb->alloced = 100;
+  sb->s = malloc(100);
+  sb->s[0] = '\0';
+}
+
+static void nappend(StringBuffer *sb, const char *zFrom, int nFrom){
+  if( sb->len + nFrom >= sb->alloced ){
+    sb->alloced = sb->len + nFrom + 100;
+    sb->s = realloc(sb->s, sb->alloced+1);
+    if( sb->s==0 ){
+      initStringBuffer(sb);
+      return;
+    }
+  }
+  memcpy(sb->s + sb->len, zFrom, nFrom);
+  sb->len += nFrom;
+  sb->s[sb->len] = 0;
+}
+static void append(StringBuffer *sb, const char *zFrom){
+  nappend(sb, zFrom, strlen(zFrom));
+}
+
+/* We encode variable-length integers in little-endian order using seven bits
+ * per byte as follows:
+**
+** KEY:
+**         A = 0xxxxxxx    7 bits of data and one flag bit
+**         B = 1xxxxxxx    7 bits of data and one flag bit
+**
+**  7 bits - A
+** 14 bits - BA
+** 21 bits - BBA
+** and so on.
+*/
+
+/* We may need up to VARINT_MAX bytes to store an encoded 64-bit integer. */
+#define VARINT_MAX 10
+
+/* Write a 64-bit variable-length integer to memory starting at p[0].
+ * The length of data written will be between 1 and VARINT_MAX bytes.
+ * The number of bytes written is returned. */
+static int putVarint(char *p, sqlite_int64 v){
+  unsigned char *q = (unsigned char *) p;
+  sqlite_uint64 vu = v;
+  do{
+    *q++ = (unsigned char) ((vu & 0x7f) | 0x80);
+    vu >>= 7;
+  }while( vu!=0 );
+  q[-1] &= 0x7f;  /* turn off high bit in final byte */
+  assert( q - (unsigned char *)p <= VARINT_MAX );
+  return (int) (q - (unsigned char *)p);
+}
+
+/* Read a 64-bit variable-length integer from memory starting at p[0].
+ * Return the number of bytes read, or 0 on error.
+ * The value is stored in *v. */
+static int getVarint(const char *p, sqlite_int64 *v){
+  const unsigned char *q = (const unsigned char *) p;
+  sqlite_uint64 x = 0, y = 1;
+  while( (*q & 0x80) == 0x80 ){
+    x += y * (*q++ & 0x7f);
+    y <<= 7;
+    if( q - (unsigned char *)p >= VARINT_MAX ){  /* bad data */
+      assert( 0 );
+      return 0;
+    }
+  }
+  x += y * (*q++);
+  *v = (sqlite_int64) x;
+  return (int) (q - (unsigned char *)p);
+}
+
+static int getVarint32(const char *p, int *pi){
+ sqlite_int64 i;
+ int ret = getVarint(p, &i);
+ *pi = (int) i;
+ assert( *pi==i );
+ return ret;
+}
+
+/*** Document lists ***
+ *
+ * A document list holds a sorted list of varint-encoded document IDs.
+ *
+ * A doclist with type DL_POSITIONS_OFFSETS is stored like this:
+ *
+ * array {
+ *   varint docid;
+ *   array {
+ *     varint position;     (delta from previous position plus POS_BASE)
+ *     varint startOffset;  (delta from previous startOffset)
+ *     varint endOffset;    (delta from startOffset)
+ *   }
+ * }
+ *
+ * Here, array { X } means zero or more occurrences of X, adjacent in memory.
+ *
+ * A position list may hold positions for text in multiple columns.  A position
+ * POS_COLUMN is followed by a varint containing the index of the column for
+ * following positions in the list.  Any positions appearing before any
+ * occurrences of POS_COLUMN are for column 0.
+ *
+ * A doclist with type DL_POSITIONS is like the above, but holds only docids
+ * and positions without offset information.
+ *
+ * A doclist with type DL_DOCIDS is like the above, but holds only docids
+ * without positions or offset information.
+ *
+ * On disk, every document list has positions and offsets, so we don't bother
+ * to serialize a doclist's type.
+ * 
+ * We don't yet delta-encode document IDs; doing so will probably be a
+ * modest win.
+ *
+ * NOTE(shess) I've thought of a slightly (1%) better offset encoding.
+ * After the first offset, estimate the next offset by using the
+ * current token position and the previous token position and offset,
+ * offset to handle some variance.  So the estimate would be
+ * (iPosition*w->iStartOffset/w->iPosition-64), which is delta-encoded
+ * as normal.  Offsets more than 64 chars from the estimate are
+ * encoded as the delta to the previous start offset + 128.  An
+ * additional tiny increment can be gained by using the end offset of
+ * the previous token to make the estimate a tiny bit more precise.
+*/
+
+/* It is not safe to call isspace(), tolower(), or isalnum() on
+** hi-bit-set characters.  This is the same solution used in the
+** tokenizer.
+*/
+/* TODO(shess) The snippet-generation code should be using the
+** tokenizer-generated tokens rather than doing its own local
+** tokenization.
+*/
+/* TODO(shess) Is __isascii() a portable version of (c&0x80)==0? */
+static int safe_isspace(char c){
+  return (c&0x80)==0 ? isspace(c) : 0;
+}
+static int safe_tolower(char c){
+  return (c&0x80)==0 ? tolower(c) : c;
+}
+static int safe_isalnum(char c){
+  return (c&0x80)==0 ? isalnum(c) : 0;
+}
+
+typedef enum DocListType {
+  DL_DOCIDS,              /* docids only */
+  DL_POSITIONS,           /* docids + positions */
+  DL_POSITIONS_OFFSETS    /* docids + positions + offsets */
+} DocListType;
+
+/*
+** By default, only positions and not offsets are stored in the doclists.
+** To change this so that offsets are stored too, compile with
+**
+**          -DDL_DEFAULT=DL_POSITIONS_OFFSETS
+**
+*/
+#ifndef DL_DEFAULT
+# define DL_DEFAULT DL_POSITIONS
+#endif
+
+typedef struct DocList {
+  char *pData;
+  int nData;
+  DocListType iType;
+  int iLastColumn;    /* the last column written */
+  int iLastPos;       /* the last position written */
+  int iLastOffset;    /* the last start offset written */
+} DocList;
+
+enum {
+  POS_END = 0,        /* end of this position list */
+  POS_COLUMN,         /* followed by new column number */
+  POS_BASE
+};
+
+/* Initialize a new DocList to hold the given data. */
+static void docListInit(DocList *d, DocListType iType,
+                        const char *pData, int nData){
+  d->nData = nData;
+  if( nData>0 ){
+    d->pData = malloc(nData);
+    memcpy(d->pData, pData, nData);
+  } else {
+    d->pData = NULL;
+  }
+  d->iType = iType;
+  d->iLastColumn = 0;
+  d->iLastPos = d->iLastOffset = 0;
+}
+
+/* Create a new dynamically-allocated DocList. */
+static DocList *docListNew(DocListType iType){
+  DocList *d = (DocList *) malloc(sizeof(DocList));
+  docListInit(d, iType, 0, 0);
+  return d;
+}
+
+static void docListDestroy(DocList *d){
+  free(d->pData);
+#ifndef NDEBUG
+  memset(d, 0x55, sizeof(*d));
+#endif
+}
+
+static void docListDelete(DocList *d){
+  docListDestroy(d);
+  free(d);
+}
+
+static char *docListEnd(DocList *d){
+  return d->pData + d->nData;
+}
+
+/* Append a varint to a DocList's data. */
+static void appendVarint(DocList *d, sqlite_int64 i){
+  char c[VARINT_MAX];
+  int n = putVarint(c, i);
+  d->pData = realloc(d->pData, d->nData + n);
+  memcpy(d->pData + d->nData, c, n);
+  d->nData += n;
+}
+
+static void docListAddDocid(DocList *d, sqlite_int64 iDocid){
+  appendVarint(d, iDocid);
+  if( d->iType>=DL_POSITIONS ){
+    appendVarint(d, POS_END);  /* initially empty position list */
+    d->iLastColumn = 0;
+    d->iLastPos = d->iLastOffset = 0;
+  }
+}
+
+/* helper function for docListAddPos and docListAddPosOffset */
+static void addPos(DocList *d, int iColumn, int iPos){
+  assert( d->nData>0 );
+  --d->nData;  /* remove previous terminator */
+  if( iColumn!=d->iLastColumn ){
+    assert( iColumn>d->iLastColumn );
+    appendVarint(d, POS_COLUMN);
+    appendVarint(d, iColumn);
+    d->iLastColumn = iColumn;
+    d->iLastPos = d->iLastOffset = 0;
+  }
+  assert( iPos>=d->iLastPos );
+  appendVarint(d, iPos-d->iLastPos+POS_BASE);
+  d->iLastPos = iPos;
+}
+
+/* Add a position to the last position list in a doclist. */
+static void docListAddPos(DocList *d, int iColumn, int iPos){
+  assert( d->iType==DL_POSITIONS );
+  addPos(d, iColumn, iPos);
+  appendVarint(d, POS_END);  /* add new terminator */
+}
+
+/*
+** Add a position and starting and ending offsets to a doclist.
+**
+** If the doclist is setup to handle only positions, then insert
+** the position only and ignore the offsets.
+*/
+static void docListAddPosOffset(
+  DocList *d,             /* Doclist under construction */
+  int iColumn,            /* Column the inserted term is part of */
+  int iPos,               /* Position of the inserted term */
+  int iStartOffset,       /* Starting offset of inserted term */
+  int iEndOffset          /* Ending offset of inserted term */
+){
+  assert( d->iType>=DL_POSITIONS );
+  addPos(d, iColumn, iPos);
+  if( d->iType==DL_POSITIONS_OFFSETS ){
+    assert( iStartOffset>=d->iLastOffset );
+    appendVarint(d, iStartOffset-d->iLastOffset);
+    d->iLastOffset = iStartOffset;
+    assert( iEndOffset>=iStartOffset );
+    appendVarint(d, iEndOffset-iStartOffset);
+  }
+  appendVarint(d, POS_END);  /* add new terminator */
+}
+
+/*
+** A DocListReader object is a cursor into a doclist.  Initialize
+** the cursor to the beginning of the doclist by calling readerInit().
+** Then use routines
+**
+**      peekDocid()
+**      readDocid()
+**      readPosition()
+**      skipPositionList()
+**      and so forth...
+**
+** to read information out of the doclist.  When we reach the end
+** of the doclist, atEnd() returns TRUE.
+*/
+typedef struct DocListReader {
+  DocList *pDoclist;  /* The document list we are stepping through */
+  char *p;            /* Pointer to next unread byte in the doclist */
+  int iLastColumn;
+  int iLastPos;  /* the last position read, or -1 when not in a position list */
+} DocListReader;
+
+/*
+** Initialize the DocListReader r to point to the beginning of pDoclist.
+*/
+static void readerInit(DocListReader *r, DocList *pDoclist){
+  r->pDoclist = pDoclist;
+  if( pDoclist!=NULL ){
+    r->p = pDoclist->pData;
+  }
+  r->iLastColumn = -1;
+  r->iLastPos = -1;
+}
+
+/*
+** Return TRUE if we have reached then end of pReader and there is
+** nothing else left to read.
+*/
+static int atEnd(DocListReader *pReader){
+  return pReader->pDoclist==0 || (pReader->p >= docListEnd(pReader->pDoclist));
+}
+
+/* Peek at the next docid without advancing the read pointer. 
+*/
+static sqlite_int64 peekDocid(DocListReader *pReader){
+  sqlite_int64 ret;
+  assert( !atEnd(pReader) );
+  assert( pReader->iLastPos==-1 );
+  getVarint(pReader->p, &ret);
+  return ret;
+}
+
+/* Read the next docid.   See also nextDocid().
+*/
+static sqlite_int64 readDocid(DocListReader *pReader){
+  sqlite_int64 ret;
+  assert( !atEnd(pReader) );
+  assert( pReader->iLastPos==-1 );
+  pReader->p += getVarint(pReader->p, &ret);
+  if( pReader->pDoclist->iType>=DL_POSITIONS ){
+    pReader->iLastColumn = 0;
+    pReader->iLastPos = 0;
+  }
+  return ret;
+}
+
+/* Read the next position and column index from a position list.
+ * Returns the position, or -1 at the end of the list. */
+static int readPosition(DocListReader *pReader, int *iColumn){
+  int i;
+  int iType = pReader->pDoclist->iType;
+
+  if( pReader->iLastPos==-1 ){
+    return -1;
+  }
+  assert( !atEnd(pReader) );
+
+  if( iType<DL_POSITIONS ){
+    return -1;
+  }
+  pReader->p += getVarint32(pReader->p, &i);
+  if( i==POS_END ){
+    pReader->iLastColumn = pReader->iLastPos = -1;
+    *iColumn = -1;
+    return -1;
+  }
+  if( i==POS_COLUMN ){
+    pReader->p += getVarint32(pReader->p, &pReader->iLastColumn);
+    pReader->iLastPos = 0;
+    pReader->p += getVarint32(pReader->p, &i);
+    assert( i>=POS_BASE );
+  }
+  pReader->iLastPos += ((int) i)-POS_BASE;
+  if( iType>=DL_POSITIONS_OFFSETS ){
+    /* Skip over offsets, ignoring them for now. */
+    int iStart, iEnd;
+    pReader->p += getVarint32(pReader->p, &iStart);
+    pReader->p += getVarint32(pReader->p, &iEnd);
+  }
+  *iColumn = pReader->iLastColumn;
+  return pReader->iLastPos;
+}
+
+/* Skip past the end of a position list. */
+static void skipPositionList(DocListReader *pReader){
+  DocList *p = pReader->pDoclist;
+  if( p && p->iType>=DL_POSITIONS ){
+    int iColumn;
+    while( readPosition(pReader, &iColumn)!=-1 ){}
+  }
+}
+
+/* Skip over a docid, including its position list if the doclist has
+ * positions. */
+static void skipDocument(DocListReader *pReader){
+  readDocid(pReader);
+  skipPositionList(pReader);
+}
+
+/* Skip past all docids which are less than [iDocid].  Returns 1 if a docid
+ * matching [iDocid] was found.  */
+static int skipToDocid(DocListReader *pReader, sqlite_int64 iDocid){
+  sqlite_int64 d = 0;
+  while( !atEnd(pReader) && (d=peekDocid(pReader))<iDocid ){
+    skipDocument(pReader);
+  }
+  return !atEnd(pReader) && d==iDocid;
+}
+
+/* Return the first document in a document list.
+*/
+static sqlite_int64 firstDocid(DocList *d){
+  DocListReader r;
+  readerInit(&r, d);
+  return readDocid(&r);
+}
+
+#ifdef SQLITE_DEBUG
+/*
+** This routine is used for debugging purpose only.
+**
+** Write the content of a doclist to standard output.
