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0a62730d3f
sqlite/ext/fts3/fts3_write.c
drh 0a62730d3f Updates to snippet() and offsets() functions of FTS3 so that they work 
sanely following an OOM fault.

FossilOrigin-Name: b939a37a8ce296785a300e79ab9d3d87ad91343f
2009-11-28 21:33:21 +00:00

2155 lines
71 KiB
C
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/*
** 2009 Oct 23
**
** The author disclaims copyright to this source code. In place of
** a legal notice, here is a blessing:
**
** May you do good and not evil.
** May you find forgiveness for yourself and forgive others.
** May you share freely, never taking more than you give.
**
******************************************************************************
**
** This file is part of the SQLite FTS3 extension module. Specifically,
** this file contains code to insert, update and delete rows from FTS3
** tables. It also contains code to merge FTS3 b-tree segments. Some
** of the sub-routines used to merge segments are also used by the query
** code in fts3.c.
*/
#if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)
#include "fts3Int.h"
#include <string.h>
#include <assert.h>
#include <stdlib.h>
#define INTERIOR_MAX 2048 /* Soft limit for segment node size */
#define LEAF_MAX 2048 /* Soft limit for segment leaf size */
typedef struct PendingList PendingList;
typedef struct SegmentNode SegmentNode;
typedef struct SegmentWriter SegmentWriter;
/*
** Data structure used while accumulating terms in the pending-terms hash
** table. The hash table entry maps from term (a string) to a malloced
** instance of this structure.
*/
struct PendingList {
int nData;
char *aData;
int nSpace;
sqlite3_int64 iLastDocid;
sqlite3_int64 iLastCol;
sqlite3_int64 iLastPos;
};
/*
** An instance of this structure is used to iterate through the terms on
** a contiguous set of segment b-tree leaf nodes. Although the details of
** this structure are only manipulated by code in this file, opaque handles
** of type Fts3SegReader* are also used by code in fts3.c to iterate through
** terms when querying the full-text index. See functions:
**
** sqlite3Fts3SegReaderNew()
** sqlite3Fts3SegReaderFree()
** sqlite3Fts3SegReaderIterate()
*/
struct Fts3SegReader {
int iIdx; /* Index within level */
sqlite3_int64 iStartBlock;
sqlite3_int64 iEndBlock;
sqlite3_stmt *pStmt; /* SQL Statement to access leaf nodes */
char *aNode; /* Pointer to node data (or NULL) */
int nNode; /* Size of buffer at aNode (or 0) */
int nTermAlloc; /* Allocated size of zTerm buffer */
/* Variables set by fts3SegReaderNext(). These may be read directly
** by the caller. They are valid from the time SegmentReaderNew() returns
** until SegmentReaderNext() returns something other than SQLITE_OK
** (i.e. SQLITE_DONE).
*/
int nTerm; /* Number of bytes in current term */
char *zTerm; /* Pointer to current term */
char *aDoclist; /* Pointer to doclist of current entry */
int nDoclist; /* Size of doclist in current entry */
/* The following variables are used to iterate through the current doclist */
char *pOffsetList;
sqlite3_int64 iDocid;
};
/*
** An instance of this structure is used to create a segment b-tree in the
** database. The internal details of this type are only accessed by the
** following functions:
**
** fts3SegWriterAdd()
** fts3SegWriterFlush()
** fts3SegWriterFree()
*/
struct SegmentWriter {
SegmentNode *pTree; /* Pointer to interior tree structure */
sqlite3_int64 iFirst; /* First slot in %_segments written */
sqlite3_int64 iFree; /* Next free slot in %_segments */
char *zTerm; /* Pointer to previous term buffer */
int nTerm; /* Number of bytes in zTerm */
int nMalloc; /* Size of malloc'd buffer at zMalloc */
char *zMalloc; /* Malloc'd space (possibly) used for zTerm */
int nSize; /* Size of allocation at aData */
int nData; /* Bytes of data in aData */
char *aData; /* Pointer to block from malloc() */
};
/*
** Type SegmentNode is used by the following three functions to create
** the interior part of the segment b+-tree structures (everything except
** the leaf nodes). These functions and type are only ever used by code
** within the fts3SegWriterXXX() family of functions described above.
**
** fts3NodeAddTerm()
** fts3NodeWrite()
** fts3NodeFree()
*/
struct SegmentNode {
SegmentNode *pParent; /* Parent node (or NULL for root node) */
SegmentNode *pRight; /* Pointer to right-sibling */
SegmentNode *pLeftmost; /* Pointer to left-most node of this depth */
int nEntry; /* Number of terms written to node so far */
char *zTerm; /* Pointer to previous term buffer */
int nTerm; /* Number of bytes in zTerm */
int nMalloc; /* Size of malloc'd buffer at zMalloc */
char *zMalloc; /* Malloc'd space (possibly) used for zTerm */
int nData; /* Bytes of valid data so far */
char *aData; /* Node data */
};
