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libdb/lang/sql/sqlite/ext/fts1/fulltext.c
Gregory Burd eff277ac23 Release 5.2.28 on 6/10/2011
2011-09-13 13:44:24 -04:00

1496 lines
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/* The author disclaims copyright to this source code.
*
* This is an SQLite module implementing full-text search.
*/
#include <assert.h>
#if !defined(__APPLE__)
#include <malloc.h>
#else
#include <stdlib.h>
#endif
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include "fulltext.h"
#include "ft_hash.h"
#include "tokenizer.h"
#include "sqlite3.h"
#include "sqlite3ext.h"
SQLITE_EXTENSION_INIT1
/* utility functions */
/* 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 1, or 0 for end)
* 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 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.
*/
typedef enum DocListType {
DL_DOCIDS, /* docids only */
DL_POSITIONS, /* docids + positions */
DL_POSITIONS_OFFSETS /* docids + positions + offsets */
} DocListType;
typedef struct DocList {
char *pData;
int nData;
DocListType iType;
int iLastPos; /* the last position written */
int iLastOffset; /* the last start offset written */
} DocList;
/* 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->iLastPos = 0;
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);
d->iLastPos = 0;
}
/* Add a position to the last position list in a doclist. */
static void docListAddPos(DocList *d, int iPos){
assert( d->iType>=DL_POSITIONS );
appendVarint(d, iPos-d->iLastPos+1);
d->iLastPos = iPos;
}
static void docListAddPosOffset(DocList *d, int iPos,
int iStartOffset, int iEndOffset){
assert( d->iType==DL_POSITIONS_OFFSETS );
docListAddPos(d, iPos);
appendVarint(d, iStartOffset-d->iLastOffset);
d->iLastOffset = iStartOffset;
appendVarint(d, iEndOffset-iStartOffset);
}
/* Terminate the last position list in the given doclist. */
static void docListAddEndPos(DocList *d){
appendVarint(d, 0);
}
typedef struct DocListReader {
DocList *pDoclist;
char *p;
int iLastPos; /* the last position read */
} DocListReader;
static void readerInit(DocListReader *r, DocList *pDoclist){
r->pDoclist = pDoclist;
if( pDoclist!=NULL ){
r->p = pDoclist->pData;
}
r->iLastPos = 0;
}
static int readerAtEnd(DocListReader *pReader){
return 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( !readerAtEnd(pReader) );
getVarint(pReader->p, &ret);
return ret;
}
/* Read the next docid. */
static sqlite_int64 readDocid(DocListReader *pReader){
sqlite_int64 ret;
assert( !readerAtEnd(pReader) );
pReader->p += getVarint(pReader->p, &ret);
pReader->iLastPos = 0;
return ret;
}
/* Read the next position from a position list.
* Returns the position, or -1 at the end of the list. */
static int readPosition(DocListReader *pReader){
int i;
int iType = pReader->pDoclist->iType;
assert( iType>=DL_POSITIONS );
assert( !readerAtEnd(pReader) );
pReader->p += getVarint32(pReader->p, &i);
if( i==0 ){
pReader->iLastPos = -1;
return -1;
}
pReader->iLastPos += ((int) i)-1;
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);
}
return pReader->iLastPos;
}
/* Skip past the end of a position list. */
static void skipPositionList(DocListReader *pReader){
while( readPosition(pReader)!=-1 )
;
}
/* Skip over a docid, including its position list if the doclist has
* positions. */
static void skipDocument(DocListReader *pReader){
readDocid(pReader);
if( pReader->pDoclist->iType >= DL_POSITIONS ){
skipPositionList(pReader);
}
}
static sqlite_int64 firstDocid(DocList *d){
DocListReader r;
readerInit(&r, d);
return readDocid(&r);
}
/* Doclist multi-tool. Pass pUpdate==NULL to delete the indicated docid;
* otherwise pUpdate, which must contain only the single docid [iDocid], is
* inserted (if not present) or updated (if already present). */
static int docListUpdate(DocList *d, sqlite_int64 iDocid, DocList *pUpdate){
int modified = 0;
DocListReader reader;
char *p;
if( pUpdate!=NULL ){
assert( d->iType==pUpdate->iType);
assert( iDocid==firstDocid(pUpdate) );
}
readerInit(&reader, d);
while( !readerAtEnd(&reader) && peekDocid(&reader)<iDocid ){
skipDocument(&reader);
}
p = reader.p;
/* Delete if there is a matching element. */
if( !readerAtEnd(&reader) && iDocid==peekDocid(&reader) ){
skipDocument(&reader);