+*/
+static void printDoclist(DocList *p){
+  DocListReader r;
+  const char *zSep = "";
+
+  readerInit(&r, p);
+  while( !atEnd(&r) ){
+    sqlite_int64 docid = readDocid(&r);
+    if( docid==0 ){
+      skipPositionList(&r);
+      continue;
+    }
+    printf("%s%lld", zSep, docid);
+    zSep =  ",";
+    if( p->iType>=DL_POSITIONS ){
+      int iPos, iCol;
+      const char *zDiv = "";
+      printf("(");
+      while( (iPos = readPosition(&r, &iCol))>=0 ){
+        printf("%s%d:%d", zDiv, iCol, iPos);
+        zDiv = ":";
+      }
+      printf(")");
+    }
+  }
+  printf("\n");
+  fflush(stdout);
+}
+#endif /* SQLITE_DEBUG */
+
+/* Trim the given doclist to contain only positions in column
+ * [iRestrictColumn]. */
+static void docListRestrictColumn(DocList *in, int iRestrictColumn){
+  DocListReader r;
+  DocList out;
+
+  assert( in->iType>=DL_POSITIONS );
+  readerInit(&r, in);
+  docListInit(&out, DL_POSITIONS, NULL, 0);
+
+  while( !atEnd(&r) ){
+    sqlite_int64 iDocid = readDocid(&r);
+    int iPos, iColumn;
+
+    docListAddDocid(&out, iDocid);
+    while( (iPos = readPosition(&r, &iColumn)) != -1 ){
+      if( iColumn==iRestrictColumn ){
+        docListAddPos(&out, iColumn, iPos);
+      }
+    }
+  }
+
+  docListDestroy(in);
+  *in = out;
+}
+
+/* Trim the given doclist by discarding any docids without any remaining
+ * positions. */
+static void docListDiscardEmpty(DocList *in) {
+  DocListReader r;
+  DocList out;
+
+  /* TODO: It would be nice to implement this operation in place; that
+   * could save a significant amount of memory in queries with long doclists. */
+  assert( in->iType>=DL_POSITIONS );
+  readerInit(&r, in);
+  docListInit(&out, DL_POSITIONS, NULL, 0);
+
+  while( !atEnd(&r) ){
+    sqlite_int64 iDocid = readDocid(&r);
+    int match = 0;
+    int iPos, iColumn;
+    while( (iPos = readPosition(&r, &iColumn)) != -1 ){
+      if( !match ){
+        docListAddDocid(&out, iDocid);
+        match = 1;
+      }
+      docListAddPos(&out, iColumn, iPos);
+    }
+  }
+
+  docListDestroy(in);
+  *in = out;
+}
+
+/* Helper function for docListUpdate() and docListAccumulate().
+** Splices a doclist element into the doclist represented by r,
+** leaving r pointing after the newly spliced element.
+*/
+static void docListSpliceElement(DocListReader *r, sqlite_int64 iDocid,
+                                 const char *pSource, int nSource){
+  DocList *d = r->pDoclist;
+  char *pTarget;
+  int nTarget, found;
+
+  found = skipToDocid(r, iDocid);
+
+  /* Describe slice in d to place pSource/nSource. */
+  pTarget = r->p;
+  if( found ){
+    skipDocument(r);
+    nTarget = r->p-pTarget;
+  }else{
+    nTarget = 0;
+  }
+
+  /* The sense of the following is that there are three possibilities.
+  ** If nTarget==nSource, we should not move any memory nor realloc.
+  ** If nTarget>nSource, trim target and realloc.
+  ** If nTarget<nSource, realloc then expand target.
+  */
+  if( nTarget>nSource ){
+    memmove(pTarget+nSource, pTarget+nTarget, docListEnd(d)-(pTarget+nTarget));
+  }
+  if( nTarget!=nSource ){
+    int iDoclist = pTarget-d->pData;
+    d->pData = realloc(d->pData, d->nData+nSource-nTarget);
+    pTarget = d->pData+iDoclist;
+  }
+  if( nTarget<nSource ){
+    memmove(pTarget+nSource, pTarget+nTarget, docListEnd(d)-(pTarget+nTarget));
+  }
+
+  memcpy(pTarget, pSource, nSource);
+  d->nData += nSource-nTarget;
+  r->p = pTarget+nSource;
+}
+
+/* Insert/update pUpdate into the doclist. */
+static void docListUpdate(DocList *d, DocList *pUpdate){
+  DocListReader reader;
+
+  assert( d!=NULL && pUpdate!=NULL );
+  assert( d->iType==pUpdate->iType);
+
+  readerInit(&reader, d);
+  docListSpliceElement(&reader, firstDocid(pUpdate),
+                       pUpdate->pData, pUpdate->nData);
+}
+
+/* Propagate elements from pUpdate to pAcc, overwriting elements with
+** matching docids.
+*/
+static void docListAccumulate(DocList *pAcc, DocList *pUpdate){
+  DocListReader accReader, updateReader;
+
+  /* Handle edge cases where one doclist is empty. */
+  assert( pAcc!=NULL );
+  if( pUpdate==NULL || pUpdate->nData==0 ) return;
+  if( pAcc->nData==0 ){
+    pAcc->pData = malloc(pUpdate->nData);
+    memcpy(pAcc->pData, pUpdate->pData, pUpdate->nData);
+    pAcc->nData = pUpdate->nData;
+    return;
+  }
+
+  readerInit(&accReader, pAcc);
+  readerInit(&updateReader, pUpdate);
+
+  while( !atEnd(&updateReader) ){
+    char *pSource = updateReader.p;
+    sqlite_int64 iDocid = readDocid(&updateReader);
+    skipPositionList(&updateReader);
+    docListSpliceElement(&accReader, iDocid, pSource, updateReader.p-pSource);
+  }
+}
+
+/*
+** Read the next docid off of pIn.  Return 0 if we reach the end.
+*
+* TODO: This assumes that docids are never 0, but they may actually be 0 since
+* users can choose docids when inserting into a full-text table.  Fix this.
+*/
+static sqlite_int64 nextDocid(DocListReader *pIn){
+  skipPositionList(pIn);
+  return atEnd(pIn) ? 0 : readDocid(pIn);
+}
+
+/*
+** pLeft and pRight are two DocListReaders that are pointing to
+** positions lists of the same document: iDocid. 
+**
+** If there are no instances in pLeft or pRight where the position
+** of pLeft is one less than the position of pRight, then this
+** routine adds nothing to pOut.
+**
+** If there are one or more instances where positions from pLeft
+** are exactly one less than positions from pRight, then add a new
+** document record to pOut.  If pOut wants to hold positions, then
+** include the positions from pRight that are one more than a
+** position in pLeft.  In other words:  pRight.iPos==pLeft.iPos+1.
+**
+** pLeft and pRight are left pointing at the next document record.
+*/
+static void mergePosList(
+  DocListReader *pLeft,    /* Left position list */
+  DocListReader *pRight,   /* Right position list */
+  sqlite_int64 iDocid,     /* The docid from pLeft and pRight */
+  DocList *pOut            /* Write the merged document record here */
+){
+  int iLeftCol, iLeftPos = readPosition(pLeft, &iLeftCol);
+  int iRightCol, iRightPos = readPosition(pRight, &iRightCol);
+  int match = 0;
+
+  /* Loop until we've reached the end of both position lists. */
+  while( iLeftPos!=-1 && iRightPos!=-1 ){
+    if( iLeftCol==iRightCol && iLeftPos+1==iRightPos ){
+      if( !match ){
+        docListAddDocid(pOut, iDocid);
+        match = 1;
+      }
+      if( pOut->iType>=DL_POSITIONS ){
+        docListAddPos(pOut, iRightCol, iRightPos);
+      }
+      iLeftPos = readPosition(pLeft, &iLeftCol);
+      iRightPos = readPosition(pRight, &iRightCol);
+    }else if( iRightCol<iLeftCol ||
+              (iRightCol==iLeftCol && iRightPos<iLeftPos+1) ){
+      iRightPos = readPosition(pRight, &iRightCol);
+    }else{
+      iLeftPos = readPosition(pLeft, &iLeftCol);
+    }
+  }
+  if( iLeftPos>=0 ) skipPositionList(pLeft);
+  if( iRightPos>=0 ) skipPositionList(pRight);
+}
+
+/* We have two doclists:  pLeft and pRight.
+** Write the phrase intersection of these two doclists into pOut.
+**
+** A phrase intersection means that two documents only match
+** if pLeft.iPos+1==pRight.iPos.
+**
+** The output pOut may or may not contain positions.  If pOut
+** does contain positions, they are the positions of pRight.
+*/
+static void docListPhraseMerge(
+  DocList *pLeft,    /* Doclist resulting from the words on the left */
+  DocList *pRight,   /* Doclist for the next word to the right */
+  DocList *pOut      /* Write the combined doclist here */
+){
+  DocListReader left, right;
+  sqlite_int64 docidLeft, docidRight;
+
+  readerInit(&left, pLeft);
+  readerInit(&right, pRight);
+  docidLeft = nextDocid(&left);
+  docidRight = nextDocid(&right);
+
+  while( docidLeft>0 && docidRight>0 ){
+    if( docidLeft<docidRight ){
+      docidLeft = nextDocid(&left);
+    }else if( docidRight<docidLeft ){
+      docidRight = nextDocid(&right);
+    }else{
+      mergePosList(&left, &right, docidLeft, pOut);
+      docidLeft = nextDocid(&left);
+      docidRight = nextDocid(&right);
+    }
+  }
+}
+
+/* We have two doclists:  pLeft and pRight.
+** Write the intersection of these two doclists into pOut.
+** Only docids are matched.  Position information is ignored.
+**
+** The output pOut never holds positions.
+*/
+static void docListAndMerge(
+  DocList *pLeft,    /* Doclist resulting from the words on the left */
+  DocList *pRight,   /* Doclist for the next word to the right */
+  DocList *pOut      /* Write the combined doclist here */
+){
+  DocListReader left, right;
+  sqlite_int64 docidLeft, docidRight;
+
+  assert( pOut->iType<DL_POSITIONS );
+
+  readerInit(&left, pLeft);
+  readerInit(&right, pRight);
+  docidLeft = nextDocid(&left);
+  docidRight = nextDocid(&right);
+
+  while( docidLeft>0 && docidRight>0 ){
+    if( docidLeft<docidRight ){
+      docidLeft = nextDocid(&left);
+    }else if( docidRight<docidLeft ){
+      docidRight = nextDocid(&right);
+    }else{
+      docListAddDocid(pOut, docidLeft);
+      docidLeft = nextDocid(&left);
+      docidRight = nextDocid(&right);
+    }
+  }
+}
+
+/* We have two doclists:  pLeft and pRight.
+** Write the union of these two doclists into pOut.
+** Only docids are matched.  Position information is ignored.
+**
+** The output pOut never holds positions.
+*/
+static void docListOrMerge(
+  DocList *pLeft,    /* Doclist resulting from the words on the left */
+  DocList *pRight,   /* Doclist for the next word to the right */
+  DocList *pOut      /* Write the combined doclist here */
+){
+  DocListReader left, right;
+  sqlite_int64 docidLeft, docidRight, priorLeft;
+
+  readerInit(&left, pLeft);
+  readerInit(&right, pRight);
+  docidLeft = nextDocid(&left);
+  docidRight = nextDocid(&right);
+
+  while( docidLeft>0 && docidRight>0 ){
+    if( docidLeft<=docidRight ){
+      docListAddDocid(pOut, docidLeft);
+    }else{
+      docListAddDocid(pOut, docidRight);
+    }
+    priorLeft = docidLeft;
+    if( docidLeft<=docidRight ){
+      docidLeft = nextDocid(&left);
+    }
+    if( docidRight>0 && docidRight<=priorLeft ){
+      docidRight = nextDocid(&right);
+    }
+  }
+  while( docidLeft>0 ){
+    docListAddDocid(pOut, docidLeft);
+    docidLeft = nextDocid(&left);
+  }
+  while( docidRight>0 ){
+    docListAddDocid(pOut, docidRight);
+    docidRight = nextDocid(&right);
+  }
+}
+
+/* We have two doclists:  pLeft and pRight.
+** Write into pOut all documents that occur in pLeft but not
+** in pRight.
+**
+** Only docids are matched.  Position information is ignored.
+**
+** The output pOut never holds positions.
+*/
+static void docListExceptMerge(
+  DocList *pLeft,    /* Doclist resulting from the words on the left */
+  DocList *pRight,   /* Doclist for the next word to the right */
+  DocList *pOut      /* Write the combined doclist here */
+){
+  DocListReader left, right;
+  sqlite_int64 docidLeft, docidRight, priorLeft;
+
+  readerInit(&left, pLeft);
+  readerInit(&right, pRight);
+  docidLeft = nextDocid(&left);
+  docidRight = nextDocid(&right);
+
+  while( docidLeft>0 && docidRight>0 ){
+    priorLeft = docidLeft;
+    if( docidLeft<docidRight ){
+      docListAddDocid(pOut, docidLeft);
+    }
+    if( docidLeft<=docidRight ){
+      docidLeft = nextDocid(&left);
+    }
+    if( docidRight>0 && docidRight<=priorLeft ){
+      docidRight = nextDocid(&right);
+    }
+  }
+  while( docidLeft>0 ){
+    docListAddDocid(pOut, docidLeft);
+    docidLeft = nextDocid(&left);
+  }
+}
+
+static char *string_dup_n(const char *s, int n){
+  char *str = malloc(n + 1);
+  memcpy(str, s, n);
+  str[n] = '\0';
+  return str;
+}
+
+/* Duplicate a string; the caller must free() the returned string.
+ * (We don't use strdup() since it's not part of the standard C library and
+ * may not be available everywhere.) */
+static char *string_dup(const char *s){
+  return string_dup_n(s, strlen(s));
+}
+
+/* Format a string, replacing each occurrence of the % character with
+ * zDb.zName.  This may be more convenient than sqlite_mprintf()
+ * when one string is used repeatedly in a format string.
+ * The caller must free() the returned string. */
+static char *string_format(const char *zFormat,
+                           const char *zDb, const char *zName){
+  const char *p;
+  size_t len = 0;
+  size_t nDb = strlen(zDb);
+  size_t nName = strlen(zName);
+  size_t nFullTableName = nDb+1+nName;
+  char *result;
+  char *r;
+
+  /* first compute length needed */
+  for(p = zFormat ; *p ; ++p){
+    len += (*p=='%' ? nFullTableName : 1);
+  }
+  len += 1;  /* for null terminator */
+
+  r = result = malloc(len);
+  for(p = zFormat; *p; ++p){
+    if( *p=='%' ){
+      memcpy(r, zDb, nDb);
+      r += nDb;
+      *r++ = '.';
+      memcpy(r, zName, nName);
+      r += nName;
+    } else {
+      *r++ = *p;
+    }
+  }
+  *r++ = '\0';
+  assert( r == result + len );
+  return result;
+}
+
+static int sql_exec(sqlite3 *db, const char *zDb, const char *zName,
+                    const char *zFormat){
+  char *zCommand = string_format(zFormat, zDb, zName);
+  int rc;
+  TRACE(("FTS1 sql: %s\n", zCommand));
+  rc = sqlite3_exec(db, zCommand, NULL, 0, NULL);
+  free(zCommand);
+  return rc;
+}
+
+static int sql_prepare(sqlite3 *db, const char *zDb, const char *zName,
+                       sqlite3_stmt **ppStmt, const char *zFormat){
+  char *zCommand = string_format(zFormat, zDb, zName);
+  int rc;
+  TRACE(("FTS1 prepare: %s\n", zCommand));
+  rc = sqlite3_prepare(db, zCommand, -1, ppStmt, NULL);
+  free(zCommand);
+  return rc;
+}
+
+/* end utility functions */
+
+/* Forward reference */
+typedef struct fulltext_vtab fulltext_vtab;
+
+/* A single term in a query is represented by an instances of
+** the following structure.