/*
** Valid values for the second argument to fts3SqlStmt().
*/
#define SQL_DELETE_CONTENT 0
#define SQL_IS_EMPTY 1
#define SQL_DELETE_ALL_CONTENT 2
#define SQL_DELETE_ALL_SEGMENTS 3
#define SQL_DELETE_ALL_SEGDIR 4
#define SQL_SELECT_CONTENT_BY_ROWID 5
#define SQL_NEXT_SEGMENT_INDEX 6
#define SQL_INSERT_SEGMENTS 7
#define SQL_NEXT_SEGMENTS_ID 8
#define SQL_INSERT_SEGDIR 9
#define SQL_SELECT_LEVEL 10
#define SQL_SELECT_ALL_LEVEL 11
#define SQL_SELECT_LEVEL_COUNT 12
#define SQL_SELECT_SEGDIR_COUNT_MAX 13
#define SQL_DELETE_SEGDIR_BY_LEVEL 14
#define SQL_DELETE_SEGMENTS_RANGE 15
#define SQL_CONTENT_INSERT 16
#define SQL_GET_BLOCK 17
/*
** This function is used to obtain an SQLite prepared statement handle
** for the statement identified by the second argument. If successful,
** *pp is set to the requested statement handle and SQLITE_OK returned.
** Otherwise, an SQLite error code is returned and *pp is set to 0.
**
** If argument apVal is not NULL, then it must point to an array with
** at least as many entries as the requested statement has bound
** parameters. The values are bound to the statements parameters before
** returning.
*/
static int fts3SqlStmt(
Fts3Table *p, /* Virtual table handle */
int eStmt, /* One of the SQL_XXX constants above */
sqlite3_stmt **pp, /* OUT: Statement handle */
sqlite3_value **apVal /* Values to bind to statement */
){
const char *azSql[] = {
/* 0 */ "DELETE FROM %Q.'%q_content' WHERE rowid = ?",
/* 1 */ "SELECT NOT EXISTS(SELECT docid FROM %Q.'%q_content' WHERE rowid!=?)",
/* 2 */ "DELETE FROM %Q.'%q_content'",
/* 3 */ "DELETE FROM %Q.'%q_segments'",
/* 4 */ "DELETE FROM %Q.'%q_segdir'",
/* 5 */ "SELECT * FROM %Q.'%q_content' WHERE rowid=?",
/* 6 */ "SELECT coalesce(max(idx)+1, 0) FROM %Q.'%q_segdir' WHERE level=?",
/* 7 */ "INSERT INTO %Q.'%q_segments'(blockid, block) VALUES(?, ?)",
/* 8 */ "SELECT coalesce(max(blockid)+1, 1) FROM %Q.'%q_segments'",
/* 9 */ "INSERT INTO %Q.'%q_segdir' VALUES(?,?,?,?,?,?)",
/* Return segments in order from oldest to newest.*/
/* 10 */ "SELECT idx, start_block, leaves_end_block, end_block, root "
"FROM %Q.'%q_segdir' WHERE level = ? ORDER BY idx ASC",
/* 11 */ "SELECT idx, start_block, leaves_end_block, end_block, root "
"FROM %Q.'%q_segdir' ORDER BY level DESC, idx ASC",
/* 12 */ "SELECT count(*) FROM %Q.'%q_segdir' WHERE level = ?",
/* 13 */ "SELECT count(*), max(level) FROM %Q.'%q_segdir'",
/* 14 */ "DELETE FROM %Q.'%q_segdir' WHERE level = ?",
/* 15 */ "DELETE FROM %Q.'%q_segments' WHERE blockid BETWEEN ? AND ?",
/* 16 */ "INSERT INTO %Q.'%q_content' VALUES(%z)",
/* 17 */ "SELECT block FROM %Q.'%q_segments' WHERE blockid = ?",
};
int rc = SQLITE_OK;
sqlite3_stmt *pStmt;
assert( SizeofArray(azSql)==SizeofArray(p->aStmt) );
assert( eStmt<SizeofArray(azSql) && eStmt>=0 );
pStmt = p->aStmt[eStmt];
if( !pStmt ){
char *zSql;
if( eStmt==SQL_CONTENT_INSERT ){
int i; /* Iterator variable */
char *zVarlist; /* The "?, ?, ..." string */
zVarlist = (char *)sqlite3_malloc(2*p->nColumn+2);
if( !zVarlist ){
*pp = 0;
return SQLITE_NOMEM;
}
zVarlist[0] = '?';
zVarlist[p->nColumn*2+1] = '\0';
for(i=1; i<=p->nColumn; i++){
zVarlist[i*2-1] = ',';
zVarlist[i*2] = '?';
}
zSql = sqlite3_mprintf(azSql[eStmt], p->zDb, p->zName, zVarlist);
}else{
zSql = sqlite3_mprintf(azSql[eStmt], p->zDb, p->zName);
}
if( !zSql ){
rc = SQLITE_NOMEM;
}else{
rc = sqlite3_prepare_v2(p->db, zSql, -1, &pStmt, NULL);
sqlite3_free(zSql);
assert( rc==SQLITE_OK || pStmt==0 );
p->aStmt[eStmt] = pStmt;
}
}
if( apVal ){
int i;
int nParam = sqlite3_bind_parameter_count(pStmt);
for(i=0; rc==SQLITE_OK && i<nParam; i++){
rc = sqlite3_bind_value(pStmt, i+1, apVal[i]);
}
}
*pp = pStmt;
return rc;
}
/*
** Similar to fts3SqlStmt(). Except, after binding the parameters in
** array apVal[] to the SQL statement identified by eStmt, the statement
** is executed.
**
** Returns SQLITE_OK if the statement is successfully executed, or an
** SQLite error code otherwise.
*/
static int fts3SqlExec(Fts3Table *p, int eStmt, sqlite3_value **apVal){
sqlite3_stmt *pStmt;
int rc = fts3SqlStmt(p, eStmt, &pStmt, apVal);
if( rc==SQLITE_OK ){
sqlite3_step(pStmt);
rc = sqlite3_reset(pStmt);
}
return rc;