memmove(p, reader.p, docListEnd(d) - reader.p);
d->nData -= (reader.p - p);
modified = 1;
}
/* Insert if indicated. */
if( pUpdate!=NULL ){
int iDoclist = p-d->pData;
docListAddEndPos(pUpdate);
d->pData = realloc(d->pData, d->nData+pUpdate->nData);
p = d->pData + iDoclist;
memmove(p+pUpdate->nData, p, docListEnd(d) - p);
memcpy(p, pUpdate->pData, pUpdate->nData);
d->nData += pUpdate->nData;
modified = 1;
}
return modified;
}
/* Split the second half of doclist d into a separate doclist d2. Returns 1
* if successful, or 0 if d contains a single document and hence can't be
* split. */
static int docListSplit(DocList *d, DocList *d2){
const char *pSplitPoint = d->pData + d->nData / 2;
DocListReader reader;
readerInit(&reader, d);
while( reader.p<pSplitPoint ){
skipDocument(&reader);
}
if( readerAtEnd(&reader) ) return 0;
docListInit(d2, d->iType, reader.p, docListEnd(d) - reader.p);
d->nData = reader.p - d->pData;
d->pData = realloc(d->pData, d->nData);
return 1;
}
/* A DocListMerge computes the AND of an in-memory DocList [in] and a chunked
* on-disk doclist, resulting in another in-memory DocList [out]. [in]
* and [out] may or may not store position information according to the
* caller's wishes. The on-disk doclist always comes with positions.
*
* The caller must read each chunk of the on-disk doclist in succession and
* pass it to mergeBlock().
*
* If [in] has positions, then the merge output contains only documents with
* matching positions in the two input doclists. If [in] does not have
* positions, then the merge output contains all documents common to the two
* input doclists.
*
* If [in] is NULL, then the on-disk doclist is copied to [out] directly.
*
* A merge is performed using an integer [iOffset] provided by the caller.
* [iOffset] is subtracted from each position in the on-disk doclist for the
* purpose of position comparison; this is helpful in implementing phrase
* searches.
*
* A DocListMerge is not yet able to propagate offsets through query
* processing; we should add that capability soon.
*/
typedef struct DocListMerge {
DocListReader in;
DocList *pOut;
int iOffset;
} DocListMerge;
static void mergeInit(DocListMerge *m,
DocList *pIn, int iOffset, DocList *pOut){
readerInit(&m->in, pIn);
m->pOut = pOut;
m->iOffset = iOffset;
/* can't handle offsets yet */
assert( pIn==NULL || pIn->iType <= DL_POSITIONS );
assert( pOut->iType <= DL_POSITIONS );
}
/* A helper function for mergeBlock(), below. Merge the position lists
* pointed to by m->in and pBlockReader.
* If the merge matches, write [iDocid] to m->pOut; if m->pOut
* has positions then write all matching positions as well. */
static void mergePosList(DocListMerge *m, sqlite_int64 iDocid,
DocListReader *pBlockReader){
int block_pos = readPosition(pBlockReader);
int in_pos = readPosition(&m->in);
int match = 0;
while( block_pos!=-1 || in_pos!=-1 ){
if( block_pos-m->iOffset==in_pos ){
if( !match ){
docListAddDocid(m->pOut, iDocid);
match = 1;
}
if( m->pOut->iType >= DL_POSITIONS ){
docListAddPos(m->pOut, in_pos);
}
block_pos = readPosition(pBlockReader);
in_pos = readPosition(&m->in);
} else if( in_pos==-1 || (block_pos!=-1 && block_pos-m->iOffset<in_pos) ){
block_pos = readPosition(pBlockReader);
} else {
in_pos = readPosition(&m->in);
}
}
if( m->pOut->iType >= DL_POSITIONS && match ){
docListAddEndPos(m->pOut);
}
}
/* Merge one block of an on-disk doclist into a DocListMerge. */
static void mergeBlock(DocListMerge *m, DocList *pBlock){
DocListReader blockReader;
assert( pBlock->iType >= DL_POSITIONS );
readerInit(&blockReader, pBlock);
while( !readerAtEnd(&blockReader) ){
sqlite_int64 iDocid = readDocid(&blockReader);
if( m->in.pDoclist!=NULL ){
while( 1 ){
if( readerAtEnd(&m->in) ) return; /* nothing more to merge */
if( peekDocid(&m->in)>=iDocid ) break;
skipDocument(&m->in);
}
if( peekDocid(&m->in)>iDocid ){ /* [pIn] has no match with iDocid */
skipPositionList(&blockReader); /* skip this docid in the block */
continue;
}
readDocid(&m->in);
}
/* We have a document match. */
if( m->in.pDoclist==NULL || m->in.pDoclist->iType < DL_POSITIONS ){
/* We don't need to do a poslist merge. */
docListAddDocid(m->pOut, iDocid);
if( m->pOut->iType >= DL_POSITIONS ){
/* Copy all positions to the output doclist. */
while( 1 ){