+*/
+typedef struct QueryTerm {
+  short int nPhrase; /* How many following terms are part of the same phrase */
+  short int iPhrase; /* This is the i-th term of a phrase. */
+  short int iColumn; /* Column of the index that must match this term */
+  signed char isOr;  /* this term is preceded by "OR" */
+  signed char isNot; /* this term is preceded by "-" */
+  char *pTerm;       /* text of the term.  '\000' terminated.  malloced */
+  int nTerm;         /* Number of bytes in pTerm[] */
+} QueryTerm;
+
+
+/* A query string is parsed into a Query structure.
+ *
+ * We could, in theory, allow query strings to be complicated
+ * nested expressions with precedence determined by parentheses.
+ * But none of the major search engines do this.  (Perhaps the
+ * feeling is that an parenthesized expression is two complex of
+ * an idea for the average user to grasp.)  Taking our lead from
+ * the major search engines, we will allow queries to be a list
+ * of terms (with an implied AND operator) or phrases in double-quotes,
+ * with a single optional "-" before each non-phrase term to designate
+ * negation and an optional OR connector.
+ *
+ * OR binds more tightly than the implied AND, which is what the
+ * major search engines seem to do.  So, for example:
+ * 
+ *    [one two OR three]     ==>    one AND (two OR three)
+ *    [one OR two three]     ==>    (one OR two) AND three
+ *
+ * A "-" before a term matches all entries that lack that term.
+ * The "-" must occur immediately before the term with in intervening
+ * space.  This is how the search engines do it.
+ *
+ * A NOT term cannot be the right-hand operand of an OR.  If this
+ * occurs in the query string, the NOT is ignored:
+ *
+ *    [one OR -two]          ==>    one OR two
+ *
+ */
+typedef struct Query {
+  fulltext_vtab *pFts;  /* The full text index */
+  int nTerms;           /* Number of terms in the query */
+  QueryTerm *pTerms;    /* Array of terms.  Space obtained from malloc() */
+  int nextIsOr;         /* Set the isOr flag on the next inserted term */
+  int nextColumn;       /* Next word parsed must be in this column */
+  int dfltColumn;       /* The default column */
+} Query;
+
+
+/*
+** An instance of the following structure keeps track of generated
+** matching-word offset information and snippets.
+*/
+typedef struct Snippet {
+  int nMatch;     /* Total number of matches */
+  int nAlloc;     /* Space allocated for aMatch[] */
+  struct snippetMatch { /* One entry for each matching term */
+    char snStatus;       /* Status flag for use while constructing snippets */
+    short int iCol;      /* The column that contains the match */
+    short int iTerm;     /* The index in Query.pTerms[] of the matching term */
+    short int nByte;     /* Number of bytes in the term */
+    int iStart;          /* The offset to the first character of the term */
+  } *aMatch;      /* Points to space obtained from malloc */
+  char *zOffset;  /* Text rendering of aMatch[] */
+  int nOffset;    /* strlen(zOffset) */
+  char *zSnippet; /* Snippet text */
+  int nSnippet;   /* strlen(zSnippet) */
+} Snippet;
+
+
+typedef enum QueryType {
+  QUERY_GENERIC,   /* table scan */
+  QUERY_ROWID,     /* lookup by rowid */
+  QUERY_FULLTEXT   /* QUERY_FULLTEXT + [i] is a full-text search for column i*/
+} QueryType;
+
+/* TODO(shess) CHUNK_MAX controls how much data we allow in segment 0
+** before we start aggregating into larger segments.  Lower CHUNK_MAX
+** means that for a given input we have more individual segments per
+** term, which means more rows in the table and a bigger index (due to
+** both more rows and bigger rowids).  But it also reduces the average
+** cost of adding new elements to the segment 0 doclist, and it seems
+** to reduce the number of pages read and written during inserts.  256
+** was chosen by measuring insertion times for a certain input (first
+** 10k documents of Enron corpus), though including query performance
+** in the decision may argue for a larger value.
+*/
+#define CHUNK_MAX 256
+
+typedef enum fulltext_statement {
+  CONTENT_INSERT_STMT,
+  CONTENT_SELECT_STMT,
+  CONTENT_UPDATE_STMT,
+  CONTENT_DELETE_STMT,
+
+  TERM_SELECT_STMT,
+  TERM_SELECT_ALL_STMT,
+  TERM_INSERT_STMT,
+  TERM_UPDATE_STMT,
+  TERM_DELETE_STMT,
+
+  MAX_STMT                     /* Always at end! */
+} fulltext_statement;
+
+/* These must exactly match the enum above. */
+/* TODO(adam): Is there some risk that a statement (in particular,
+** pTermSelectStmt) will be used in two cursors at once, e.g.  if a
+** query joins a virtual table to itself?  If so perhaps we should
+** move some of these to the cursor object.
+*/
+static const char *const fulltext_zStatement[MAX_STMT] = {
+  /* CONTENT_INSERT */ NULL,  /* generated in contentInsertStatement() */
+  /* CONTENT_SELECT */ "select * from %_content where rowid = ?",
+  /* CONTENT_UPDATE */ NULL,  /* generated in contentUpdateStatement() */
+  /* CONTENT_DELETE */ "delete from %_content where rowid = ?",
+
+  /* TERM_SELECT */
+  "select rowid, doclist from %_term where term = ? and segment = ?",
+  /* TERM_SELECT_ALL */
+  "select doclist from %_term where term = ? order by segment",
+  /* TERM_INSERT */
+  "insert into %_term (rowid, term, segment, doclist) values (?, ?, ?, ?)",
+  /* TERM_UPDATE */ "update %_term set doclist = ? where rowid = ?",
+  /* TERM_DELETE */ "delete from %_term where rowid = ?",
+};
+
+/*
+** A connection to a fulltext index is an instance of the following
+** structure.  The xCreate and xConnect methods create an instance
+** of this structure and xDestroy and xDisconnect free that instance.
+** All other methods receive a pointer to the structure as one of their
+** arguments.
+*/
+struct fulltext_vtab {
+  sqlite3_vtab base;               /* Base class used by SQLite core */
+  sqlite3 *db;                     /* The database connection */
+  const char *zDb;                 /* logical database name */
+  const char *zName;               /* virtual table name */
+  int nColumn;                     /* number of columns in virtual table */
+  char **azColumn;                 /* column names.  malloced */
+  char **azContentColumn;          /* column names in content table; malloced */
+  sqlite3_tokenizer *pTokenizer;   /* tokenizer for inserts and queries */
+
+  /* Precompiled statements which we keep as long as the table is
+  ** open.
+  */
+  sqlite3_stmt *pFulltextStatements[MAX_STMT];
+};
+
+/*
+** When the core wants to do a query, it create a cursor using a
+** call to xOpen.  This structure is an instance of a cursor.  It
+** is destroyed by xClose.
+*/
+typedef struct fulltext_cursor {
+  sqlite3_vtab_cursor base;        /* Base class used by SQLite core */
+  QueryType iCursorType;           /* Copy of sqlite3_index_info.idxNum */
+  sqlite3_stmt *pStmt;             /* Prepared statement in use by the cursor */
+  int eof;                         /* True if at End Of Results */
+  Query q;                         /* Parsed query string */
+  Snippet snippet;                 /* Cached snippet for the current row */
+  int iColumn;                     /* Column being searched */
+  DocListReader result;  /* used when iCursorType == QUERY_FULLTEXT */ 
+} fulltext_cursor;
+
+static struct fulltext_vtab *cursor_vtab(fulltext_cursor *c){
+  return (fulltext_vtab *) c->base.pVtab;
+}
+
+static const sqlite3_module fulltextModule;   /* forward declaration */
+
+/* Append a list of strings separated by commas to a StringBuffer. */
+static void appendList(StringBuffer *sb, int nString, char **azString){
+  int i;
+  for(i=0; i<nString; ++i){
+    if( i>0 ) append(sb, ", ");
+    append(sb, azString[i]);
+  }
+}
+
+/* Return a dynamically generated statement of the form
+ *   insert into %_content (rowid, ...) values (?, ...)
+ */
+static const char *contentInsertStatement(fulltext_vtab *v){
+  StringBuffer sb;
+  int i;
+
+  initStringBuffer(&sb);
+  append(&sb, "insert into %_content (rowid, ");
+  appendList(&sb, v->nColumn, v->azContentColumn);
+  append(&sb, ") values (?");
+  for(i=0; i<v->nColumn; ++i)
+    append(&sb, ", ?");
+  append(&sb, ")");
+  return sb.s;
+}
+
+/* Return a dynamically generated statement of the form
+ *   update %_content set [col_0] = ?, [col_1] = ?, ...
+ *                    where rowid = ?
+ */
+static const char *contentUpdateStatement(fulltext_vtab *v){
+  StringBuffer sb;
+  int i;
+
+  initStringBuffer(&sb);
+  append(&sb, "update %_content set ");
+  for(i=0; i<v->nColumn; ++i) {
+    if( i>0 ){
+      append(&sb, ", ");
+    }
+    append(&sb, v->azContentColumn[i]);
+    append(&sb, " = ?");
+  }
+  append(&sb, " where rowid = ?");
+  return sb.s;
+}
+
+/* Puts a freshly-prepared statement determined by iStmt in *ppStmt.
+** If the indicated statement has never been prepared, it is prepared
+** and cached, otherwise the cached version is reset.
+*/
+static int sql_get_statement(fulltext_vtab *v, fulltext_statement iStmt,
+                             sqlite3_stmt **ppStmt){
+  assert( iStmt<MAX_STMT );
+  if( v->pFulltextStatements[iStmt]==NULL ){
+    const char *zStmt;
+    int rc;
+    switch( iStmt ){
+      case CONTENT_INSERT_STMT:
+        zStmt = contentInsertStatement(v); break;
+      case CONTENT_UPDATE_STMT:
+        zStmt = contentUpdateStatement(v); break;
+      default:
+        zStmt = fulltext_zStatement[iStmt];
+    }
+    rc = sql_prepare(v->db, v->zDb, v->zName, &v->pFulltextStatements[iStmt],
+                         zStmt);
+    if( zStmt != fulltext_zStatement[iStmt]) free((void *) zStmt);
+    if( rc!=SQLITE_OK ) return rc;
+  } else {
+    int rc = sqlite3_reset(v->pFulltextStatements[iStmt]);
+    if( rc!=SQLITE_OK ) return rc;
+  }
+
+  *ppStmt = v->pFulltextStatements[iStmt];
+  return SQLITE_OK;
+}
+
+/* Step the indicated statement, handling errors SQLITE_BUSY (by
+** retrying) and SQLITE_SCHEMA (by re-preparing and transferring
+** bindings to the new statement).
+** TODO(adam): We should extend this function so that it can work with
+** statements declared locally, not only globally cached statements.
+*/
+static int sql_step_statement(fulltext_vtab *v, fulltext_statement iStmt,
+                              sqlite3_stmt **ppStmt){
+  int rc;
+  sqlite3_stmt *s = *ppStmt;
+  assert( iStmt<MAX_STMT );
+  assert( s==v->pFulltextStatements[iStmt] );
+
+  while( (rc=sqlite3_step(s))!=SQLITE_DONE && rc!=SQLITE_ROW ){
+    if( rc==SQLITE_BUSY ) continue;
+    if( rc!=SQLITE_ERROR ) return rc;
+
+    /* If an SQLITE_SCHEMA error has occured, then finalizing this
+     * statement is going to delete the fulltext_vtab structure. If
+     * the statement just executed is in the pFulltextStatements[]
+     * array, it will be finalized twice. So remove it before
+     * calling sqlite3_finalize().
+     */
+    v->pFulltextStatements[iStmt] = NULL;
+    rc = sqlite3_finalize(s);
+    break;
+  }
+  return rc;
+
+ err:
+  sqlite3_finalize(s);
+  return rc;
+}
+
+/* Like sql_step_statement(), but convert SQLITE_DONE to SQLITE_OK.
+** Useful for statements like UPDATE, where we expect no results.
+*/
+static int sql_single_step_statement(fulltext_vtab *v,
+                                     fulltext_statement iStmt,
+                                     sqlite3_stmt **ppStmt){
+  int rc = sql_step_statement(v, iStmt, ppStmt);
+  return (rc==SQLITE_DONE) ? SQLITE_OK : rc;
+}
+
+/* insert into %_content (rowid, ...) values ([rowid], [pValues]) */
+static int content_insert(fulltext_vtab *v, sqlite3_value *rowid,
+                          sqlite3_value **pValues){
+  sqlite3_stmt *s;
+  int i;
+  int rc = sql_get_statement(v, CONTENT_INSERT_STMT, &s);
+  if( rc!=SQLITE_OK ) return rc;
+
+  rc = sqlite3_bind_value(s, 1, rowid);
+  if( rc!=SQLITE_OK ) return rc;
+
+  for(i=0; i<v->nColumn; ++i){
+    rc = sqlite3_bind_value(s, 2+i, pValues[i]);
+    if( rc!=SQLITE_OK ) return rc;
+  }
+
+  return sql_single_step_statement(v, CONTENT_INSERT_STMT, &s);
+}
+
+/* update %_content set col0 = pValues[0], col1 = pValues[1], ...
+ *                  where rowid = [iRowid] */
+static int content_update(fulltext_vtab *v, sqlite3_value **pValues,
+                          sqlite_int64 iRowid){
+  sqlite3_stmt *s;
+  int i;
+  int rc = sql_get_statement(v, CONTENT_UPDATE_STMT, &s);
+  if( rc!=SQLITE_OK ) return rc;
+
+  for(i=0; i<v->nColumn; ++i){
+    rc = sqlite3_bind_value(s, 1+i, pValues[i]);
+    if( rc!=SQLITE_OK ) return rc;
+  }
+
+  rc = sqlite3_bind_int64(s, 1+v->nColumn, iRowid);
+  if( rc!=SQLITE_OK ) return rc;
+
+  return sql_single_step_statement(v, CONTENT_UPDATE_STMT, &s);
+}
+
+static void freeStringArray(int nString, const char **pString){
+  int i;
+
+  for (i=0 ; i < nString ; ++i) {
+    if( pString[i]!=NULL ) free((void *) pString[i]);
+  }
+  free((void *) pString);
+}
+
+/* select * from %_content where rowid = [iRow]
+ * The caller must delete the returned array and all strings in it.
+ * null fields will be NULL in the returned array.