}
/*
** Read a single block from the %_segments table. If the specified block
** does not exist, return SQLITE_CORRUPT. If some other error (malloc, IO
** etc.) occurs, return the appropriate SQLite error code.
**
** Otherwise, if successful, set *pzBlock to point to a buffer containing
** the block read from the database, and *pnBlock to the size of the read
** block in bytes.
**
** WARNING: The returned buffer is only valid until the next call to
** sqlite3Fts3ReadBlock().
*/
int sqlite3Fts3ReadBlock(
Fts3Table *p,
sqlite3_int64 iBlock,
char const **pzBlock,
int *pnBlock
){
sqlite3_stmt *pStmt;
int rc = fts3SqlStmt(p, SQL_GET_BLOCK, &pStmt, 0);
if( rc!=SQLITE_OK ) return rc;
sqlite3_reset(pStmt);
sqlite3_bind_int64(pStmt, 1, iBlock);
rc = sqlite3_step(pStmt);
if( rc!=SQLITE_ROW ){
return SQLITE_CORRUPT;
}
*pnBlock = sqlite3_column_bytes(pStmt, 0);
*pzBlock = (char *)sqlite3_column_blob(pStmt, 0);
if( !*pzBlock ){
return SQLITE_NOMEM;
}
return SQLITE_OK;
}
/*
** Set *ppStmt to a statement handle that may be used to iterate through
** all rows in the %_segdir table, from oldest to newest. If successful,
** return SQLITE_OK. If an error occurs while preparing the statement,
** return an SQLite error code.
**
** There is only ever one instance of this SQL statement compiled for
** each FTS3 table.
**
** The statement returns the following columns from the %_segdir table:
**
** 0: idx
** 1: start_block
** 2: leaves_end_block
** 3: end_block
** 4: root
*/
int sqlite3Fts3AllSegdirs(Fts3Table *p, sqlite3_stmt **ppStmt){
return fts3SqlStmt(p, SQL_SELECT_ALL_LEVEL, ppStmt, 0);
}
/*
** Append a single varint to a PendingList buffer. SQLITE_OK is returned
** if successful, or an SQLite error code otherwise.
**
** This function also serves to allocate the PendingList structure itself.
** For example, to create a new PendingList structure containing two
** varints:
**
** PendingList *p = 0;
** fts3PendingListAppendVarint(&p, 1);
** fts3PendingListAppendVarint(&p, 2);
*/
static int fts3PendingListAppendVarint(
PendingList **pp, /* IN/OUT: Pointer to PendingList struct */
sqlite3_int64 i /* Value to append to data */
){
PendingList *p = *pp;
/* Allocate or grow the PendingList as required. */
if( !p ){
p = sqlite3_malloc(sizeof(*p) + 100);
if( !p ){
return SQLITE_NOMEM;
}
p->nSpace = 100;
p->aData = (char *)&p[1];
p->nData = 0;
}
else if( p->nData+FTS3_VARINT_MAX+1>p->nSpace ){
int nNew = p->nSpace * 2;
p = sqlite3_realloc(p, sizeof(*p) + nNew);
if( !p ){
sqlite3_free(*pp);
*pp = 0;
return SQLITE_NOMEM;
}
p->nSpace = nNew;
p->aData = (char *)&p[1];
}
/* Append the new serialized varint to the end of the list. */
p->nData += sqlite3Fts3PutVarint(&p->aData[p->nData], i);
p->aData[p->nData] = '\0';
*pp = p;
return SQLITE_OK;
}
/*
** Add a docid/column/position entry to a PendingList structure. Non-zero
** is returned if the structure is sqlite3_realloced as part of adding
** the entry. Otherwise, zero.
**
** If an OOM error occurs, *pRc is set to SQLITE_NOMEM before returning.
** Zero is always returned in this case. Otherwise, if no OOM error occurs,
** it is set to SQLITE_OK.
*/
static int fts3PendingListAppend(
PendingList **pp, /* IN/OUT: PendingList structure */
sqlite3_int64 iDocid, /* Docid for entry to add */
sqlite3_int64 iCol, /* Column for entry to add */
sqlite3_int64 iPos, /* Position of term for entry to add */
int *pRc /* OUT: Return code */
){
PendingList *p = *pp;
int rc = SQLITE_OK;
assert( !p || p->iLastDocid<=iDocid );
if( !p || p->iLastDocid!=iDocid ){
sqlite3_int64 iDelta = iDocid - (p ? p->iLastDocid : 0);
if( p ){
assert( p->nData<p->nSpace );
assert( p->aData[p->nData]==0 );
p->nData++;
}
if( SQLITE_OK!=(rc = fts3PendingListAppendVarint(&p, iDelta)) ){
goto pendinglistappend_out;
}
p->iLastCol = -1;
p->iLastPos = 0;
p->iLastDocid = iDocid;
}
if( iCol>0 && p->iLastCol!=iCol ){
if( SQLITE_OK!=(rc = fts3PendingListAppendVarint(&p, 1))
|| SQLITE_OK!=(rc = fts3PendingListAppendVarint(&p, iCol))
){
goto pendinglistappend_out;
}
p->iLastCol = iCol;
p->iLastPos = 0;
}
if( iCol>=0 ){
assert( iPos>p->iLastPos || (iPos==0 && p->iLastPos==0) );
rc = fts3PendingListAppendVarint(&p, 2+iPos-p->iLastPos);
if( rc==SQLITE_OK ){
p->iLastPos = iPos;
}
}
pendinglistappend_out:
*pRc = rc;
if( p!=*pp ){
*pp = p;
return 1;
}
return 0;