int pos = readPosition(&blockReader);
if( pos==-1 ) break;
docListAddPos(m->pOut, pos);
}
docListAddEndPos(m->pOut);
} else skipPositionList(&blockReader);
continue;
}
mergePosList(m, iDocid, &blockReader);
}
}
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
* 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 *zName){
const char *p;
size_t len = 0;
size_t nName = strlen(zName);
char *result;
char *r;
/* first compute length needed */
for(p = zFormat ; *p ; ++p){
len += (*p=='%' ? nName : 1);
}
len += 1; /* for null terminator */
r = result = malloc(len);
for(p = zFormat; *p; ++p){
if( *p=='%' ){
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 *zName, const char *zFormat){
char *zCommand = string_format(zFormat, zName);
int rc = sqlite3_exec(db, zCommand, NULL, 0, NULL);
free(zCommand);
return rc;
}
static int sql_prepare(sqlite3 *db, const char *zName, sqlite3_stmt **ppStmt,
const char *zFormat){
char *zCommand = string_format(zFormat, zName);
int rc = sqlite3_prepare(db, zCommand, -1, ppStmt, NULL);
free(zCommand);
return rc;
}
/* end utility functions */
#define QUERY_GENERIC 0
#define QUERY_FULLTEXT 1
#define CHUNK_MAX 1024
typedef enum fulltext_statement {
CONTENT_INSERT_STMT,
CONTENT_SELECT_STMT,
CONTENT_DELETE_STMT,
TERM_SELECT_STMT,
TERM_CHUNK_SELECT_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 *fulltext_zStatement[MAX_STMT] = {
/* CONTENT_INSERT */ "insert into %_content (rowid, content) values (?, ?)",
/* CONTENT_SELECT */ "select content from %_content where rowid = ?",
/* CONTENT_DELETE */ "delete from %_content where rowid = ?",
/* TERM_SELECT */
"select rowid, doclist from %_term where term = ? and first = ?",
/* TERM_CHUNK_SELECT */
"select max(first) from %_term where term = ? and first <= ?",
/* TERM_INSERT */
"insert into %_term (term, first, doclist) values (?, ?, ?)",
/* TERM_UPDATE */ "update %_term set doclist = ? where rowid = ?",
/* TERM_DELETE */ "delete from %_term where rowid = ?",
};
typedef struct fulltext_vtab {
sqlite3_vtab base;
sqlite3 *db;
const char *zName; /* virtual table name */
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];
} fulltext_vtab;
typedef struct fulltext_cursor {
sqlite3_vtab_cursor base;
int iCursorType; /* QUERY_GENERIC or QUERY_FULLTEXT */
sqlite3_stmt *pStmt;
int eof;
/* The following is used only when iCursorType == QUERY_FULLTEXT. */
DocListReader result;
} fulltext_cursor;
static struct fulltext_vtab *cursor_vtab(fulltext_cursor *c){
return (fulltext_vtab *) c->base.pVtab;
}
static sqlite3_module fulltextModule; /* forward declaration */
/* 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 ){
int rc = sql_prepare(v->db, v->zName, &v->pFulltextStatements[iStmt],
fulltext_zStatement[iStmt]);
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 ){
sqlite3_stmt *pNewStmt;
if( rc==SQLITE_BUSY ) continue;
if( rc!=SQLITE_ERROR ) return rc;
rc = sqlite3_reset(s);
if( rc!=SQLITE_SCHEMA ) return SQLITE_ERROR;
v->pFulltextStatements[iStmt] = NULL; /* Still in s */
rc = sql_get_statement(v, iStmt, &pNewStmt);
if( rc!=SQLITE_OK ) goto err;
*ppStmt = pNewStmt;
rc = sqlite3_transfer_bindings(s, pNewStmt);
if( rc!=SQLITE_OK ) goto err;
rc = sqlite3_finalize(s);
if( rc!=SQLITE_OK ) return rc;
s = pNewStmt;
}
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, content) values ([rowid], [zContent]) */
static int content_insert(fulltext_vtab *v, sqlite3_value *rowid,
const char *zContent, int nContent){
sqlite3_stmt *s;
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;
rc = sqlite3_bind_text(s, 2, zContent, nContent, SQLITE_STATIC);
if( rc!=SQLITE_OK ) return rc;
return sql_single_step_statement(v, CONTENT_INSERT_STMT, &s);
}
/* select content from %_content where rowid = [iRow]
* The caller must delete the returned string. */
static int content_select(fulltext_vtab *v, sqlite_int64 iRow,
char **pzContent){
sqlite3_stmt *s;
int 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;
*pzContent = string_dup((const char *)sqlite3_column_text(s, 0));
/* 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 ) return SQLITE_OK;
free(*pzContent);
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 = [zTerm] and first = [iFirst]
* If found, returns SQLITE_OK; the caller must free the returned doclist.