+ *
+ * TODO: Perhaps we should return pointer/length strings here for consistency
+ * with other code which uses pointer/length. */
+static int content_select(fulltext_vtab *v, sqlite_int64 iRow,
+                          const char ***pValues){
+  sqlite3_stmt *s;
+  const char **values;
+  int i;
+  int rc;
+
+  *pValues = NULL;
+
+  rc = sql_get_statement(v, CONTENT_SELECT_STMT, &s);
+  if( rc!=SQLITE_OK ) return rc;
+
+  rc = sqlite3_bind_int64(s, 1, iRow);
+  if( rc!=SQLITE_OK ) return rc;
+
+  rc = sql_step_statement(v, CONTENT_SELECT_STMT, &s);
+  if( rc!=SQLITE_ROW ) return rc;
+
+  values = (const char **) malloc(v->nColumn * sizeof(const char *));
+  for(i=0; i<v->nColumn; ++i){
+    if( sqlite3_column_type(s, i)==SQLITE_NULL ){
+      values[i] = NULL;
+    }else{
+      values[i] = string_dup((char*)sqlite3_column_text(s, i));
+    }
+  }
+
+  /* We expect only one row.  We must execute another sqlite3_step()
+   * to complete the iteration; otherwise the table will remain locked. */
+  rc = sqlite3_step(s);
+  if( rc==SQLITE_DONE ){
+    *pValues = values;
+    return SQLITE_OK;
+  }
+
+  freeStringArray(v->nColumn, values);
+  return rc;
+}
+
+/* delete from %_content where rowid = [iRow ] */
+static int content_delete(fulltext_vtab *v, sqlite_int64 iRow){
+  sqlite3_stmt *s;
+  int rc = sql_get_statement(v, CONTENT_DELETE_STMT, &s);
+  if( rc!=SQLITE_OK ) return rc;
+
+  rc = sqlite3_bind_int64(s, 1, iRow);
+  if( rc!=SQLITE_OK ) return rc;
+
+  return sql_single_step_statement(v, CONTENT_DELETE_STMT, &s);
+}
+
+/* select rowid, doclist from %_term
+ *  where term = [pTerm] and segment = [iSegment]
+ * If found, returns SQLITE_ROW; the caller must free the
+ * returned doclist.  If no rows found, returns SQLITE_DONE. */
+static int term_select(fulltext_vtab *v, const char *pTerm, int nTerm,
+                       int iSegment,
+                       sqlite_int64 *rowid, DocList *out){
+  sqlite3_stmt *s;
+  int rc = sql_get_statement(v, TERM_SELECT_STMT, &s);
+  if( rc!=SQLITE_OK ) return rc;
+
+  rc = sqlite3_bind_text(s, 1, pTerm, nTerm, SQLITE_STATIC);
+  if( rc!=SQLITE_OK ) return rc;
+
+  rc = sqlite3_bind_int(s, 2, iSegment);
+  if( rc!=SQLITE_OK ) return rc;
+
+  rc = sql_step_statement(v, TERM_SELECT_STMT, &s);
+  if( rc!=SQLITE_ROW ) return rc;
+
+  *rowid = sqlite3_column_int64(s, 0);
+  docListInit(out, DL_DEFAULT,
+              sqlite3_column_blob(s, 1), sqlite3_column_bytes(s, 1));
+
+  /* We expect only one row.  We must execute another sqlite3_step()
+   * to complete the iteration; otherwise the table will remain locked. */
+  rc = sqlite3_step(s);
+  return rc==SQLITE_DONE ? SQLITE_ROW : rc;
+}
+
+/* Load the segment doclists for term pTerm and merge them in
+** appropriate order into out.  Returns SQLITE_OK if successful.  If
+** there are no segments for pTerm, successfully returns an empty
+** doclist in out.
+**
+** Each document consists of 1 or more "columns".  The number of
+** columns is v->nColumn.  If iColumn==v->nColumn, then return
+** position information about all columns.  If iColumn<v->nColumn,
+** then only return position information about the iColumn-th column
+** (where the first column is 0).
+*/
+static int term_select_all(
+  fulltext_vtab *v,     /* The fulltext index we are querying against */
+  int iColumn,          /* If <nColumn, only look at the iColumn-th column */
+  const char *pTerm,    /* The term whose posting lists we want */
+  int nTerm,            /* Number of bytes in pTerm */
+  DocList *out          /* Write the resulting doclist here */
+){
+  DocList doclist;
+  sqlite3_stmt *s;
+  int rc = sql_get_statement(v, TERM_SELECT_ALL_STMT, &s);
+  if( rc!=SQLITE_OK ) return rc;
+
+  rc = sqlite3_bind_text(s, 1, pTerm, nTerm, SQLITE_STATIC);
+  if( rc!=SQLITE_OK ) return rc;
+
+  docListInit(&doclist, DL_DEFAULT, 0, 0);
+
+  /* TODO(shess) Handle schema and busy errors. */
+  while( (rc=sql_step_statement(v, TERM_SELECT_ALL_STMT, &s))==SQLITE_ROW ){
+    DocList old;
+
+    /* TODO(shess) If we processed doclists from oldest to newest, we
+    ** could skip the malloc() involved with the following call.  For
+    ** now, I'd rather keep this logic similar to index_insert_term().
+    ** We could additionally drop elements when we see deletes, but
+    ** that would require a distinct version of docListAccumulate().
+    */
+    docListInit(&old, DL_DEFAULT,
+                sqlite3_column_blob(s, 0), sqlite3_column_bytes(s, 0));
+
+    if( iColumn<v->nColumn ){   /* querying a single column */
+      docListRestrictColumn(&old, iColumn);
+    }
+
+    /* doclist contains the newer data, so write it over old.  Then
+    ** steal accumulated result for doclist.
+    */
+    docListAccumulate(&old, &doclist);
+    docListDestroy(&doclist);
+    doclist = old;
+  }
+  if( rc!=SQLITE_DONE ){
+    docListDestroy(&doclist);
+    return rc;
+  }
+
+  docListDiscardEmpty(&doclist);
+  *out = doclist;
+  return SQLITE_OK;
+}
+
+/* insert into %_term (rowid, term, segment, doclist)
+               values ([piRowid], [pTerm], [iSegment], [doclist])
+** Lets sqlite select rowid if piRowid is NULL, else uses *piRowid.
+**
+** NOTE(shess) piRowid is IN, with values of "space of int64" plus
+** null, it is not used to pass data back to the caller.
+*/
+static int term_insert(fulltext_vtab *v, sqlite_int64 *piRowid,
+                       const char *pTerm, int nTerm,
+                       int iSegment, DocList *doclist){
+  sqlite3_stmt *s;
+  int rc = sql_get_statement(v, TERM_INSERT_STMT, &s);
+  if( rc!=SQLITE_OK ) return rc;
+
+  if( piRowid==NULL ){
+    rc = sqlite3_bind_null(s, 1);
+  }else{
+    rc = sqlite3_bind_int64(s, 1, *piRowid);
+  }
+  if( rc!=SQLITE_OK ) return rc;
+
+  rc = sqlite3_bind_text(s, 2, pTerm, nTerm, SQLITE_STATIC);
+  if( rc!=SQLITE_OK ) return rc;
+
+  rc = sqlite3_bind_int(s, 3, iSegment);
+  if( rc!=SQLITE_OK ) return rc;
+
+  rc = sqlite3_bind_blob(s, 4, doclist->pData, doclist->nData, SQLITE_STATIC);
+  if( rc!=SQLITE_OK ) return rc;
+
+  return sql_single_step_statement(v, TERM_INSERT_STMT, &s);
+}
+
+/* update %_term set doclist = [doclist] where rowid = [rowid] */
+static int term_update(fulltext_vtab *v, sqlite_int64 rowid,
+                       DocList *doclist){
+  sqlite3_stmt *s;
+  int rc = sql_get_statement(v, TERM_UPDATE_STMT, &s);
+  if( rc!=SQLITE_OK ) return rc;
+
+  rc = sqlite3_bind_blob(s, 1, doclist->pData, doclist->nData, SQLITE_STATIC);
+  if( rc!=SQLITE_OK ) return rc;
+
+  rc = sqlite3_bind_int64(s, 2, rowid);
+  if( rc!=SQLITE_OK ) return rc;
+
+  return sql_single_step_statement(v, TERM_UPDATE_STMT, &s);
+}
+
+static int term_delete(fulltext_vtab *v, sqlite_int64 rowid){
+  sqlite3_stmt *s;
+  int rc = sql_get_statement(v, TERM_DELETE_STMT, &s);
+  if( rc!=SQLITE_OK ) return rc;
+
+  rc = sqlite3_bind_int64(s, 1, rowid);
+  if( rc!=SQLITE_OK ) return rc;
+
+  return sql_single_step_statement(v, TERM_DELETE_STMT, &s);
+}
+
+/*
+** Free the memory used to contain a fulltext_vtab structure.
+*/
+static void fulltext_vtab_destroy(fulltext_vtab *v){
+  int iStmt, i;
+
+  TRACE(("FTS1 Destroy %p\n", v));
+  for( iStmt=0; iStmt<MAX_STMT; iStmt++ ){
+    if( v->pFulltextStatements[iStmt]!=NULL ){
+      sqlite3_finalize(v->pFulltextStatements[iStmt]);
+      v->pFulltextStatements[iStmt] = NULL;
+    }
+  }
+
+  if( v->pTokenizer!=NULL ){
+    v->pTokenizer->pModule->xDestroy(v->pTokenizer);
+    v->pTokenizer = NULL;
+  }
+  
+  free(v->azColumn);
+  for(i = 0; i < v->nColumn; ++i) {
+    sqlite3_free(v->azContentColumn[i]);
+  }
+  free(v->azContentColumn);
+  free(v);
+}
+
+/*
+** Token types for parsing the arguments to xConnect or xCreate.
+*/
+#define TOKEN_EOF         0    /* End of file */
+#define TOKEN_SPACE       1    /* Any kind of whitespace */
+#define TOKEN_ID          2    /* An identifier */
+#define TOKEN_STRING      3    /* A string literal */
+#define TOKEN_PUNCT       4    /* A single punctuation character */
+
+/*
+** If X is a character that can be used in an identifier then
+** IdChar(X) will be true.  Otherwise it is false.
+**
+** For ASCII, any character with the high-order bit set is
+** allowed in an identifier.  For 7-bit characters, 
+** sqlite3IsIdChar[X] must be 1.
+**
+** Ticket #1066.  the SQL standard does not allow '$' in the
+** middle of identfiers.  But many SQL implementations do. 
+** SQLite will allow '$' in identifiers for compatibility.
+** But the feature is undocumented.
+*/
+static const char isIdChar[] = {
+/* x0 x1 x2 x3 x4 x5 x6 x7 x8 x9 xA xB xC xD xE xF */
+    0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  /* 2x */
+    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0,  /* 3x */
+    0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  /* 4x */
+    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 1,  /* 5x */
+    0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  /* 6x */
+    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0,  /* 7x */
+};
+#define IdChar(C)  (((c=C)&0x80)!=0 || (c>0x1f && isIdChar[c-0x20]))
+
+
+/*
+** Return the length of the token that begins at z[0]. 
+** Store the token type in *tokenType before returning.
+*/
+static int getToken(const char *z, int *tokenType){
+  int i, c;
+  switch( *z ){
+    case 0: {
+      *tokenType = TOKEN_EOF;
+      return 0;
+    }
+    case ' ': case '\t': case '\n': case '\f': case '\r': {
+      for(i=1; safe_isspace(z[i]); i++){}
+      *tokenType = TOKEN_SPACE;
+      return i;
+    }
+    case '`':
+    case '\'':
+    case '"': {
+      int delim = z[0];
+      for(i=1; (c=z[i])!=0; i++){
+        if( c==delim ){
+          if( z[i+1]==delim ){
+            i++;
+          }else{
+            break;
+          }
+        }
+      }
+      *tokenType = TOKEN_STRING;
+      return i + (c!=0);
+    }
+    case '[': {
+      for(i=1, c=z[0]; c!=']' && (c=z[i])!=0; i++){}
+      *tokenType = TOKEN_ID;
+      return i;
+    }
+    default: {
+      if( !IdChar(*z) ){
+        break;
+      }
+      for(i=1; IdChar(z[i]); i++){}
+      *tokenType = TOKEN_ID;
+      return i;
+    }
+  }
+  *tokenType = TOKEN_PUNCT;
+  return 1;
+}
+
+/*
+** A token extracted from a string is an instance of the following
+** structure.
+*/
+typedef struct Token {
+  const char *z;       /* Pointer to token text.  Not '\000' terminated */
+  short int n;         /* Length of the token text in bytes. */
+} Token;
+
+/*
+** Given a input string (which is really one of the argv[] parameters
+** passed into xConnect or xCreate) split the string up into tokens.
+** Return an array of pointers to '\000' terminated strings, one string
+** for each non-whitespace token.
+**
+** The returned array is terminated by a single NULL pointer.
+**
+** Space to hold the returned array is obtained from a single
+** malloc and should be freed by passing the return value to free().
+** The individual strings within the token list are all a part of
+** the single memory allocation and will all be freed at once.
+*/
+static char **tokenizeString(const char *z, int *pnToken){
+  int nToken = 0;
+  Token *aToken = malloc( strlen(z) * sizeof(aToken[0]) );
+  int n = 1;
+  int e, i;
+  int totalSize = 0;
+  char **azToken;
+  char *zCopy;
+  while( n>0 ){
+    n = getToken(z, &e);
+    if( e!=TOKEN_SPACE ){
+      aToken[nToken].z = z;
+      aToken[nToken].n = n;
+      nToken++;
+      totalSize += n+1;
+    }
+    z += n;
+  }
+  azToken = (char**)malloc( nToken*sizeof(char*) + totalSize );
+  zCopy = (char*)&azToken[nToken];
+  nToken--;
+  for(i=0; i<nToken; i++){
+    azToken[i] = zCopy;
+    n = aToken[i].n;
+    memcpy(zCopy, aToken[i].z, n);
+    zCopy[n] = 0;
+    zCopy += n+1;
+  }
+  azToken[nToken] = 0;
+  free(aToken);
+  *pnToken = nToken;
+  return azToken;
+}
+
+/*
+** Convert an SQL-style quoted string into a normal string by removing
+** the quote characters.  The conversion is done in-place.  If the
+** input does not begin with a quote character, then this routine
+** is a no-op.
+**
+** Examples:
+**
+**     "abc"   becomes   abc
+**     'xyz'   becomes   xyz
+**     [pqr]   becomes   pqr
+**     `mno`   becomes   mno
+*/
+static void dequoteString(char *z){
+  int quote;
+  int i, j;
+  if( z==0 ) return;
+  quote = z[0];
+  switch( quote ){
+    case '\'':  break;
+    case '"':   break;
+    case '`':   break;                /* For MySQL compatibility */
+    case '[':   quote = ']';  break;  /* For MS SqlServer compatibility */
+    default:    return;
+  }
+  for(i=1, j=0; z[i]; i++){
+    if( z[i]==quote ){
+      if( z[i+1]==quote ){
+        z[j++] = quote;
+        i++;
+      }else{
+        z[j++] = 0;
+        break;
+      }
+    }else{
+      z[j++] = z[i];
+    }
+  }
+}
+
+/*
+** The input azIn is a NULL-terminated list of tokens.  Remove the first
+** token and all punctuation tokens.  Remove the quotes from
+** around string literal tokens.
+**
+** Example:
+**
+**     input:      tokenize chinese ( 'simplifed' , 'mixed' )
+**     output:     chinese simplifed mixed
+**
+** Another example:
+**
+**     input:      delimiters ( '[' , ']' , '...' )
+**     output:     [ ] ...
+*/
+static void tokenListToIdList(char **azIn){
+  int i, j;
+  if( azIn ){
+    for(i=0, j=-1; azIn[i]; i++){
+      if( safe_isalnum(azIn[i][0]) || azIn[i][1] ){
+        dequoteString(azIn[i]);
+        if( j>=0 ){
+          azIn[j] = azIn[i];
+        }
+        j++;
+      }
+    }
+    azIn[j] = 0;
+  }
+}
+
+
+/*
+** Find the first alphanumeric token in the string zIn.  Null-terminate
+** this token.  Remove any quotation marks.  And return a pointer to
+** the result.
+*/
+static char *firstToken(char *zIn, char **pzTail){
+  int n, ttype;
+  while(1){
+    n = getToken(zIn, &ttype);
+    if( ttype==TOKEN_SPACE ){
+      zIn += n;
+    }else if( ttype==TOKEN_EOF ){
+      *pzTail = zIn;
+      return 0;
+    }else{
+      zIn[n] = 0;
+      *pzTail = &zIn[1];
+      dequoteString(zIn);
+      return zIn;
+    }
+  }
+  /*NOTREACHED*/
+}
+
+/* Return true if...