}
/*
** Tokenize the nul-terminated string zText and add all tokens to the
** pending-terms hash-table. The docid used is that currently stored in
** p->iPrevDocid, and the column is specified by argument iCol.
**
** If successful, SQLITE_OK is returned. Otherwise, an SQLite error code.
*/
static int fts3PendingTermsAdd(Fts3Table *p, const char *zText, int iCol){
int rc;
int iStart;
int iEnd;
int iPos;
char const *zToken;
int nToken;
sqlite3_tokenizer *pTokenizer = p->pTokenizer;
sqlite3_tokenizer_module const *pModule = pTokenizer->pModule;
sqlite3_tokenizer_cursor *pCsr;
int (*xNext)(sqlite3_tokenizer_cursor *pCursor,
const char**,int*,int*,int*,int*);
assert( pTokenizer && pModule );
rc = pModule->xOpen(pTokenizer, zText, -1, &pCsr);
if( rc!=SQLITE_OK ){
return rc;
}
pCsr->pTokenizer = pTokenizer;
xNext = pModule->xNext;
while( SQLITE_OK==rc
&& SQLITE_OK==(rc = xNext(pCsr, &zToken, &nToken, &iStart, &iEnd, &iPos))
){
PendingList *pList;
/* Positions cannot be negative; we use -1 as a terminator internally.
** Tokens must have a non-zero length.
*/
if( iPos<0 || !zToken || nToken<=0 ){
rc = SQLITE_ERROR;
break;
}
pList = (PendingList *)fts3HashFind(&p->pendingTerms, zToken, nToken);
if( pList ){
p->nPendingData -= (pList->nData + nToken + sizeof(Fts3HashElem));
}
if( fts3PendingListAppend(&pList, p->iPrevDocid, iCol, iPos, &rc) ){
if( pList==fts3HashInsert(&p->pendingTerms, zToken, nToken, pList) ){
/* Malloc failed while inserting the new entry. This can only
** happen if there was no previous entry for this token.
*/
assert( 0==fts3HashFind(&p->pendingTerms, zToken, nToken) );
sqlite3_free(pList);
rc = SQLITE_NOMEM;
}
}
if( rc==SQLITE_OK ){
p->nPendingData += (pList->nData + nToken + sizeof(Fts3HashElem));
}
}
pModule->xClose(pCsr);
return (rc==SQLITE_DONE ? SQLITE_OK : rc);
}
/*
** Calling this function indicates that subsequent calls to
** fts3PendingTermsAdd() are to add term/position-list pairs for the
** contents of the document with docid iDocid.
*/
static int fts3PendingTermsDocid(Fts3Table *p, sqlite_int64 iDocid){
/* TODO(shess) Explore whether partially flushing the buffer on
** forced-flush would provide better performance. I suspect that if
** we ordered the doclists by size and flushed the largest until the
** buffer was half empty, that would let the less frequent terms
** generate longer doclists.
*/
if( iDocid<=p->iPrevDocid || p->nPendingData>FTS3_MAX_PENDING_DATA ){
int rc = sqlite3Fts3PendingTermsFlush(p);
if( rc!=SQLITE_OK ) return rc;
}
p->iPrevDocid = iDocid;
return SQLITE_OK;
}
void sqlite3Fts3PendingTermsClear(Fts3Table *p){
Fts3HashElem *pElem;
for(pElem=fts3HashFirst(&p->pendingTerms); pElem; pElem=fts3HashNext(pElem)){
sqlite3_free(fts3HashData(pElem));
}
fts3HashClear(&p->pendingTerms);
p->nPendingData = 0;
}
/*
** This function is called by the xUpdate() method as part of an INSERT
** operation. It adds entries for each term in the new record to the
** pendingTerms hash table.
**
** Argument apVal is the same as the similarly named argument passed to
** fts3InsertData(). Parameter iDocid is the docid of the new row.
*/
static int fts3InsertTerms(Fts3Table *p, sqlite3_value **apVal){
int i; /* Iterator variable */
for(i=2; i<p->nColumn+2; i++){
const char *zText = (const char *)sqlite3_value_text(apVal[i]);
if( zText ){
int rc = fts3PendingTermsAdd(p, zText, i-2);
if( rc!=SQLITE_OK ){
return rc;
}
}
}
return SQLITE_OK;