* If no rows found, returns SQLITE_ERROR. */
static int term_select(fulltext_vtab *v, const char *zTerm, int nTerm,
sqlite_int64 iFirst,
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, zTerm, nTerm, SQLITE_TRANSIENT);
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3_bind_int64(s, 2, iFirst);
if( rc!=SQLITE_OK ) return rc;
rc = sql_step_statement(v, TERM_SELECT_STMT, &s);
if( rc!=SQLITE_ROW ) return rc==SQLITE_DONE ? SQLITE_ERROR : rc;
*rowid = sqlite3_column_int64(s, 0);
docListInit(out, DL_POSITIONS_OFFSETS,
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_OK : rc;
}
/* select max(first) from %_term where term = [zTerm] and first <= [iFirst]
* If found, returns SQLITE_ROW and result in *piResult; if the query returns
* NULL (meaning no row found) returns SQLITE_DONE.
*/
static int term_chunk_select(fulltext_vtab *v, const char *zTerm, int nTerm,
sqlite_int64 iFirst, sqlite_int64 *piResult){
sqlite3_stmt *s;
int rc = sql_get_statement(v, TERM_CHUNK_SELECT_STMT, &s);
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3_bind_text(s, 1, zTerm, nTerm, SQLITE_STATIC);
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3_bind_int64(s, 2, iFirst);
if( rc!=SQLITE_OK ) return rc;
rc = sql_step_statement(v, TERM_CHUNK_SELECT_STMT, &s);
if( rc!=SQLITE_ROW ) return rc==SQLITE_DONE ? SQLITE_ERROR : rc;
switch( sqlite3_column_type(s, 0) ){
case SQLITE_NULL:
rc = SQLITE_DONE;
break;
case SQLITE_INTEGER:
*piResult = sqlite3_column_int64(s, 0);
break;
default:
return SQLITE_ERROR;
}
/* We expect only one row. We must execute another sqlite3_step()
* to complete the iteration; otherwise the table will remain locked. */
if( sqlite3_step(s) != SQLITE_DONE ) return SQLITE_ERROR;
return rc;
}
/* insert into %_term (term, first, doclist)
values ([zTerm], [iFirst], [doclist]) */
static int term_insert(fulltext_vtab *v, const char *zTerm, int nTerm,
sqlite_int64 iFirst, DocList *doclist){
sqlite3_stmt *s;
int rc = sql_get_statement(v, TERM_INSERT_STMT, &s);
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3_bind_text(s, 1, zTerm, nTerm, SQLITE_STATIC);
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3_bind_int64(s, 2, iFirst);
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3_bind_blob(s, 3, 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);
}
static void fulltext_vtab_destroy(fulltext_vtab *v){
int iStmt;
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((void *) v->zName);
free(v);
}
/* Current interface:
** argv[0] - module name
** argv[1] - database name
** argv[2] - table name
** argv[3] - tokenizer name (optional, a sensible default is provided)
** argv[4..] - passed to tokenizer (optional based on tokenizer)
**/
static int fulltextConnect(sqlite3 *db, void *pAux, int argc, char **argv,
sqlite3_vtab **ppVTab){
int rc;
fulltext_vtab *v;
sqlite3_tokenizer_module *m = NULL;
assert( argc>=3 );
v = (fulltext_vtab *) malloc(sizeof(fulltext_vtab));
/* sqlite will initialize v->base */
v->db = db;
v->zName = string_dup(argv[2]);
v->pTokenizer = NULL;
if( argc==3 ){
get_simple_tokenizer_module(&m);
} else {
/* TODO(shess) For now, add new tokenizers as else if clauses. */
if( !strcmp(argv[3], "simple") ){
get_simple_tokenizer_module(&m);
} else {
assert( "unrecognized tokenizer"==NULL );