+**
+**   *  s begins with the string t, ignoring case
+**   *  s is longer than t
+**   *  The first character of s beyond t is not a alphanumeric
+** 
+** Ignore leading space in *s.
+**
+** To put it another way, return true if the first token of
+** s[] is t[].
+*/
+static int startsWith(const char *s, const char *t){
+  while( safe_isspace(*s) ){ s++; }
+  while( *t ){
+    if( safe_tolower(*s++)!=safe_tolower(*t++) ) return 0;
+  }
+  return *s!='_' && !safe_isalnum(*s);
+}
+
+/*
+** An instance of this structure defines the "spec" of a
+** full text index.  This structure is populated by parseSpec
+** and use by fulltextConnect and fulltextCreate.
+*/
+typedef struct TableSpec {
+  const char *zDb;         /* Logical database name */
+  const char *zName;       /* Name of the full-text index */
+  int nColumn;             /* Number of columns to be indexed */
+  char **azColumn;         /* Original names of columns to be indexed */
+  char **azContentColumn;  /* Column names for %_content */
+  char **azTokenizer;      /* Name of tokenizer and its arguments */
+} TableSpec;
+
+/*
+** Reclaim all of the memory used by a TableSpec
+*/
+static void clearTableSpec(TableSpec *p) {
+  free(p->azColumn);
+  free(p->azContentColumn);
+  free(p->azTokenizer);
+}
+
+/* Parse a CREATE VIRTUAL TABLE statement, which looks like this:
+ *
+ * CREATE VIRTUAL TABLE email
+ *        USING fts1(subject, body, tokenize mytokenizer(myarg))
+ *
+ * We return parsed information in a TableSpec structure.
+ * 
+ */
+static int parseSpec(TableSpec *pSpec, int argc, const char *const*argv,
+                     char**pzErr){
+  int i, n;
+  char *z, *zDummy;
+  char **azArg;
+  const char *zTokenizer = 0;    /* argv[] entry describing the tokenizer */
+
+  assert( argc>=3 );
+  /* Current interface:
+  ** argv[0] - module name
+  ** argv[1] - database name
+  ** argv[2] - table name
+  ** argv[3..] - columns, optionally followed by tokenizer specification
+  **             and snippet delimiters specification.
+  */
+
+  /* Make a copy of the complete argv[][] array in a single allocation.
+  ** The argv[][] array is read-only and transient.  We can write to the
+  ** copy in order to modify things and the copy is persistent.
+  */
+  memset(pSpec, 0, sizeof(*pSpec));
+  for(i=n=0; i<argc; i++){
+    n += strlen(argv[i]) + 1;
+  }
+  azArg = malloc( sizeof(char*)*argc + n );
+  if( azArg==0 ){
+    return SQLITE_NOMEM;
+  }
+  z = (char*)&azArg[argc];
+  for(i=0; i<argc; i++){
+    azArg[i] = z;
+    strcpy(z, argv[i]);
+    z += strlen(z)+1;
+  }
+
+  /* Identify the column names and the tokenizer and delimiter arguments
+  ** in the argv[][] array.
+  */
+  pSpec->zDb = azArg[1];
+  pSpec->zName = azArg[2];
+  pSpec->nColumn = 0;
+  pSpec->azColumn = azArg;
+  zTokenizer = "tokenize simple";
+  for(i=3; i<argc; ++i){
+    if( startsWith(azArg[i],"tokenize") ){
+      zTokenizer = azArg[i];
+    }else{
+      z = azArg[pSpec->nColumn] = firstToken(azArg[i], &zDummy);
+      pSpec->nColumn++;
+    }
+  }
+  if( pSpec->nColumn==0 ){
+    azArg[0] = "content";
+    pSpec->nColumn = 1;
+  }
+
+  /*
+  ** Construct the list of content column names.
+  **
+  ** Each content column name will be of the form cNNAAAA
+  ** where NN is the column number and AAAA is the sanitized
+  ** column name.  "sanitized" means that special characters are
+  ** converted to "_".  The cNN prefix guarantees that all column
+  ** names are unique.
+  **
+  ** The AAAA suffix is not strictly necessary.  It is included
+  ** for the convenience of people who might examine the generated
+  ** %_content table and wonder what the columns are used for.
+  */
+  pSpec->azContentColumn = malloc( pSpec->nColumn * sizeof(char *) );
+  if( pSpec->azContentColumn==0 ){
+    clearTableSpec(pSpec);
+    return SQLITE_NOMEM;
+  }
+  for(i=0; i<pSpec->nColumn; i++){
+    char *p;
+    pSpec->azContentColumn[i] = sqlite3_mprintf("c%d%s", i, azArg[i]);
+    for (p = pSpec->azContentColumn[i]; *p ; ++p) {
+      if( !safe_isalnum(*p) ) *p = '_';
+    }
+  }
+
+  /*
+  ** Parse the tokenizer specification string.
+  */
+  pSpec->azTokenizer = tokenizeString(zTokenizer, &n);
+  tokenListToIdList(pSpec->azTokenizer);
+
+  return SQLITE_OK;
+}
+
+/*
+** Generate a CREATE TABLE statement that describes the schema of
+** the virtual table.  Return a pointer to this schema string.
+**
+** Space is obtained from sqlite3_mprintf() and should be freed
+** using sqlite3_free().
+*/
+static char *fulltextSchema(
+  int nColumn,                  /* Number of columns */
+  const char *const* azColumn,  /* List of columns */
+  const char *zTableName        /* Name of the table */
+){
+  int i;
+  char *zSchema, *zNext;
+  const char *zSep = "(";
+  zSchema = sqlite3_mprintf("CREATE TABLE x");
+  for(i=0; i<nColumn; i++){
+    zNext = sqlite3_mprintf("%s%s%Q", zSchema, zSep, azColumn[i]);
+    sqlite3_free(zSchema);
+    zSchema = zNext;
+    zSep = ",";
+  }
+  zNext = sqlite3_mprintf("%s,%Q)", zSchema, zTableName);
+  sqlite3_free(zSchema);
+  return zNext;
+}
+
+/*
+** Build a new sqlite3_vtab structure that will describe the
+** fulltext index defined by spec.
+*/
+static int constructVtab(
+  sqlite3 *db,              /* The SQLite database connection */
+  TableSpec *spec,          /* Parsed spec information from parseSpec() */
+  sqlite3_vtab **ppVTab,    /* Write the resulting vtab structure here */
+  char **pzErr              /* Write any error message here */
+){
+  int rc;
+  int n;
+  fulltext_vtab *v = 0;
+  const sqlite3_tokenizer_module *m = NULL;
+  char *schema;
+
+  v = (fulltext_vtab *) malloc(sizeof(fulltext_vtab));
+  if( v==0 ) return SQLITE_NOMEM;
+  memset(v, 0, sizeof(*v));
+  /* sqlite will initialize v->base */
+  v->db = db;
+  v->zDb = spec->zDb;       /* Freed when azColumn is freed */
+  v->zName = spec->zName;   /* Freed when azColumn is freed */
+  v->nColumn = spec->nColumn;
+  v->azContentColumn = spec->azContentColumn;
+  spec->azContentColumn = 0;
+  v->azColumn = spec->azColumn;
+  spec->azColumn = 0;
+
+  if( spec->azTokenizer==0 ){
+    return SQLITE_NOMEM;
+  }
+  /* TODO(shess) For now, add new tokenizers as else if clauses. */
+  if( spec->azTokenizer[0]==0 || startsWith(spec->azTokenizer[0], "simple") ){
+    sqlite3Fts1SimpleTokenizerModule(&m);
+  }else if( startsWith(spec->azTokenizer[0], "porter") ){
+    sqlite3Fts1PorterTokenizerModule(&m);
+  }else{
+    *pzErr = sqlite3_mprintf("unknown tokenizer: %s", spec->azTokenizer[0]);
+    rc = SQLITE_ERROR;
+    goto err;
+  }
+  for(n=0; spec->azTokenizer[n]; n++){}
+  if( n ){
+    rc = m->xCreate(n-1, (const char*const*)&spec->azTokenizer[1],
+                    &v->pTokenizer);
+  }else{
+    rc = m->xCreate(0, 0, &v->pTokenizer);
+  }
+  if( rc!=SQLITE_OK ) goto err;
+  v->pTokenizer->pModule = m;
+
+  /* TODO: verify the existence of backing tables foo_content, foo_term */
+
+  schema = fulltextSchema(v->nColumn, (const char*const*)v->azColumn,
+                          spec->zName);
+  rc = sqlite3_declare_vtab(db, schema);
+  sqlite3_free(schema);
+  if( rc!=SQLITE_OK ) goto err;
+
+  memset(v->pFulltextStatements, 0, sizeof(v->pFulltextStatements));
+
+  *ppVTab = &v->base;
+  TRACE(("FTS1 Connect %p\n", v));
+
+  return rc;
+
+err:
+  fulltext_vtab_destroy(v);
+  return rc;
+}
+
+static int fulltextConnect(
+  sqlite3 *db,
+  void *pAux,
+  int argc, const char *const*argv,
+  sqlite3_vtab **ppVTab,
+  char **pzErr
+){
+  TableSpec spec;
+  int rc = parseSpec(&spec, argc, argv, pzErr);
+  if( rc!=SQLITE_OK ) return rc;
+
+  rc = constructVtab(db, &spec, ppVTab, pzErr);
+  clearTableSpec(&spec);
+  return rc;
+}
+
+  /* The %_content table holds the text of each document, with
+  ** the rowid used as the docid.
+  **
+  ** The %_term table maps each term to a document list blob
+  ** containing elements sorted by ascending docid, each element
+  ** encoded as:
+  **
+  **   docid varint-encoded
+  **   token elements:
+  **     position+1 varint-encoded as delta from previous position
+  **     start offset varint-encoded as delta from previous start offset
+  **     end offset varint-encoded as delta from start offset
+  **
+  ** The sentinel position of 0 indicates the end of the token list.
+  **
+  ** Additionally, doclist blobs are chunked into multiple segments,
+  ** using segment to order the segments.  New elements are added to
+  ** the segment at segment 0, until it exceeds CHUNK_MAX.  Then
+  ** segment 0 is deleted, and the doclist is inserted at segment 1.
+  ** If there is already a doclist at segment 1, the segment 0 doclist
+  ** is merged with it, the segment 1 doclist is deleted, and the
+  ** merged doclist is inserted at segment 2, repeating those
+  ** operations until an insert succeeds.
+  **
+  ** Since this structure doesn't allow us to update elements in place
+  ** in case of deletion or update, these are simply written to
+  ** segment 0 (with an empty token list in case of deletion), with
+  ** docListAccumulate() taking care to retain lower-segment
+  ** information in preference to higher-segment information.
+  */
+  /* TODO(shess) Provide a VACUUM type operation which both removes
+  ** deleted elements which are no longer necessary, and duplicated
+  ** elements.  I suspect this will probably not be necessary in
+  ** practice, though.
+  */
+static int fulltextCreate(sqlite3 *db, void *pAux,
+                          int argc, const char * const *argv,
+                          sqlite3_vtab **ppVTab, char **pzErr){
+  int rc;
+  TableSpec spec;
+  StringBuffer schema;
+  TRACE(("FTS1 Create\n"));
+
+  rc = parseSpec(&spec, argc, argv, pzErr);
+  if( rc!=SQLITE_OK ) return rc;
+
+  initStringBuffer(&schema);
+  append(&schema, "CREATE TABLE %_content(");
+  appendList(&schema, spec.nColumn, spec.azContentColumn);
+  append(&schema, ")");
+  rc = sql_exec(db, spec.zDb, spec.zName, schema.s);
+  free(schema.s);
+  if( rc!=SQLITE_OK ) goto out;
+
+  rc = sql_exec(db, spec.zDb, spec.zName,
+    "create table %_term(term text, segment integer, doclist blob, "
+                        "primary key(term, segment));");
+  if( rc!=SQLITE_OK ) goto out;
+
+  rc = constructVtab(db, &spec, ppVTab, pzErr);
+
+out:
+  clearTableSpec(&spec);
+  return rc;
+}
+
+/* Decide how to handle an SQL query. */
+static int fulltextBestIndex(sqlite3_vtab *pVTab, sqlite3_index_info *pInfo){
+  int i;
+  TRACE(("FTS1 BestIndex\n"));
+
+  for(i=0; i<pInfo->nConstraint; ++i){
+    const struct sqlite3_index_constraint *pConstraint;
+    pConstraint = &pInfo->aConstraint[i];
+    if( pConstraint->usable ) {
+      if( pConstraint->iColumn==-1 &&
+          pConstraint->op==SQLITE_INDEX_CONSTRAINT_EQ ){
+        pInfo->idxNum = QUERY_ROWID;      /* lookup by rowid */
+        TRACE(("FTS1 QUERY_ROWID\n"));
+      } else if( pConstraint->iColumn>=0 &&
+                 pConstraint->op==SQLITE_INDEX_CONSTRAINT_MATCH ){
+        /* full-text search */
+        pInfo->idxNum = QUERY_FULLTEXT + pConstraint->iColumn;
+        TRACE(("FTS1 QUERY_FULLTEXT %d\n", pConstraint->iColumn));
+      } else continue;
+
+      pInfo->aConstraintUsage[i].argvIndex = 1;
+      pInfo->aConstraintUsage[i].omit = 1;
+
+      /* An arbitrary value for now.
+       * TODO: Perhaps rowid matches should be considered cheaper than
+       * full-text searches. */
+      pInfo->estimatedCost = 1.0;   
+
+      return SQLITE_OK;
+    }
+  }
+  pInfo->idxNum = QUERY_GENERIC;
+  return SQLITE_OK;
+}
+
+static int fulltextDisconnect(sqlite3_vtab *pVTab){
+  TRACE(("FTS1 Disconnect %p\n", pVTab));
+  fulltext_vtab_destroy((fulltext_vtab *)pVTab);
+  return SQLITE_OK;
+}
+
+static int fulltextDestroy(sqlite3_vtab *pVTab){
+  fulltext_vtab *v = (fulltext_vtab *)pVTab;
+  int rc;
+
+  TRACE(("FTS1 Destroy %p\n", pVTab));
+  rc = sql_exec(v->db, v->zDb, v->zName,
+                "drop table if exists %_content;"
+                "drop table if exists %_term;"
+                );
+  if( rc!=SQLITE_OK ) return rc;
+
+  fulltext_vtab_destroy((fulltext_vtab *)pVTab);
+  return SQLITE_OK;
+}
+
+static int fulltextOpen(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor){
+  fulltext_cursor *c;
+
+  c = (fulltext_cursor *) calloc(sizeof(fulltext_cursor), 1);
+  /* sqlite will initialize c->base */
+  *ppCursor = &c->base;
+  TRACE(("FTS1 Open %p: %p\n", pVTab, c));
+
+  return SQLITE_OK;
+}
+
+
+/* Free all of the dynamically allocated memory held by *q
+*/
+static void queryClear(Query *q){
+  int i;
+  for(i = 0; i < q->nTerms; ++i){
+    free(q->pTerms[i].pTerm);
+  }
+  free(q->pTerms);
+  memset(q, 0, sizeof(*q));
+}
+
+/* Free all of the dynamically allocated memory held by the
+** Snippet
+*/
+static void snippetClear(Snippet *p){
+  free(p->aMatch);
+  free(p->zOffset);
+  free(p->zSnippet);
+  memset(p, 0, sizeof(*p));
+}
+/*
+** Append a single entry to the p->aMatch[] log.