}
/*
** This function is called by the xUpdate() method for an INSERT operation.
** The apVal parameter is passed a copy of the apVal argument passed by
** SQLite to the xUpdate() method. i.e:
**
** apVal[0] Not used for INSERT.
** apVal[1] rowid
** apVal[2] Left-most user-defined column
** ...
** apVal[p->nColumn+1] Right-most user-defined column
** apVal[p->nColumn+2] Hidden column with same name as table
** apVal[p->nColumn+3] Hidden "docid" column (alias for rowid)
*/
static int fts3InsertData(
Fts3Table *p, /* Full-text table */
sqlite3_value **apVal, /* Array of values to insert */
sqlite3_int64 *piDocid /* OUT: Docid for row just inserted */
){
int rc; /* Return code */
int i; /* Iterator variable */
sqlite3_stmt *pContentInsert; /* INSERT INTO %_content VALUES(...) */
/* Locate the statement handle used to insert data into the %_content
** table. The SQL for this statement is:
**
** INSERT INTO %_content VALUES(?, ?, ?, ...)
**
** The statement features N '?' variables, where N is the number of user
** defined columns in the FTS3 table, plus one for the docid field.
*/
rc = fts3SqlStmt(p, SQL_CONTENT_INSERT, &pContentInsert, &apVal[1]);
if( rc!=SQLITE_OK ){
return rc;
}
/* There is a quirk here. The users INSERT statement may have specified
** a value for the "rowid" field, for the "docid" field, or for both.
** Which is a problem, since "rowid" and "docid" are aliases for the
** same value. For example:
**
** INSERT INTO fts3tbl(rowid, docid) VALUES(1, 2);
**
** In FTS3, if a non-NULL docid value is specified, it is the value
** inserted. Otherwise, the rowid value is used.
*/
if( SQLITE_NULL!=sqlite3_value_type(apVal[3+p->nColumn]) ){
rc = sqlite3_bind_value(pContentInsert, 1, apVal[3+p->nColumn]);
if( rc!=SQLITE_OK ) return rc;
}
/* Execute the statement to insert the record. Set *piDocid to the
** new docid value.
*/
sqlite3_step(pContentInsert);
rc = sqlite3_reset(pContentInsert);
*piDocid = sqlite3_last_insert_rowid(p->db);
return rc;
}
/*
** Remove all data from the FTS3 table. Clear the hash table containing
** pending terms.
*/
static int fts3DeleteAll(Fts3Table *p){
int rc; /* Return code */
/* Discard the contents of the pending-terms hash table. */
sqlite3Fts3PendingTermsClear(p);
/* Delete everything from the %_content, %_segments and %_segdir tables. */
rc = fts3SqlExec(p, SQL_DELETE_ALL_CONTENT, 0);
if( rc==SQLITE_OK ){
rc = fts3SqlExec(p, SQL_DELETE_ALL_SEGMENTS, 0);
}
if( rc==SQLITE_OK ){
rc = fts3SqlExec(p, SQL_DELETE_ALL_SEGDIR, 0);
}
return rc;
}
/*
** The first element in the apVal[] array is assumed to contain the docid
** (an integer) of a row about to be deleted. Remove all terms from the
** full-text index.
*/
static int fts3DeleteTerms(Fts3Table *p, sqlite3_value **apVal){
int rc;
sqlite3_stmt *pSelect;
rc = fts3SqlStmt(p, SQL_SELECT_CONTENT_BY_ROWID, &pSelect, apVal);
if( rc==SQLITE_OK ){
if( SQLITE_ROW==sqlite3_step(pSelect) ){
int i;
for(i=1; i<=p->nColumn; i++){
const char *zText = (const char *)sqlite3_column_text(pSelect, i);
rc = fts3PendingTermsAdd(p, zText, -1);
if( rc!=SQLITE_OK ){
sqlite3_reset(pSelect);
return rc;
}
}
}
rc = sqlite3_reset(pSelect);
}else{
sqlite3_reset(pSelect);
}
return rc;
}
/*
** Forward declaration to account for the circular dependency between
** functions fts3SegmentMerge() and fts3AllocateSegdirIdx().
*/
static int fts3SegmentMerge(Fts3Table *, int);
/*
** This function allocates a new level iLevel index in the segdir table.
** Usually, indexes are allocated within a level sequentially starting
** with 0, so the allocated index is one greater than the value returned
** by:
**
** SELECT max(idx) FROM %_segdir WHERE level = :iLevel
**
** However, if there are already FTS3_MERGE_COUNT indexes at the requested
** level, they are merged into a single level (iLevel+1) segment and the
** allocated index is 0.
**
** If successful, *piIdx is set to the allocated index slot and SQLITE_OK
** returned. Otherwise, an SQLite error code is returned.
*/
static int fts3AllocateSegdirIdx(Fts3Table *p, int iLevel, int *piIdx){
int rc; /* Return Code */
sqlite3_stmt *pNextIdx; /* Query for next idx at level iLevel */
int iNext; /* Result of query pNextIdx */
/* Set variable iNext to the next available segdir index at level iLevel. */
rc = fts3SqlStmt(p, SQL_NEXT_SEGMENT_INDEX, &pNextIdx, 0);
if( rc==SQLITE_OK ){
sqlite3_bind_int(pNextIdx, 1, iLevel);
if( SQLITE_ROW==sqlite3_step(pNextIdx) ){
iNext = sqlite3_column_int64(pNextIdx, 0);
}
rc = sqlite3_reset(pNextIdx);
}
if( rc==SQLITE_OK ){
/* If iNext is FTS3_MERGE_COUNT, indicating that level iLevel is already
** full, merge all segments in level iLevel into a single iLevel+1
** segment and allocate (newly freed) index 0 at level iLevel. Otherwise,
** if iNext is less than FTS3_MERGE_COUNT, allocate index iNext.
*/
if( iNext>=FTS3_MERGE_COUNT ){
rc = fts3SegmentMerge(p, iLevel);
*piIdx = 0;
}else{
*piIdx = iNext;
}
}
return rc;