}
}
/* TODO(shess) Since tokenization impacts the index, the parameters
** to the tokenizer need to be identical when a persistent virtual
** table is re-created. One solution would be a meta-table to track
** such information in the database. Then we could verify that the
** information is identical on subsequent creates.
*/
/* TODO(shess) Why isn't argv already (const char **)? */
rc = m->xCreate(argc-3, (const char **) (argv+3), &v->pTokenizer);
if( rc!=SQLITE_OK ) return rc;
v->pTokenizer->pModule = m;
/* TODO: verify the existence of backing tables foo_content, foo_term */
rc = sqlite3_declare_vtab(db, "create table x(content text)");
if( rc!=SQLITE_OK ) return rc;
memset(v->pFulltextStatements, 0, sizeof(v->pFulltextStatements));
*ppVTab = &v->base;
return SQLITE_OK;
}
static int fulltextCreate(sqlite3 *db, void *pAux, int argc, char **argv,
sqlite3_vtab **ppVTab){
int rc;
assert( argc>=3 );
/* The %_content table holds the text of each full-text item, 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 count varint-encoded
** "count" token elements (poslist):
** position 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
**
** Additionally, doclist blobs can be chunked into multiple rows,
** using "first" to order the blobs. "first" is simply the first
** docid in the blob.
*/
/*
** NOTE(shess) That last sentence is incorrect in the face of
** deletion, which can leave a doclist that doesn't contain the
** first from that row. I _believe_ this does not matter to the
** operation of the system, but it might be reasonable to update
** appropriately in case this assumption becomes more important.
*/
rc = sql_exec(db, argv[2],
"create table %_content(content text);"
"create table %_term(term text, first integer, doclist blob);"
"create index %_index on %_term(term, first)");
if( rc!=SQLITE_OK ) return rc;
return fulltextConnect(db, pAux, argc, argv, ppVTab);
}
/* Decide how to handle an SQL query.
* At the moment, MATCH queries can include implicit boolean ANDs; we
* haven't implemented phrase searches or OR yet. */
static int fulltextBestIndex(sqlite3_vtab *pVTab, sqlite3_index_info *pInfo){
int i;
for(i=0; i<pInfo->nConstraint; ++i){
const struct sqlite3_index_constraint *pConstraint;
pConstraint = &pInfo->aConstraint[i];
if( pConstraint->iColumn==0 &&
pConstraint->op==SQLITE_INDEX_CONSTRAINT_MATCH &&
pConstraint->usable ){ /* a full-text search */
pInfo->aConstraintUsage[i].argvIndex = 1;
pInfo->aConstraintUsage[i].omit = 1;
pInfo->idxNum = QUERY_FULLTEXT;
pInfo->estimatedCost = 1.0; /* an arbitrary value for now */
return SQLITE_OK;
}
}
pInfo->idxNum = QUERY_GENERIC;
return SQLITE_OK;
}
static int fulltextDisconnect(sqlite3_vtab *pVTab){
fulltext_vtab_destroy((fulltext_vtab *)pVTab);
return SQLITE_OK;
}
static int fulltextDestroy(sqlite3_vtab *pVTab){
fulltext_vtab *v = (fulltext_vtab *)pVTab;
int rc = sql_exec(v->db, v->zName,
"drop table %_content; drop table %_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;
return SQLITE_OK;
}
static int fulltextClose(sqlite3_vtab_cursor *pCursor){
fulltext_cursor *c = (fulltext_cursor *) pCursor;
sqlite3_finalize(c->pStmt);
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;
switch( c->iCursorType ){
case QUERY_GENERIC:
/* 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;
}
case QUERY_FULLTEXT:
rc = sqlite3_reset(c->pStmt);
if( rc!=SQLITE_OK ) return rc;
if( readerAtEnd(&c->result)){
c->eof = 1;
return SQLITE_OK;
}
iDocid = readDocid(&c->result);
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;
default:
assert( 0 );
return SQLITE_ERROR; /* not reached */
}
}
static int term_select_doclist(fulltext_vtab *v, const char *pTerm, int nTerm,
sqlite3_stmt **ppStmt){
int rc;
if( *ppStmt ){
rc = sqlite3_reset(*ppStmt);
} else {
rc = sql_prepare(v->db, v->zName, ppStmt,
"select doclist from %_term where term = ? order by first");
}
if( rc!=SQLITE_OK ) return rc;
rc = sqlite3_bind_text(*ppStmt, 1, pTerm, nTerm, SQLITE_TRANSIENT);
if( rc!=SQLITE_OK ) return rc;
return sqlite3_step(*ppStmt); /* TODO(adamd): handle schema error */
}
/* Read the posting list for [zTerm]; AND it with the doclist [in] to
* produce the doclist [out], using the given offset [iOffset] for phrase
* matching.