+*/
+static void snippetAppendMatch(
+  Snippet *p,               /* Append the entry to this snippet */
+  int iCol, int iTerm,      /* The column and query term */
+  int iStart, int nByte     /* Offset and size of the match */
+){
+  int i;
+  struct snippetMatch *pMatch;
+  if( p->nMatch+1>=p->nAlloc ){
+    p->nAlloc = p->nAlloc*2 + 10;
+    p->aMatch = realloc(p->aMatch, p->nAlloc*sizeof(p->aMatch[0]) );
+    if( p->aMatch==0 ){
+      p->nMatch = 0;
+      p->nAlloc = 0;
+      return;
+    }
+  }
+  i = p->nMatch++;
+  pMatch = &p->aMatch[i];
+  pMatch->iCol = iCol;
+  pMatch->iTerm = iTerm;
+  pMatch->iStart = iStart;
+  pMatch->nByte = nByte;
+}
+
+/*
+** Sizing information for the circular buffer used in snippetOffsetsOfColumn()
+*/
+#define FTS1_ROTOR_SZ   (32)
+#define FTS1_ROTOR_MASK (FTS1_ROTOR_SZ-1)
+
+/*
+** Add entries to pSnippet->aMatch[] for every match that occurs against
+** document zDoc[0..nDoc-1] which is stored in column iColumn.
+*/
+static void snippetOffsetsOfColumn(
+  Query *pQuery,
+  Snippet *pSnippet,
+  int iColumn,
+  const char *zDoc,
+  int nDoc
+){
+  const sqlite3_tokenizer_module *pTModule;  /* The tokenizer module */
+  sqlite3_tokenizer *pTokenizer;             /* The specific tokenizer */
+  sqlite3_tokenizer_cursor *pTCursor;        /* Tokenizer cursor */
+  fulltext_vtab *pVtab;                /* The full text index */
+  int nColumn;                         /* Number of columns in the index */
+  const QueryTerm *aTerm;              /* Query string terms */
+  int nTerm;                           /* Number of query string terms */  
+  int i, j;                            /* Loop counters */
+  int rc;                              /* Return code */
+  unsigned int match, prevMatch;       /* Phrase search bitmasks */
+  const char *zToken;                  /* Next token from the tokenizer */
+  int nToken;                          /* Size of zToken */
+  int iBegin, iEnd, iPos;              /* Offsets of beginning and end */
+
+  /* The following variables keep a circular buffer of the last
+  ** few tokens */
+  unsigned int iRotor = 0;             /* Index of current token */
+  int iRotorBegin[FTS1_ROTOR_SZ];      /* Beginning offset of token */
+  int iRotorLen[FTS1_ROTOR_SZ];        /* Length of token */
+
+  pVtab = pQuery->pFts;
+  nColumn = pVtab->nColumn;
+  pTokenizer = pVtab->pTokenizer;
+  pTModule = pTokenizer->pModule;
+  rc = pTModule->xOpen(pTokenizer, zDoc, nDoc, &pTCursor);
+  if( rc ) return;
+  pTCursor->pTokenizer = pTokenizer;
+  aTerm = pQuery->pTerms;
+  nTerm = pQuery->nTerms;
+  if( nTerm>=FTS1_ROTOR_SZ ){
+    nTerm = FTS1_ROTOR_SZ - 1;
+  }
+  prevMatch = 0;
+  while(1){
+    rc = pTModule->xNext(pTCursor, &zToken, &nToken, &iBegin, &iEnd, &iPos);
+    if( rc ) break;
+    iRotorBegin[iRotor&FTS1_ROTOR_MASK] = iBegin;
+    iRotorLen[iRotor&FTS1_ROTOR_MASK] = iEnd-iBegin;
+    match = 0;
+    for(i=0; i<nTerm; i++){
+      int iCol;
+      iCol = aTerm[i].iColumn;
+      if( iCol>=0 && iCol<nColumn && iCol!=iColumn ) continue;
+      if( aTerm[i].nTerm!=nToken ) continue;
+      if( memcmp(aTerm[i].pTerm, zToken, nToken) ) continue;
+      if( aTerm[i].iPhrase>1 && (prevMatch & (1<<i))==0 ) continue;
+      match |= 1<<i;
+      if( i==nTerm-1 || aTerm[i+1].iPhrase==1 ){
+        for(j=aTerm[i].iPhrase-1; j>=0; j--){
+          int k = (iRotor-j) & FTS1_ROTOR_MASK;
+          snippetAppendMatch(pSnippet, iColumn, i-j,
+                iRotorBegin[k], iRotorLen[k]);
+        }
+      }
+    }
+    prevMatch = match<<1;
+    iRotor++;
+  }
+  pTModule->xClose(pTCursor);  
+}
+
+
+/*
+** Compute all offsets for the current row of the query.  
+** If the offsets have already been computed, this routine is a no-op.
+*/
+static void snippetAllOffsets(fulltext_cursor *p){
+  int nColumn;
+  int iColumn, i;
+  int iFirst, iLast;
+  fulltext_vtab *pFts;
+
+  if( p->snippet.nMatch ) return;
+  if( p->q.nTerms==0 ) return;
+  pFts = p->q.pFts;
+  nColumn = pFts->nColumn;
+  iColumn = p->iCursorType - QUERY_FULLTEXT;
+  if( iColumn<0 || iColumn>=nColumn ){
+    iFirst = 0;
+    iLast = nColumn-1;
+  }else{
+    iFirst = iColumn;
+    iLast = iColumn;
+  }
+  for(i=iFirst; i<=iLast; i++){
+    const char *zDoc;
+    int nDoc;
+    zDoc = (const char*)sqlite3_column_text(p->pStmt, i+1);
+    nDoc = sqlite3_column_bytes(p->pStmt, i+1);
+    snippetOffsetsOfColumn(&p->q, &p->snippet, i, zDoc, nDoc);
+  }
+}
+
+/*
+** Convert the information in the aMatch[] array of the snippet
+** into the string zOffset[0..nOffset-1].
+*/
+static void snippetOffsetText(Snippet *p){
+  int i;
+  int cnt = 0;
+  StringBuffer sb;
+  char zBuf[200];
+  if( p->zOffset ) return;
+  initStringBuffer(&sb);
+  for(i=0; i<p->nMatch; i++){
+    struct snippetMatch *pMatch = &p->aMatch[i];
+    zBuf[0] = ' ';
+    sprintf(&zBuf[cnt>0], "%d %d %d %d", pMatch->iCol,
+        pMatch->iTerm, pMatch->iStart, pMatch->nByte);
+    append(&sb, zBuf);
+    cnt++;
+  }
+  p->zOffset = sb.s;
+  p->nOffset = sb.len;
+}
+
+/*
+** zDoc[0..nDoc-1] is phrase of text.  aMatch[0..nMatch-1] are a set
+** of matching words some of which might be in zDoc.  zDoc is column
+** number iCol.
+**
+** iBreak is suggested spot in zDoc where we could begin or end an
+** excerpt.  Return a value similar to iBreak but possibly adjusted
+** to be a little left or right so that the break point is better.
+*/
+static int wordBoundary(
+  int iBreak,                   /* The suggested break point */
+  const char *zDoc,             /* Document text */
+  int nDoc,                     /* Number of bytes in zDoc[] */
+  struct snippetMatch *aMatch,  /* Matching words */
+  int nMatch,                   /* Number of entries in aMatch[] */
+  int iCol                      /* The column number for zDoc[] */
+){
+  int i;
+  if( iBreak<=10 ){
+    return 0;
+  }
+  if( iBreak>=nDoc-10 ){
+    return nDoc;
+  }
+  for(i=0; i<nMatch && aMatch[i].iCol<iCol; i++){}
+  while( i<nMatch && aMatch[i].iStart+aMatch[i].nByte<iBreak ){ i++; }
+  if( i<nMatch ){
+    if( aMatch[i].iStart<iBreak+10 ){
+      return aMatch[i].iStart;
+    }
+    if( i>0 && aMatch[i-1].iStart+aMatch[i-1].nByte>=iBreak ){
+      return aMatch[i-1].iStart;
+    }
+  }
+  for(i=1; i<=10; i++){
+    if( safe_isspace(zDoc[iBreak-i]) ){
+      return iBreak - i + 1;
+    }
+    if( safe_isspace(zDoc[iBreak+i]) ){
+      return iBreak + i + 1;
+    }
+  }
+  return iBreak;
+}
+
+/*
+** If the StringBuffer does not end in white space, add a single
+** space character to the end.
+*/
+static void appendWhiteSpace(StringBuffer *p){
+  if( p->len==0 ) return;
+  if( safe_isspace(p->s[p->len-1]) ) return;
+  append(p, " ");
+}
+
+/*
+** Remove white space from teh end of the StringBuffer
+*/
+static void trimWhiteSpace(StringBuffer *p){
+  while( p->len>0 && safe_isspace(p->s[p->len-1]) ){
+    p->len--;
+  }
+}
+
+
+
+/*
+** Allowed values for Snippet.aMatch[].snStatus
+*/
+#define SNIPPET_IGNORE  0   /* It is ok to omit this match from the snippet */
+#define SNIPPET_DESIRED 1   /* We want to include this match in the snippet */
+
+/*
+** Generate the text of a snippet.
+*/
+static void snippetText(
+  fulltext_cursor *pCursor,   /* The cursor we need the snippet for */
+  const char *zStartMark,     /* Markup to appear before each match */
+  const char *zEndMark,       /* Markup to appear after each match */
+  const char *zEllipsis       /* Ellipsis mark */
+){
+  int i, j;
+  struct snippetMatch *aMatch;
+  int nMatch;
+  int nDesired;
+  StringBuffer sb;
+  int tailCol;
+  int tailOffset;
+  int iCol;
+  int nDoc;
+  const char *zDoc;
+  int iStart, iEnd;
+  int tailEllipsis = 0;
+  int iMatch;
+  
+
+  free(pCursor->snippet.zSnippet);
+  pCursor->snippet.zSnippet = 0;
+  aMatch = pCursor->snippet.aMatch;
+  nMatch = pCursor->snippet.nMatch;
+  initStringBuffer(&sb);
+
+  for(i=0; i<nMatch; i++){
+    aMatch[i].snStatus = SNIPPET_IGNORE;
+  }
+  nDesired = 0;
+  for(i=0; i<pCursor->q.nTerms; i++){
+    for(j=0; j<nMatch; j++){
+      if( aMatch[j].iTerm==i ){
+        aMatch[j].snStatus = SNIPPET_DESIRED;
+        nDesired++;
+        break;
+      }
+    }
+  }
+
+  iMatch = 0;
+  tailCol = -1;
+  tailOffset = 0;
+  for(i=0; i<nMatch && nDesired>0; i++){
+    if( aMatch[i].snStatus!=SNIPPET_DESIRED ) continue;
+    nDesired--;
+    iCol = aMatch[i].iCol;
+    zDoc = (const char*)sqlite3_column_text(pCursor->pStmt, iCol+1);
+    nDoc = sqlite3_column_bytes(pCursor->pStmt, iCol+1);
+    iStart = aMatch[i].iStart - 40;
+    iStart = wordBoundary(iStart, zDoc, nDoc, aMatch, nMatch, iCol);
+    if( iStart<=10 ){
+      iStart = 0;
+    }
+    if( iCol==tailCol && iStart<=tailOffset+20 ){
+      iStart = tailOffset;
+    }
+    if( (iCol!=tailCol && tailCol>=0) || iStart!=tailOffset ){
+      trimWhiteSpace(&sb);
+      appendWhiteSpace(&sb);
+      append(&sb, zEllipsis);
+      appendWhiteSpace(&sb);
+    }
+    iEnd = aMatch[i].iStart + aMatch[i].nByte + 40;
+    iEnd = wordBoundary(iEnd, zDoc, nDoc, aMatch, nMatch, iCol);
+    if( iEnd>=nDoc-10 ){
+      iEnd = nDoc;
+      tailEllipsis = 0;
+    }else{
+      tailEllipsis = 1;
+    }
+    while( iMatch<nMatch && aMatch[iMatch].iCol<iCol ){ iMatch++; }
+    while( iStart<iEnd ){
+      while( iMatch<nMatch && aMatch[iMatch].iStart<iStart
+             && aMatch[iMatch].iCol<=iCol ){
+        iMatch++;
+      }
+      if( iMatch<nMatch && aMatch[iMatch].iStart<iEnd
+             && aMatch[iMatch].iCol==iCol ){
+        nappend(&sb, &zDoc[iStart], aMatch[iMatch].iStart - iStart);
+        iStart = aMatch[iMatch].iStart;
+        append(&sb, zStartMark);
+        nappend(&sb, &zDoc[iStart], aMatch[iMatch].nByte);
+        append(&sb, zEndMark);
+        iStart += aMatch[iMatch].nByte;
+        for(j=iMatch+1; j<nMatch; j++){
+          if( aMatch[j].iTerm==aMatch[iMatch].iTerm
+              && aMatch[j].snStatus==SNIPPET_DESIRED ){
+            nDesired--;
+            aMatch[j].snStatus = SNIPPET_IGNORE;
+          }
+        }
+      }else{
+        nappend(&sb, &zDoc[iStart], iEnd - iStart);
+        iStart = iEnd;
+      }
+    }
+    tailCol = iCol;
+    tailOffset = iEnd;
+  }
+  trimWhiteSpace(&sb);
+  if( tailEllipsis ){
+    appendWhiteSpace(&sb);
+    append(&sb, zEllipsis);
+  }
+  pCursor->snippet.zSnippet = sb.s;
+  pCursor->snippet.nSnippet = sb.len;  
+}
+
+
+/*
+** Close the cursor.  For additional information see the documentation
+** on the xClose method of the virtual table interface.
+*/
+static int fulltextClose(sqlite3_vtab_cursor *pCursor){
+  fulltext_cursor *c = (fulltext_cursor *) pCursor;
+  TRACE(("FTS1 Close %p\n", c));
+  sqlite3_finalize(c->pStmt);
+  queryClear(&c->q);
+  snippetClear(&c->snippet);
+  if( c->result.pDoclist!=NULL ){
+    docListDelete(c->result.pDoclist);
+  }
+  free(c);
+  return SQLITE_OK;
+}
+
+static int fulltextNext(sqlite3_vtab_cursor *pCursor){
+  fulltext_cursor *c = (fulltext_cursor *) pCursor;
+  sqlite_int64 iDocid;
+  int rc;
+
+  TRACE(("FTS1 Next %p\n", pCursor));
+  snippetClear(&c->snippet);
+  if( c->iCursorType < QUERY_FULLTEXT ){
+    /* TODO(shess) Handle SQLITE_SCHEMA AND SQLITE_BUSY. */
+    rc = sqlite3_step(c->pStmt);
+    switch( rc ){
+      case SQLITE_ROW:
+        c->eof = 0;
+        return SQLITE_OK;
+      case SQLITE_DONE:
+        c->eof = 1;
+        return SQLITE_OK;
+      default:
+        c->eof = 1;
+        return rc;
+    }
+  } else {  /* full-text query */
+    rc = sqlite3_reset(c->pStmt);
+    if( rc!=SQLITE_OK ) return rc;
+
+    iDocid = nextDocid(&c->result);
+    if( iDocid==0 ){
+      c->eof = 1;
+      return SQLITE_OK;
+    }
+    rc = sqlite3_bind_int64(c->pStmt, 1, iDocid);
+    if( rc!=SQLITE_OK ) return rc;
+    /* TODO(shess) Handle SQLITE_SCHEMA AND SQLITE_BUSY. */
+    rc = sqlite3_step(c->pStmt);
+    if( rc==SQLITE_ROW ){   /* the case we expect */
+      c->eof = 0;
+      return SQLITE_OK;
+    }
+    /* an error occurred; abort */
+    return rc==SQLITE_DONE ? SQLITE_ERROR : rc;
+  }
+}
+
+
+/* Return a DocList corresponding to the query term *pTerm.  If *pTerm
+** is the first term of a phrase query, go ahead and evaluate the phrase
+** query and return the doclist for the entire phrase query.