}
/*
** Move the iterator passed as the first argument to the next term in the
** segment. If successful, SQLITE_OK is returned. If there is no next term,
** SQLITE_DONE. Otherwise, an SQLite error code.
*/
static int fts3SegReaderNext(Fts3SegReader *pReader){
char *pNext; /* Cursor variable */
int nPrefix; /* Number of bytes in term prefix */
int nSuffix; /* Number of bytes in term suffix */
if( !pReader->aDoclist ){
pNext = pReader->aNode;
}else{
pNext = &pReader->aDoclist[pReader->nDoclist];
}
if( !pNext || pNext>=&pReader->aNode[pReader->nNode] ){
int rc;
if( !pReader->pStmt ){
pReader->aNode = 0;
return SQLITE_OK;
}
rc = sqlite3_step(pReader->pStmt);
if( rc!=SQLITE_ROW ){
pReader->aNode = 0;
return (rc==SQLITE_DONE ? SQLITE_OK : rc);
}
pReader->nNode = sqlite3_column_bytes(pReader->pStmt, 0);
pReader->aNode = (char *)sqlite3_column_blob(pReader->pStmt, 0);
pNext = pReader->aNode;
}
pNext += sqlite3Fts3GetVarint32(pNext, &nPrefix);
pNext += sqlite3Fts3GetVarint32(pNext, &nSuffix);
if( nPrefix+nSuffix>pReader->nTermAlloc ){
int nNew = (nPrefix+nSuffix)*2;
char *zNew = sqlite3_realloc(pReader->zTerm, nNew);
if( !zNew ){
return SQLITE_NOMEM;
}
pReader->zTerm = zNew;
pReader->nTermAlloc = nNew;
}
memcpy(&pReader->zTerm[nPrefix], pNext, nSuffix);
pReader->nTerm = nPrefix+nSuffix;
pNext += nSuffix;
pNext += sqlite3Fts3GetVarint32(pNext, &pReader->nDoclist);
assert( pNext<&pReader->aNode[pReader->nNode] );
pReader->aDoclist = pNext;
pReader->pOffsetList = 0;
return SQLITE_OK;
}
/*
** Set the SegReader to point to the first docid in the doclist associated
** with the current term.
*/
static void fts3SegReaderFirstDocid(Fts3SegReader *pReader){
int n;
assert( pReader->aDoclist );
assert( !pReader->pOffsetList );
n = sqlite3Fts3GetVarint(pReader->aDoclist, &pReader->iDocid);
pReader->pOffsetList = &pReader->aDoclist[n];
}
/*
** Advance the SegReader to point to the next docid in the doclist
** associated with the current term.
**
** If arguments ppOffsetList and pnOffsetList are not NULL, then
** *ppOffsetList is set to point to the first column-offset list
** in the doclist entry (i.e. immediately past the docid varint).
** *pnOffsetList is set to the length of the set of column-offset
** lists, not including the nul-terminator byte. For example:
*/
static void fts3SegReaderNextDocid(
Fts3SegReader *pReader,
char **ppOffsetList,
int *pnOffsetList
){
char *p = pReader->pOffsetList;
char c = 0;
/* Pointer p currently points at the first byte of an offset list. The
** following two lines advance it to point one byte past the end of
** the same offset list.
*/
while( *p | c ) c = *p++ & 0x80;
p++;
/* If required, populate the output variables with a pointer to and the
** size of the previous offset-list.
*/
if( ppOffsetList ){
*ppOffsetList = pReader->pOffsetList;
*pnOffsetList = p - pReader->pOffsetList - 1;
}
/* If there are no more entries in the doclist, set pOffsetList to
** NULL. Otherwise, set Fts3SegReader.iDocid to the next docid and
** Fts3SegReader.pOffsetList to point to the next offset list before
** returning.
*/
if( p>=&pReader->aDoclist[pReader->nDoclist] ){
pReader->pOffsetList = 0;
}else{
sqlite3_int64 iDelta;
pReader->pOffsetList = p + sqlite3Fts3GetVarint(p, &iDelta);
pReader->iDocid += iDelta;
}
}
/*
** Free all allocations associated with the iterator passed as the
** second argument.
*/
void sqlite3Fts3SegReaderFree(Fts3Table *p, Fts3SegReader *pReader){
if( pReader ){
if( pReader->pStmt ){
/* Move the leaf-range SELECT statement to the aLeavesStmt[] array,
** so that it can be reused when required by another query.
*/
assert( p->nLeavesStmt<p->nLeavesTotal );
sqlite3_reset(pReader->pStmt);
p->aLeavesStmt[p->nLeavesStmt++] = pReader->pStmt;
}
sqlite3_free(pReader->zTerm);
sqlite3_free(pReader);
}
}
/*
** Allocate a new SegReader object.
*/
int sqlite3Fts3SegReaderNew(
Fts3Table *p, /* Virtual table handle */
int iAge, /* Segment "age". */
sqlite3_int64 iStartLeaf, /* First leaf to traverse */
sqlite3_int64 iEndLeaf, /* Final leaf to traverse */
sqlite3_int64 iEndBlock, /* Final block of segment */
const char *zRoot, /* Buffer containing root node */
int nRoot, /* Size of buffer containing root node */
Fts3SegReader **ppReader /* OUT: Allocated Fts3SegReader */
){
int rc = SQLITE_OK; /* Return code */
Fts3SegReader *pReader; /* Newly allocated SegReader object */
int nExtra = 0; /* Bytes to allocate segment root node */
if( iStartLeaf==0 ){
nExtra = nRoot;
}
pReader = (Fts3SegReader *)sqlite3_malloc(sizeof(Fts3SegReader) + nExtra);
if( !pReader ){
return SQLITE_NOMEM;
}
memset(pReader, 0, sizeof(Fts3SegReader));
pReader->iStartBlock = iStartLeaf;
pReader->iIdx = iAge;
pReader->iEndBlock = iEndBlock;
if( nExtra ){
/* The entire segment is stored in the root node. */
pReader->aNode = (char *)&pReader[1];
pReader->nNode = nRoot;
memcpy(pReader->aNode, zRoot, nRoot);
}else{
sqlite3_stmt *pStmt;