* (*pSelect) is used to hold an SQLite statement used inside this function;
* the caller should initialize *pSelect to NULL before the first call.
*/
static int query_merge(fulltext_vtab *v, sqlite3_stmt **pSelect,
const char *zTerm,
DocList *pIn, int iOffset, DocList *out){
int rc;
DocListMerge merge;
if( pIn!=NULL && !pIn->nData ){
/* If [pIn] is already empty, there's no point in reading the
* posting list to AND it in; return immediately. */
return SQLITE_OK;
}
rc = term_select_doclist(v, zTerm, -1, pSelect);
if( rc!=SQLITE_ROW && rc!=SQLITE_DONE ) return rc;
mergeInit(&merge, pIn, iOffset, out);
while( rc==SQLITE_ROW ){
DocList block;
docListInit(&block, DL_POSITIONS_OFFSETS,
sqlite3_column_blob(*pSelect, 0),
sqlite3_column_bytes(*pSelect, 0));
mergeBlock(&merge, &block);
docListDestroy(&block);
rc = sqlite3_step(*pSelect);
if( rc!=SQLITE_ROW && rc!=SQLITE_DONE ){
return rc;
}
}
return SQLITE_OK;
}
typedef struct QueryTerm {
int is_phrase; /* true if this term begins a new phrase */
const char *zTerm;
} QueryTerm;
/* A parsed query.
*
* As an example, parsing the query ["four score" years "new nation"] will
* yield a Query with 5 terms:
* "four", is_phrase = 1
* "score", is_phrase = 0
* "years", is_phrase = 1
* "new", is_phrase = 1
* "nation", is_phrase = 0
*/
typedef struct Query {
int nTerms;
QueryTerm *pTerm;
} Query;
static void query_add(Query *q, int is_phrase, const char *zTerm){
QueryTerm *t;
++q->nTerms;
q->pTerm = realloc(q->pTerm, q->nTerms * sizeof(q->pTerm[0]));
t = &q->pTerm[q->nTerms - 1];
t->is_phrase = is_phrase;
t->zTerm = zTerm;
}
static void query_free(Query *q){
int i;
for(i = 0; i < q->nTerms; ++i){
free((void *) q->pTerm[i].zTerm);
}
free(q->pTerm);
}
static int tokenize_segment(sqlite3_tokenizer *pTokenizer,
const char *zQuery, int in_phrase,
Query *pQuery){
sqlite3_tokenizer_module *pModule = pTokenizer->pModule;
sqlite3_tokenizer_cursor *pCursor;
int is_first = 1;
int rc = pModule->xOpen(pTokenizer, zQuery, -1, &pCursor);
if( rc!=SQLITE_OK ) return rc;
pCursor->pTokenizer = pTokenizer;
while( 1 ){
const char *zToken;
int nToken, iStartOffset, iEndOffset, dummy_pos;
rc = pModule->xNext(pCursor,
&zToken, &nToken,
&iStartOffset, &iEndOffset,
&dummy_pos);
if( rc!=SQLITE_OK ) break;
query_add(pQuery, !in_phrase || is_first, string_dup_n(zToken, nToken));
is_first = 0;
}
return pModule->xClose(pCursor);
}
/* Parse a query string, yielding a Query object. */
static int parse_query(fulltext_vtab *v, const char *zQuery, Query *pQuery){
char *zQuery1 = string_dup(zQuery);
int in_phrase = 0;
char *s = zQuery1;
pQuery->nTerms = 0;
pQuery->pTerm = NULL;
while( *s ){
char *t = s;
while( *t ){
if( *t=='"' ){
*t++ = '\0';
break;
}
++t;
}
if( *s ){
tokenize_segment(v->pTokenizer, s, in_phrase, pQuery);
}
s = t;
in_phrase = !in_phrase;
}
free(zQuery1);
return SQLITE_OK;
}
/* Perform a full-text query; return a list of documents in [pResult]. */
static int fulltext_query(fulltext_vtab *v, const char *zQuery,
DocList **pResult){
Query q;
int phrase_start = -1;
int i;
sqlite3_stmt *pSelect = NULL;
DocList *d = NULL;
int rc = parse_query(v, zQuery, &q);
if( rc!=SQLITE_OK ) return rc;
/* Merge terms. */
for(i = 0 ; i < q.nTerms ; ++i){
/* In each merge step, we need to generate positions whenever we're
* processing a phrase which hasn't ended yet. */