+**
+** The result is stored in pTerm->doclist.
+*/
+static int docListOfTerm(
+  fulltext_vtab *v,     /* The full text index */
+  int iColumn,          /* column to restrict to.  No restrition if >=nColumn */
+  QueryTerm *pQTerm,    /* Term we are looking for, or 1st term of a phrase */
+  DocList **ppResult    /* Write the result here */
+){
+  DocList *pLeft, *pRight, *pNew;
+  int i, rc;
+
+  pLeft = docListNew(DL_POSITIONS);
+  rc = term_select_all(v, iColumn, pQTerm->pTerm, pQTerm->nTerm, pLeft);
+  if( rc ){
+    docListDelete(pLeft);
+    return rc;
+  }
+  for(i=1; i<=pQTerm->nPhrase; i++){
+    pRight = docListNew(DL_POSITIONS);
+    rc = term_select_all(v, iColumn, pQTerm[i].pTerm, pQTerm[i].nTerm, pRight);
+    if( rc ){
+      docListDelete(pLeft);
+      return rc;
+    }
+    pNew = docListNew(i<pQTerm->nPhrase ? DL_POSITIONS : DL_DOCIDS);
+    docListPhraseMerge(pLeft, pRight, pNew);
+    docListDelete(pLeft);
+    docListDelete(pRight);
+    pLeft = pNew;
+  }
+  *ppResult = pLeft;
+  return SQLITE_OK;
+}
+
+/* Add a new term pTerm[0..nTerm-1] to the query *q.
+*/
+static void queryAdd(Query *q, const char *pTerm, int nTerm){
+  QueryTerm *t;
+  ++q->nTerms;
+  q->pTerms = realloc(q->pTerms, q->nTerms * sizeof(q->pTerms[0]));
+  if( q->pTerms==0 ){
+    q->nTerms = 0;
+    return;
+  }
+  t = &q->pTerms[q->nTerms - 1];
+  memset(t, 0, sizeof(*t));
+  t->pTerm = malloc(nTerm+1);
+  memcpy(t->pTerm, pTerm, nTerm);
+  t->pTerm[nTerm] = 0;
+  t->nTerm = nTerm;
+  t->isOr = q->nextIsOr;
+  q->nextIsOr = 0;
+  t->iColumn = q->nextColumn;
+  q->nextColumn = q->dfltColumn;
+}
+
+/*
+** Check to see if the string zToken[0...nToken-1] matches any
+** column name in the virtual table.   If it does,
+** return the zero-indexed column number.  If not, return -1.
+*/
+static int checkColumnSpecifier(
+  fulltext_vtab *pVtab,    /* The virtual table */
+  const char *zToken,      /* Text of the token */
+  int nToken               /* Number of characters in the token */
+){
+  int i;
+  for(i=0; i<pVtab->nColumn; i++){
+    if( memcmp(pVtab->azColumn[i], zToken, nToken)==0
+        && pVtab->azColumn[i][nToken]==0 ){
+      return i;
+    }
+  }
+  return -1;
+}
+
+/*
+** Parse the text at pSegment[0..nSegment-1].  Add additional terms
+** to the query being assemblied in pQuery.
+**
+** inPhrase is true if pSegment[0..nSegement-1] is contained within
+** double-quotes.  If inPhrase is true, then the first term
+** is marked with the number of terms in the phrase less one and
+** OR and "-" syntax is ignored.  If inPhrase is false, then every
+** term found is marked with nPhrase=0 and OR and "-" syntax is significant.
+*/
+static int tokenizeSegment(
+  sqlite3_tokenizer *pTokenizer,          /* The tokenizer to use */
+  const char *pSegment, int nSegment,     /* Query expression being parsed */
+  int inPhrase,                           /* True if within "..." */
+  Query *pQuery                           /* Append results here */
+){
+  const sqlite3_tokenizer_module *pModule = pTokenizer->pModule;
+  sqlite3_tokenizer_cursor *pCursor;
+  int firstIndex = pQuery->nTerms;
+  int iCol;
+  int nTerm = 1;
+  
+  int rc = pModule->xOpen(pTokenizer, pSegment, nSegment, &pCursor);
+  if( rc!=SQLITE_OK ) return rc;
+  pCursor->pTokenizer = pTokenizer;
+
+  while( 1 ){
+    const char *pToken;
+    int nToken, iBegin, iEnd, iPos;
+
+    rc = pModule->xNext(pCursor,
+                        &pToken, &nToken,
+                        &iBegin, &iEnd, &iPos);
+    if( rc!=SQLITE_OK ) break;
+    if( !inPhrase &&
+        pSegment[iEnd]==':' &&
+         (iCol = checkColumnSpecifier(pQuery->pFts, pToken, nToken))>=0 ){
+      pQuery->nextColumn = iCol;
+      continue;
+    }
+    if( !inPhrase && pQuery->nTerms>0 && nToken==2
+         && pSegment[iBegin]=='O' && pSegment[iBegin+1]=='R' ){
+      pQuery->nextIsOr = 1;
+      continue;
+    }
+    queryAdd(pQuery, pToken, nToken);
+    if( !inPhrase && iBegin>0 && pSegment[iBegin-1]=='-' ){
+      pQuery->pTerms[pQuery->nTerms-1].isNot = 1;
+    }
+    pQuery->pTerms[pQuery->nTerms-1].iPhrase = nTerm;
+    if( inPhrase ){
+      nTerm++;
+    }
+  }
+
+  if( inPhrase && pQuery->nTerms>firstIndex ){
+    pQuery->pTerms[firstIndex].nPhrase = pQuery->nTerms - firstIndex - 1;
+  }
+
+  return pModule->xClose(pCursor);
+}
+
+/* Parse a query string, yielding a Query object pQuery.
+**
+** The calling function will need to queryClear() to clean up
+** the dynamically allocated memory held by pQuery.
+*/
+static int parseQuery(
+  fulltext_vtab *v,        /* The fulltext index */
+  const char *zInput,      /* Input text of the query string */
+  int nInput,              /* Size of the input text */
+  int dfltColumn,          /* Default column of the index to match against */
+  Query *pQuery            /* Write the parse results here. */
+){
+  int iInput, inPhrase = 0;
+
+  if( zInput==0 ) nInput = 0;
+  if( nInput<0 ) nInput = strlen(zInput);
+  pQuery->nTerms = 0;
+  pQuery->pTerms = NULL;
+  pQuery->nextIsOr = 0;
+  pQuery->nextColumn = dfltColumn;
+  pQuery->dfltColumn = dfltColumn;
+  pQuery->pFts = v;
+
+  for(iInput=0; iInput<nInput; ++iInput){
+    int i;
+    for(i=iInput; i<nInput && zInput[i]!='"'; ++i){}
+    if( i>iInput ){
+      tokenizeSegment(v->pTokenizer, zInput+iInput, i-iInput, inPhrase,
+                       pQuery);
+    }
+    iInput = i;
+    if( i<nInput ){
+      assert( zInput[i]=='"' );
+      inPhrase = !inPhrase;
+    }
+  }
+
+  if( inPhrase ){
+    /* unmatched quote */
+    queryClear(pQuery);
+    return SQLITE_ERROR;
+  }
+  return SQLITE_OK;
+}
+
+/* Perform a full-text query using the search expression in
+** zInput[0..nInput-1].  Return a list of matching documents
+** in pResult.
+**
+** Queries must match column iColumn.  Or if iColumn>=nColumn
+** they are allowed to match against any column.
+*/
+static int fulltextQuery(
+  fulltext_vtab *v,      /* The full text index */
+  int iColumn,           /* Match against this column by default */
+  const char *zInput,    /* The query string */
+  int nInput,            /* Number of bytes in zInput[] */
+  DocList **pResult,     /* Write the result doclist here */
+  Query *pQuery          /* Put parsed query string here */
+){
+  int i, iNext, rc;
+  DocList *pLeft = NULL;
+  DocList *pRight, *pNew, *pOr;
+  int nNot = 0;
+  QueryTerm *aTerm;
+
+  rc = parseQuery(v, zInput, nInput, iColumn, pQuery);
+  if( rc!=SQLITE_OK ) return rc;
+
+  /* Merge AND terms. */
+  aTerm = pQuery->pTerms;
+  for(i = 0; i<pQuery->nTerms; i=iNext){
+    if( aTerm[i].isNot ){
+      /* Handle all NOT terms in a separate pass */
+      nNot++;
+      iNext = i + aTerm[i].nPhrase+1;
+      continue;
+    }
+    iNext = i + aTerm[i].nPhrase + 1;
+    rc = docListOfTerm(v, aTerm[i].iColumn, &aTerm[i], &pRight);
+    if( rc ){
+      queryClear(pQuery);
+      return rc;
+    }
+    while( iNext<pQuery->nTerms && aTerm[iNext].isOr ){
+      rc = docListOfTerm(v, aTerm[iNext].iColumn, &aTerm[iNext], &pOr);
+      iNext += aTerm[iNext].nPhrase + 1;
+      if( rc ){
+        queryClear(pQuery);
+        return rc;
+      }
+      pNew = docListNew(DL_DOCIDS);
+      docListOrMerge(pRight, pOr, pNew);
+      docListDelete(pRight);
+      docListDelete(pOr);
+      pRight = pNew;
+    }
+    if( pLeft==0 ){
+      pLeft = pRight;
+    }else{
+      pNew = docListNew(DL_DOCIDS);
+      docListAndMerge(pLeft, pRight, pNew);
+      docListDelete(pRight);
+      docListDelete(pLeft);
+      pLeft = pNew;
+    }
+  }
+
+  if( nNot && pLeft==0 ){
+    /* We do not yet know how to handle a query of only NOT terms */
+    return SQLITE_ERROR;
+  }
+
+  /* Do the EXCEPT terms */
+  for(i=0; i<pQuery->nTerms;  i += aTerm[i].nPhrase + 1){
+    if( !aTerm[i].isNot ) continue;
+    rc = docListOfTerm(v, aTerm[i].iColumn, &aTerm[i], &pRight);
+    if( rc ){
+      queryClear(pQuery);
+      docListDelete(pLeft);
+      return rc;
+    }
+    pNew = docListNew(DL_DOCIDS);
+    docListExceptMerge(pLeft, pRight, pNew);
+    docListDelete(pRight);
+    docListDelete(pLeft);
+    pLeft = pNew;
+  }
+
+  *pResult = pLeft;
+  return rc;
+}
+
+/*
+** This is the xFilter interface for the virtual table.  See
+** the virtual table xFilter method documentation for additional
+** information.
+**
+** If idxNum==QUERY_GENERIC then do a full table scan against
+** the %_content table.
+**
+** If idxNum==QUERY_ROWID then do a rowid lookup for a single entry
+** in the %_content table.
+**
+** If idxNum>=QUERY_FULLTEXT then use the full text index.  The
+** column on the left-hand side of the MATCH operator is column
+** number idxNum-QUERY_FULLTEXT, 0 indexed.  argv[0] is the right-hand
+** side of the MATCH operator.
+*/
+/* TODO(shess) Upgrade the cursor initialization and destruction to
+** account for fulltextFilter() being called multiple times on the
+** same cursor.  The current solution is very fragile.  Apply fix to
+** fts2 as appropriate.
+*/
+static int fulltextFilter(
+  sqlite3_vtab_cursor *pCursor,     /* The cursor used for this query */
+  int idxNum, const char *idxStr,   /* Which indexing scheme to use */
+  int argc, sqlite3_value **argv    /* Arguments for the indexing scheme */
+){
+  fulltext_cursor *c = (fulltext_cursor *) pCursor;
+  fulltext_vtab *v = cursor_vtab(c);
+  int rc;
+  char *zSql;
+
+  TRACE(("FTS1 Filter %p\n",pCursor));
+
+  zSql = sqlite3_mprintf("select rowid, * from %%_content %s",
+                          idxNum==QUERY_GENERIC ? "" : "where rowid=?");
+  sqlite3_finalize(c->pStmt);
+  rc = sql_prepare(v->db, v->zDb, v->zName, &c->pStmt, zSql);
+  sqlite3_free(zSql);
+  if( rc!=SQLITE_OK ) return rc;
+
+  c->iCursorType = idxNum;
+  switch( idxNum ){
+    case QUERY_GENERIC:
+      break;
+
+    case QUERY_ROWID:
+      rc = sqlite3_bind_int64(c->pStmt, 1, sqlite3_value_int64(argv[0]));
+      if( rc!=SQLITE_OK ) return rc;
+      break;
+
+    default:   /* full-text search */
+    {
+      const char *zQuery = (const char *)sqlite3_value_text(argv[0]);
+      DocList *pResult;
+      assert( idxNum<=QUERY_FULLTEXT+v->nColumn);
+      assert( argc==1 );
+      queryClear(&c->q);
+      rc = fulltextQuery(v, idxNum-QUERY_FULLTEXT, zQuery, -1, &pResult, &c->q);
+      if( rc!=SQLITE_OK ) return rc;
+      if( c->result.pDoclist!=NULL ) docListDelete(c->result.pDoclist);
+      readerInit(&c->result, pResult);
+      break;
+    }
+  }
+
+  return fulltextNext(pCursor);
+}
+
+/* This is the xEof method of the virtual table.  The SQLite core
+** calls this routine to find out if it has reached the end of
+** a query's results set.
+*/
+static int fulltextEof(sqlite3_vtab_cursor *pCursor){
+  fulltext_cursor *c = (fulltext_cursor *) pCursor;
+  return c->eof;
+}
+
+/* This is the xColumn method of the virtual table.  The SQLite
+** core calls this method during a query when it needs the value
+** of a column from the virtual table.  This method needs to use
+** one of the sqlite3_result_*() routines to store the requested
+** value back in the pContext.
+*/
+static int fulltextColumn(sqlite3_vtab_cursor *pCursor,
+                          sqlite3_context *pContext, int idxCol){
+  fulltext_cursor *c = (fulltext_cursor *) pCursor;
+  fulltext_vtab *v = cursor_vtab(c);
+
+  if( idxCol<v->nColumn ){
+    sqlite3_value *pVal = sqlite3_column_value(c->pStmt, idxCol+1);
+    sqlite3_result_value(pContext, pVal);
+  }else if( idxCol==v->nColumn ){
+    /* The extra column whose name is the same as the table.
+    ** Return a blob which is a pointer to the cursor
+    */
+    sqlite3_result_blob(pContext, &c, sizeof(c), SQLITE_TRANSIENT);
+  }
+  return SQLITE_OK;
+}
+
+/* This is the xRowid method.  The SQLite core calls this routine to
+** retrive the rowid for the current row of the result set.  The
+** rowid should be written to *pRowid.