/* If the text of the SQL statement to iterate through a contiguous
** set of entries in the %_segments table has not yet been composed,
** compose it now.
*/
if( !p->zSelectLeaves ){
p->zSelectLeaves = sqlite3_mprintf(
"SELECT block FROM %Q.'%q_segments' WHERE blockid BETWEEN ? AND ? "
"ORDER BY blockid", p->zDb, p->zName
);
if( !p->zSelectLeaves ){
rc = SQLITE_NOMEM;
goto finished;
}
}
/* If there are no free statements in the aLeavesStmt[] array, prepare
** a new statement now. Otherwise, reuse a prepared statement from
** aLeavesStmt[].
*/
if( p->nLeavesStmt==0 ){
if( p->nLeavesTotal==p->nLeavesAlloc ){
int nNew = p->nLeavesAlloc + 16;
sqlite3_stmt **aNew = (sqlite3_stmt **)sqlite3_realloc(
p->aLeavesStmt, nNew*sizeof(sqlite3_stmt *)
);
if( !aNew ){
rc = SQLITE_NOMEM;
goto finished;
}
p->nLeavesAlloc = nNew;
p->aLeavesStmt = aNew;
}
rc = sqlite3_prepare_v2(p->db, p->zSelectLeaves, -1, &pReader->pStmt, 0);
if( rc!=SQLITE_OK ){
goto finished;
}
p->nLeavesTotal++;
}else{
pReader->pStmt = p->aLeavesStmt[--p->nLeavesStmt];
}
/* Bind the start and end leaf blockids to the prepared SQL statement. */
sqlite3_bind_int64(pReader->pStmt, 1, iStartLeaf);
sqlite3_bind_int64(pReader->pStmt, 2, iEndLeaf);
}
rc = fts3SegReaderNext(pReader);
finished:
if( rc==SQLITE_OK ){
*ppReader = pReader;
}else{
sqlite3Fts3SegReaderFree(p, pReader);
}
return rc;
}
/*
** The second argument to this function is expected to be a statement of
** the form:
**
** SELECT
** idx, -- col 0
** start_block, -- col 1
** leaves_end_block, -- col 2
** end_block, -- col 3
** root -- col 4
** FROM %_segdir ...
**
** This function allocates and initializes a Fts3SegReader structure to
** iterate through the terms stored in the segment identified by the
** current row that pStmt is pointing to.
**
** If successful, the Fts3SegReader is left pointing to the first term
** in the segment and SQLITE_OK is returned. Otherwise, an SQLite error
** code is returned.
*/
static int fts3SegReaderNew(
Fts3Table *p, /* Virtual table handle */
sqlite3_stmt *pStmt, /* See above */
int iAge, /* Segment "age". */
Fts3SegReader **ppReader /* OUT: Allocated Fts3SegReader */
){
return sqlite3Fts3SegReaderNew(p, iAge,
sqlite3_column_int64(pStmt, 1),
sqlite3_column_int64(pStmt, 2),
sqlite3_column_int64(pStmt, 3),
sqlite3_column_blob(pStmt, 4),
sqlite3_column_bytes(pStmt, 4),
ppReader
);
}
/*
** Compare the entries pointed to by two Fts3SegReader structures.
** Comparison is as follows:
**
** 1) EOF is greater than not EOF.
**
** 2) The current terms (if any) are compared with memcmp(). If one
** term is a prefix of another, the longer term is considered the
** larger.
**
** 3) By segment age. An older segment is considered larger.
*/
static int fts3SegReaderCmp(Fts3SegReader *pLhs, Fts3SegReader *pRhs){
int rc;
if( pLhs->aNode && pRhs->aNode ){
int rc2 = pLhs->nTerm - pRhs->nTerm;
if( rc2<0 ){
rc = memcmp(pLhs->zTerm, pRhs->zTerm, pLhs->nTerm);
}else{
rc = memcmp(pLhs->zTerm, pRhs->zTerm, pRhs->nTerm);
}
if( rc==0 ){
rc = rc2;
}
}else{
rc = (pLhs->aNode==0) - (pRhs->aNode==0);
}
if( rc==0 ){
rc = pRhs->iIdx - pLhs->iIdx;
}
assert( rc!=0 );
return rc;
}
/*
** A different comparison function for SegReader structures. In this
** version, it is assumed that each SegReader points to an entry in
** a doclist for identical terms. Comparison is made as follows:
**
** 1) EOF (end of doclist in this case) is greater than not EOF.
**
** 2) By current docid.
**
** 3) By segment age. An older segment is considered larger.
*/
static int fts3SegReaderDoclistCmp(Fts3SegReader *pLhs, Fts3SegReader *pRhs){
int rc = (pLhs->pOffsetList==0)-(pRhs->pOffsetList==0);
if( rc==0 ){
if( pLhs->iDocid==pRhs->iDocid ){
rc = pRhs->iIdx - pLhs->iIdx;
}else{
rc = (pLhs->iDocid > pRhs->iDocid) ? 1 : -1;
}
}
assert( pLhs->aNode && pRhs->aNode );
return rc;