int need_positions = i<q.nTerms-1 && !q.pTerm[i+1].is_phrase;
DocList *next = docListNew(need_positions ? DL_POSITIONS : DL_DOCIDS);
if( q.pTerm[i].is_phrase ){
phrase_start = i;
}
rc = query_merge(v, &pSelect, q.pTerm[i].zTerm, d, i - phrase_start, next);
if( rc!=SQLITE_OK ) break;
if( d!=NULL ){
docListDelete(d);
}
d = next;
}
sqlite3_finalize(pSelect);
query_free(&q);
*pResult = d;
return rc;
}
static int fulltextFilter(sqlite3_vtab_cursor *pCursor,
int idxNum, const char *idxStr,
int argc, sqlite3_value **argv){
fulltext_cursor *c = (fulltext_cursor *) pCursor;
fulltext_vtab *v = cursor_vtab(c);
int rc;
const char *zStatement;
c->iCursorType = idxNum;
switch( idxNum ){
case QUERY_GENERIC:
zStatement = "select rowid, content from %_content";
break;
case QUERY_FULLTEXT: /* full-text search */
{
const char *zQuery = (const char *)sqlite3_value_text(argv[0]);
DocList *pResult;
assert( argc==1 );
rc = fulltext_query(v, zQuery, &pResult);
if( rc!=SQLITE_OK ) return rc;
readerInit(&c->result, pResult);
zStatement = "select rowid, content from %_content where rowid = ?";
break;
}
default:
assert( 0 );
}
rc = sql_prepare(v->db, v->zName, &c->pStmt, zStatement);
if( rc!=SQLITE_OK ) return rc;
return fulltextNext(pCursor);
}
static int fulltextEof(sqlite3_vtab_cursor *pCursor){
fulltext_cursor *c = (fulltext_cursor *) pCursor;
return c->eof;
}
static int fulltextColumn(sqlite3_vtab_cursor *pCursor,
sqlite3_context *pContext, int idxCol){
fulltext_cursor *c = (fulltext_cursor *) pCursor;
const char *s;
assert( idxCol==0 );
s = (const char *) sqlite3_column_text(c->pStmt, 1);
sqlite3_result_text(pContext, s, -1, SQLITE_TRANSIENT);
return SQLITE_OK;
}
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;
}
/* Build a hash table containing all terms in zText. */
static int build_terms(Hash *terms, sqlite3_tokenizer *pTokenizer,
const char *zText, sqlite_int64 iDocid){
sqlite3_tokenizer_cursor *pCursor;
const char *pToken;
int nTokenBytes;
int iStartOffset, iEndOffset, iPosition;
int rc = pTokenizer->pModule->xOpen(pTokenizer, zText, -1, &pCursor);
if( rc!=SQLITE_OK ) return rc;
pCursor->pTokenizer = pTokenizer;
HashInit(terms, HASH_STRING, 1);
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 ) {
rc = SQLITE_ERROR;
goto err;
}
p = HashFind(terms, pToken, nTokenBytes);
if( p==NULL ){
p = docListNew(DL_POSITIONS_OFFSETS);
docListAddDocid(p, iDocid);
HashInsert(terms, pToken, nTokenBytes, p);
}
docListAddPosOffset(p, iPosition, iStartOffset, iEndOffset);
}
err:
/* 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 [zTerm] to the given rowid. */
static int index_insert_term(fulltext_vtab *v, const char *zTerm, int nTerm,
sqlite_int64 iDocid, DocList *p){
sqlite_int64 iFirst;
sqlite_int64 iIndexRow;
DocList doclist;
int rc = term_chunk_select(v, zTerm, nTerm, iDocid, &iFirst);
if( rc==SQLITE_DONE ){
docListInit(&doclist, DL_POSITIONS_OFFSETS, 0, 0);
if( docListUpdate(&doclist, iDocid, p) ){
rc = term_insert(v, zTerm, nTerm, iDocid, &doclist);
docListDestroy(&doclist);
return rc;
}
return SQLITE_OK;
}
if( rc!=SQLITE_ROW ) return SQLITE_ERROR;
/* This word is in the index; add this document ID to its blob. */
rc = term_select(v, zTerm, nTerm, iFirst, &iIndexRow, &doclist);
if( rc!=SQLITE_OK ) return rc;
if( docListUpdate(&doclist, iDocid, p) ){
/* If the blob is too big, split it in half. */