+*/
+static int fulltextRowid(sqlite3_vtab_cursor *pCursor, sqlite_int64 *pRowid){
+  fulltext_cursor *c = (fulltext_cursor *) pCursor;
+
+  *pRowid = sqlite3_column_int64(c->pStmt, 0);
+  return SQLITE_OK;
+}
+
+/* Add all terms in [zText] to the given hash table.  If [iColumn] > 0,
+ * we also store positions and offsets in the hash table using the given
+ * column number. */
+static int buildTerms(fulltext_vtab *v, fts1Hash *terms, sqlite_int64 iDocid,
+                      const char *zText, int iColumn){
+  sqlite3_tokenizer *pTokenizer = v->pTokenizer;
+  sqlite3_tokenizer_cursor *pCursor;
+  const char *pToken;
+  int nTokenBytes;
+  int iStartOffset, iEndOffset, iPosition;
+  int rc;
+
+  rc = pTokenizer->pModule->xOpen(pTokenizer, zText, -1, &pCursor);
+  if( rc!=SQLITE_OK ) return rc;
+
+  pCursor->pTokenizer = pTokenizer;
+  while( SQLITE_OK==pTokenizer->pModule->xNext(pCursor,
+                                               &pToken, &nTokenBytes,
+                                               &iStartOffset, &iEndOffset,
+                                               &iPosition) ){
+    DocList *p;
+
+    /* Positions can't be negative; we use -1 as a terminator internally. */
+    if( iPosition<0 ){
+      pTokenizer->pModule->xClose(pCursor);
+      return SQLITE_ERROR;
+    }
+
+    p = fts1HashFind(terms, pToken, nTokenBytes);
+    if( p==NULL ){
+      p = docListNew(DL_DEFAULT);
+      docListAddDocid(p, iDocid);
+      fts1HashInsert(terms, pToken, nTokenBytes, p);
+    }
+    if( iColumn>=0 ){
+      docListAddPosOffset(p, iColumn, iPosition, iStartOffset, iEndOffset);
+    }
+  }
+
+  /* TODO(shess) Check return?  Should this be able to cause errors at
+  ** this point?  Actually, same question about sqlite3_finalize(),
+  ** though one could argue that failure there means that the data is
+  ** not durable.  *ponder*
+  */
+  pTokenizer->pModule->xClose(pCursor);
+  return rc;
+}
+
+/* Update the %_terms table to map the term [pTerm] to the given rowid. */
+static int index_insert_term(fulltext_vtab *v, const char *pTerm, int nTerm,
+                             DocList *d){
+  sqlite_int64 iIndexRow;
+  DocList doclist;
+  int iSegment = 0, rc;
+
+  rc = term_select(v, pTerm, nTerm, iSegment, &iIndexRow, &doclist);
+  if( rc==SQLITE_DONE ){
+    docListInit(&doclist, DL_DEFAULT, 0, 0);
+    docListUpdate(&doclist, d);
+    /* TODO(shess) Consider length(doclist)>CHUNK_MAX? */
+    rc = term_insert(v, NULL, pTerm, nTerm, iSegment, &doclist);
+    goto err;
+  }
+  if( rc!=SQLITE_ROW ) return SQLITE_ERROR;
+
+  docListUpdate(&doclist, d);
+  if( doclist.nData<=CHUNK_MAX ){
+    rc = term_update(v, iIndexRow, &doclist);
+    goto err;
+  }
+
+  /* Doclist doesn't fit, delete what's there, and accumulate
+  ** forward.
+  */
+  rc = term_delete(v, iIndexRow);
+  if( rc!=SQLITE_OK ) goto err;
+
+  /* Try to insert the doclist into a higher segment bucket.  On
+  ** failure, accumulate existing doclist with the doclist from that
+  ** bucket, and put results in the next bucket.
+  */
+  iSegment++;
+  while( (rc=term_insert(v, &iIndexRow, pTerm, nTerm, iSegment,
+                         &doclist))!=SQLITE_OK ){
+    sqlite_int64 iSegmentRow;
+    DocList old;
+    int rc2;
+
+    /* Retain old error in case the term_insert() error was really an
+    ** error rather than a bounced insert.
+    */
+    rc2 = term_select(v, pTerm, nTerm, iSegment, &iSegmentRow, &old);
+    if( rc2!=SQLITE_ROW ) goto err;
+
+    rc = term_delete(v, iSegmentRow);
+    if( rc!=SQLITE_OK ) goto err;
+
+    /* Reusing lowest-number deleted row keeps the index smaller. */
+    if( iSegmentRow<iIndexRow ) iIndexRow = iSegmentRow;
+
+    /* doclist contains the newer data, so accumulate it over old.
+    ** Then steal accumulated data for doclist.
+    */
+    docListAccumulate(&old, &doclist);
+    docListDestroy(&doclist);
+    doclist = old;
+
+    iSegment++;
+  }
+
+ err:
+  docListDestroy(&doclist);
+  return rc;
+}
+
+/* Add doclists for all terms in [pValues] to the hash table [terms]. */
+static int insertTerms(fulltext_vtab *v, fts1Hash *terms, sqlite_int64 iRowid,
+                sqlite3_value **pValues){
+  int i;
+  for(i = 0; i < v->nColumn ; ++i){
+    char *zText = (char*)sqlite3_value_text(pValues[i]);
+    int rc = buildTerms(v, terms, iRowid, zText, i);
+    if( rc!=SQLITE_OK ) return rc;
+  }
+  return SQLITE_OK;
+}
+
+/* Add empty doclists for all terms in the given row's content to the hash
+ * table [pTerms]. */
+static int deleteTerms(fulltext_vtab *v, fts1Hash *pTerms, sqlite_int64 iRowid){
+  const char **pValues;
+  int i;
+
+  int rc = content_select(v, iRowid, &pValues);
+  if( rc!=SQLITE_OK ) return rc;
+
+  for(i = 0 ; i < v->nColumn; ++i) {
+    rc = buildTerms(v, pTerms, iRowid, pValues[i], -1);
+    if( rc!=SQLITE_OK ) break;
+  }
+
+  freeStringArray(v->nColumn, pValues);
+  return SQLITE_OK;
+}
+
+/* Insert a row into the %_content table; set *piRowid to be the ID of the
+ * new row.  Fill [pTerms] with new doclists for the %_term table. */
+static int index_insert(fulltext_vtab *v, sqlite3_value *pRequestRowid,
+                        sqlite3_value **pValues,
+                        sqlite_int64 *piRowid, fts1Hash *pTerms){
+  int rc;
+
+  rc = content_insert(v, pRequestRowid, pValues);  /* execute an SQL INSERT */
+  if( rc!=SQLITE_OK ) return rc;
+  *piRowid = sqlite3_last_insert_rowid(v->db);
+  return insertTerms(v, pTerms, *piRowid, pValues);
+}
+
+/* Delete a row from the %_content table; fill [pTerms] with empty doclists
+ * to be written to the %_term table. */
+static int index_delete(fulltext_vtab *v, sqlite_int64 iRow, fts1Hash *pTerms){
+  int rc = deleteTerms(v, pTerms, iRow);
+  if( rc!=SQLITE_OK ) return rc;
+  return content_delete(v, iRow);  /* execute an SQL DELETE */
+}
+
+/* Update a row in the %_content table; fill [pTerms] with new doclists for the
+ * %_term table. */
+static int index_update(fulltext_vtab *v, sqlite_int64 iRow,
+                        sqlite3_value **pValues, fts1Hash *pTerms){
+  /* Generate an empty doclist for each term that previously appeared in this
+   * row. */
+  int rc = deleteTerms(v, pTerms, iRow);
+  if( rc!=SQLITE_OK ) return rc;
+
+  rc = content_update(v, pValues, iRow);  /* execute an SQL UPDATE */
+  if( rc!=SQLITE_OK ) return rc;
+
+  /* Now add positions for terms which appear in the updated row. */
+  return insertTerms(v, pTerms, iRow, pValues);
+}
+
+/* This function implements the xUpdate callback; it's the top-level entry
+ * point for inserting, deleting or updating a row in a full-text table. */
+static int fulltextUpdate(sqlite3_vtab *pVtab, int nArg, sqlite3_value **ppArg,
+                   sqlite_int64 *pRowid){
+  fulltext_vtab *v = (fulltext_vtab *) pVtab;
+  fts1Hash terms;   /* maps term string -> PosList */
+  int rc;
+  fts1HashElem *e;
+
+  TRACE(("FTS1 Update %p\n", pVtab));
+  
+  fts1HashInit(&terms, FTS1_HASH_STRING, 1);
+
+  if( nArg<2 ){
+    rc = index_delete(v, sqlite3_value_int64(ppArg[0]), &terms);
+  } else if( sqlite3_value_type(ppArg[0]) != SQLITE_NULL ){
+    /* An update:
+     * ppArg[0] = old rowid
+     * ppArg[1] = new rowid
+     * ppArg[2..2+v->nColumn-1] = values
+     * ppArg[2+v->nColumn] = value for magic column (we ignore this)
+     */
+    sqlite_int64 rowid = sqlite3_value_int64(ppArg[0]);
+    if( sqlite3_value_type(ppArg[1]) != SQLITE_INTEGER ||
+      sqlite3_value_int64(ppArg[1]) != rowid ){
+      rc = SQLITE_ERROR;  /* we don't allow changing the rowid */
+    } else {
+      assert( nArg==2+v->nColumn+1);
+      rc = index_update(v, rowid, &ppArg[2], &terms);
+    }
+  } else {
+    /* An insert:
+     * ppArg[1] = requested rowid
+     * ppArg[2..2+v->nColumn-1] = values
+     * ppArg[2+v->nColumn] = value for magic column (we ignore this)
+     */
+    assert( nArg==2+v->nColumn+1);
+    rc = index_insert(v, ppArg[1], &ppArg[2], pRowid, &terms);
+  }
+
+  if( rc==SQLITE_OK ){
+    /* Write updated doclists to disk. */
+    for(e=fts1HashFirst(&terms); e; e=fts1HashNext(e)){
+      DocList *p = fts1HashData(e);
+      rc = index_insert_term(v, fts1HashKey(e), fts1HashKeysize(e), p);
+      if( rc!=SQLITE_OK ) break;
+    }
+  }
+
+  /* clean up */
+  for(e=fts1HashFirst(&terms); e; e=fts1HashNext(e)){
+    DocList *p = fts1HashData(e);
+    docListDelete(p);
+  }
+  fts1HashClear(&terms);
+
+  return rc;
+}
+
+/*
+** Implementation of the snippet() function for FTS1
+*/
+static void snippetFunc(
+  sqlite3_context *pContext,
+  int argc,
+  sqlite3_value **argv
+){
+  fulltext_cursor *pCursor;
+  if( argc<1 ) return;
+  if( sqlite3_value_type(argv[0])!=SQLITE_BLOB ||
+      sqlite3_value_bytes(argv[0])!=sizeof(pCursor) ){
+    sqlite3_result_error(pContext, "illegal first argument to html_snippet",-1);
+  }else{
+    const char *zStart = "<b>";
+    const char *zEnd = "</b>";
+    const char *zEllipsis = "<b>...</b>";
+    memcpy(&pCursor, sqlite3_value_blob(argv[0]), sizeof(pCursor));
+    if( argc>=2 ){
+      zStart = (const char*)sqlite3_value_text(argv[1]);
+      if( argc>=3 ){
+        zEnd = (const char*)sqlite3_value_text(argv[2]);
+        if( argc>=4 ){
+          zEllipsis = (const char*)sqlite3_value_text(argv[3]);
+        }
+      }
+    }
+    snippetAllOffsets(pCursor);
+    snippetText(pCursor, zStart, zEnd, zEllipsis);
+    sqlite3_result_text(pContext, pCursor->snippet.zSnippet,
+                        pCursor->snippet.nSnippet, SQLITE_STATIC);
+  }
+}
+
+/*
+** Implementation of the offsets() function for FTS1
+*/
+static void snippetOffsetsFunc(
+  sqlite3_context *pContext,
+  int argc,
+  sqlite3_value **argv
+){
+  fulltext_cursor *pCursor;
+  if( argc<1 ) return;
+  if( sqlite3_value_type(argv[0])!=SQLITE_BLOB ||
+      sqlite3_value_bytes(argv[0])!=sizeof(pCursor) ){
+    sqlite3_result_error(pContext, "illegal first argument to offsets",-1);
+  }else{
+    memcpy(&pCursor, sqlite3_value_blob(argv[0]), sizeof(pCursor));
+    snippetAllOffsets(pCursor);
+    snippetOffsetText(&pCursor->snippet);
+    sqlite3_result_text(pContext,
+                        pCursor->snippet.zOffset, pCursor->snippet.nOffset,
+                        SQLITE_STATIC);
+  }
+}
+
+/*
+** This routine implements the xFindFunction method for the FTS1
+** virtual table.
+*/
+static int fulltextFindFunction(
+  sqlite3_vtab *pVtab,
+  int nArg,
+  const char *zName,
+  void (**pxFunc)(sqlite3_context*,int,sqlite3_value**),
+  void **ppArg
+){
+  if( strcmp(zName,"snippet")==0 ){
+    *pxFunc = snippetFunc;
+    return 1;
+  }else if( strcmp(zName,"offsets")==0 ){
+    *pxFunc = snippetOffsetsFunc;
+    return 1;
+  }
+  return 0;
+}
+
+/*
+** Rename an fts1 table.
+*/
+static int fulltextRename(
+  sqlite3_vtab *pVtab,
+  const char *zName
+){
+  fulltext_vtab *p = (fulltext_vtab *)pVtab;
+  int rc = SQLITE_NOMEM;
+  char *zSql = sqlite3_mprintf(
+    "ALTER TABLE %Q.'%q_content'  RENAME TO '%q_content';"
+    "ALTER TABLE %Q.'%q_term' RENAME TO '%q_term';"
+    , p->zDb, p->zName, zName
+    , p->zDb, p->zName, zName
+  );
+  if( zSql ){
+    rc = sqlite3_exec(p->db, zSql, 0, 0, 0);
+    sqlite3_free(zSql);
+  }
+  return rc;
+}
+
+static const sqlite3_module fulltextModule = {
+  /* iVersion      */ 0,
+  /* xCreate       */ fulltextCreate,
+  /* xConnect      */ fulltextConnect,
+  /* xBestIndex    */ fulltextBestIndex,
+  /* xDisconnect   */ fulltextDisconnect,
+  /* xDestroy      */ fulltextDestroy,
+  /* xOpen         */ fulltextOpen,
+  /* xClose        */ fulltextClose,
+  /* xFilter       */ fulltextFilter,
+  /* xNext         */ fulltextNext,
+  /* xEof          */ fulltextEof,
+  /* xColumn       */ fulltextColumn,
+  /* xRowid        */ fulltextRowid,
+  /* xUpdate       */ fulltextUpdate,
+  /* xBegin        */ 0, 
+  /* xSync         */ 0,
+  /* xCommit       */ 0,
+  /* xRollback     */ 0,
+  /* xFindFunction */ fulltextFindFunction,
+  /* xRename       */ fulltextRename,
+};
+
+int sqlite3Fts1Init(sqlite3 *db){
+  sqlite3_overload_function(db, "snippet", -1);
+  sqlite3_overload_function(db, "offsets", -1);
+  return sqlite3_create_module(db, "fts1", &fulltextModule, 0);
+}
+
+#if !SQLITE_CORE
+int sqlite3_extension_init(sqlite3 *db, char **pzErrMsg,
+                           const sqlite3_api_routines *pApi){
+  SQLITE_EXTENSION_INIT2(pApi)
+  return sqlite3Fts1Init(db);
+}
+#endif
+
+#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS1) */