if( doclist.nData>CHUNK_MAX ){
DocList half;
if( docListSplit(&doclist, &half) ){
rc = term_insert(v, zTerm, nTerm, firstDocid(&half), &half);
docListDestroy(&half);
if( rc!=SQLITE_OK ) goto err;
}
}
rc = term_update(v, iIndexRow, &doclist);
}
err:
docListDestroy(&doclist);
return rc;
}
/* Insert a row into the full-text index; set *piRowid to be the ID of the
* new row. */
static int index_insert(fulltext_vtab *v,
sqlite3_value *pRequestRowid, const char *zText,
sqlite_int64 *piRowid){
Hash terms; /* maps term string -> PosList */
HashElem *e;
int rc = content_insert(v, pRequestRowid, zText, -1);
if( rc!=SQLITE_OK ) return rc;
*piRowid = sqlite3_last_insert_rowid(v->db);
if( !zText ) return SQLITE_OK; /* nothing to index */
rc = build_terms(&terms, v->pTokenizer, zText, *piRowid);
if( rc!=SQLITE_OK ) return rc;
for(e=HashFirst(&terms); e; e=HashNext(e)){
DocList *p = HashData(e);
rc = index_insert_term(v, HashKey(e), HashKeysize(e), *piRowid, p);
if( rc!=SQLITE_OK ) break;
}
for(e=HashFirst(&terms); e; e=HashNext(e)){
DocList *p = HashData(e);
docListDelete(p);
}
HashClear(&terms);
return rc;
}
static int index_delete_term(fulltext_vtab *v, const char *zTerm, int nTerm,
sqlite_int64 iDocid){
sqlite_int64 iFirst;
sqlite_int64 iIndexRow;
DocList doclist;
int rc = term_chunk_select(v, zTerm, nTerm, iDocid, &iFirst);
if( rc!=SQLITE_ROW ) return SQLITE_ERROR;
rc = term_select(v, zTerm, nTerm, iFirst, &iIndexRow, &doclist);
if( rc!=SQLITE_OK ) return rc;
if( docListUpdate(&doclist, iDocid, NULL) ){
if( doclist.nData>0 ){
rc = term_update(v, iIndexRow, &doclist);
} else { /* empty posting list */
rc = term_delete(v, iIndexRow);
}
}
docListDestroy(&doclist);
return rc;
}
/* Delete a row from the full-text index. */
static int index_delete(fulltext_vtab *v, sqlite_int64 iRow){
char *zText;
Hash terms;
HashElem *e;
int rc = content_select(v, iRow, &zText);
if( rc!=SQLITE_OK ) return rc;
rc = build_terms(&terms, v->pTokenizer, zText, iRow);
free(zText);
if( rc!=SQLITE_OK ) return rc;
for(e=HashFirst(&terms); e; e=HashNext(e)){
rc = index_delete_term(v, HashKey(e), HashKeysize(e), iRow);
if( rc!=SQLITE_OK ) break;
}
for(e=HashFirst(&terms); e; e=HashNext(e)){
DocList *p = HashData(e);
docListDelete(p);
}
HashClear(&terms);
return content_delete(v, iRow);
}
static int fulltextUpdate(sqlite3_vtab *pVtab, int nArg, sqlite3_value **ppArg,
sqlite_int64 *pRowid){
fulltext_vtab *v = (fulltext_vtab *) pVtab;
if( nArg<2 ){
return index_delete(v, sqlite3_value_int64(ppArg[0]));
}
if( sqlite3_value_type(ppArg[0]) != SQLITE_NULL ){
return SQLITE_ERROR; /* an update; not yet supported */
}
assert( nArg==3 ); /* ppArg[1] = rowid, ppArg[2] = content */
return index_insert(v, ppArg[1],
(const char *)sqlite3_value_text(ppArg[2]), pRowid);
}
static sqlite3_module fulltextModule = {
0,
fulltextCreate,
fulltextConnect,
fulltextBestIndex,
fulltextDisconnect,
fulltextDestroy,
fulltextOpen,
fulltextClose,
fulltextFilter,
fulltextNext,
fulltextEof,
fulltextColumn,
fulltextRowid,
fulltextUpdate
};
int fulltext_init(sqlite3 *db){
return sqlite3_create_module(db, "fulltext", &fulltextModule, 0);
}
#if !SQLITE_CORE
int sqlite3_extension_init(sqlite3 *db, char **pzErrMsg,
const sqlite3_api_routines *pApi){
SQLITE_EXTENSION_INIT2(pApi)
return fulltext_init(db);
}
#endif
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