}
/*
** Compare the term that the Fts3SegReader object passed as the first argument
** points to with the term specified by arguments zTerm and nTerm.
**
** If the pSeg iterator is already at EOF, return 0. Otherwise, return
** -ve if the pSeg term is less than zTerm/nTerm, 0 if the two terms are
** equal, or +ve if the pSeg term is greater than zTerm/nTerm.
*/
static int fts3SegReaderTermCmp(
Fts3SegReader *pSeg, /* Segment reader object */
const char *zTerm, /* Term to compare to */
int nTerm /* Size of term zTerm in bytes */
){
int res = 0;
if( pSeg->aNode ){
if( pSeg->nTerm>nTerm ){
res = memcmp(pSeg->zTerm, zTerm, nTerm);
}else{
res = memcmp(pSeg->zTerm, zTerm, pSeg->nTerm);
}
if( res==0 ){
res = pSeg->nTerm-nTerm;
}
}
return res;
}
/*
** Argument apSegment is an array of nSegment elements. It is known that
** the final (nSegment-nSuspect) members are already in sorted order
** (according to the comparison function provided). This function shuffles
** the array around until all entries are in sorted order.
*/
static void fts3SegReaderSort(
Fts3SegReader **apSegment, /* Array to sort entries of */
int nSegment, /* Size of apSegment array */
int nSuspect, /* Unsorted entry count */
int (*xCmp)(Fts3SegReader *, Fts3SegReader *) /* Comparison function */
){
int i; /* Iterator variable */
assert( nSuspect<=nSegment );
if( nSuspect==nSegment ) nSuspect--;
for(i=nSuspect-1; i>=0; i--){
int j;
for(j=i; j<(nSegment-1); j++){
Fts3SegReader *pTmp;
if( xCmp(apSegment[j], apSegment[j+1])<0 ) break;
pTmp = apSegment[j+1];
apSegment[j+1] = apSegment[j];
apSegment[j] = pTmp;
}
}
#ifndef NDEBUG
/* Check that the list really is sorted now. */
for(i=0; i<(nSuspect-1); i++){
assert( xCmp(apSegment[i], apSegment[i+1])<0 );
}
#endif
}
/*
** Insert a record into the %_segments table.
*/
static int fts3WriteSegment(
Fts3Table *p, /* Virtual table handle */
sqlite3_int64 iBlock, /* Block id for new block */
char *z, /* Pointer to buffer containing block data */
int n /* Size of buffer z in bytes */
){
sqlite3_stmt *pStmt;
int rc = fts3SqlStmt(p, SQL_INSERT_SEGMENTS, &pStmt, 0);
if( rc==SQLITE_OK ){
sqlite3_bind_int64(pStmt, 1, iBlock);
rc = sqlite3_bind_blob(pStmt, 2, z, n, SQLITE_STATIC);
if( rc==SQLITE_OK ){
sqlite3_step(pStmt);
rc = sqlite3_reset(pStmt);
}
}
return rc;
}
/*
** Insert a record into the %_segdir table.
*/
static int fts3WriteSegdir(
Fts3Table *p, /* Virtual table handle */
int iLevel, /* Value for "level" field */
int iIdx, /* Value for "idx" field */
sqlite3_int64 iStartBlock, /* Value for "start_block" field */
sqlite3_int64 iLeafEndBlock, /* Value for "leaves_end_block" field */
sqlite3_int64 iEndBlock, /* Value for "end_block" field */
char *zRoot, /* Blob value for "root" field */
int nRoot /* Number of bytes in buffer zRoot */
){
sqlite3_stmt *pStmt;
int rc = fts3SqlStmt(p, SQL_INSERT_SEGDIR, &pStmt, 0);
if( rc==SQLITE_OK ){
sqlite3_bind_int(pStmt, 1, iLevel);
sqlite3_bind_int(pStmt, 2, iIdx);
sqlite3_bind_int64(pStmt, 3, iStartBlock);
sqlite3_bind_int64(pStmt, 4, iLeafEndBlock);
sqlite3_bind_int64(pStmt, 5, iEndBlock);
rc = sqlite3_bind_blob(pStmt, 6, zRoot, nRoot, SQLITE_STATIC);
if( rc==SQLITE_OK ){
sqlite3_step(pStmt);
rc = sqlite3_reset(pStmt);
}
}
return rc;
}
/*
** Return the size of the common prefix (if any) shared by zPrev and
** zNext, in bytes. For example,
**
** fts3PrefixCompress("abc", 3, "abcdef", 6) // returns 3
** fts3PrefixCompress("abX", 3, "abcdef", 6) // returns 2
** fts3PrefixCompress("abX", 3, "Xbcdef", 6) // returns 0
*/
static int fts3PrefixCompress(
const char *zPrev, /* Buffer containing previous term */
int nPrev, /* Size of buffer zPrev in bytes */
const char *zNext, /* Buffer containing next term */
int nNext /* Size of buffer zNext in bytes */
){
int n;
for(n=0; n<nPrev && zPrev[n]==zNext[n]; n++);
return n;
}
/*
** Add term zTerm to the SegmentNode. It is guaranteed that zTerm is larger
** (according to memcmp) than the previous term.
*/
static int fts3NodeAddTerm(
Fts3Table *p, /* Virtual table handle */
SegmentNode **ppTree, /* IN/OUT: SegmentNode handle */
int isCopyTerm, /* True if zTerm/nTerm is transient */
const char *zTerm, /* Pointer to buffer containing term */
int nTerm /* Size of term in bytes */
){
SegmentNode *pTree = *ppTree;
int rc;
SegmentNode *pNew;
/* First try to append the term to the current node. Return early if
** this is possible.
*/
if( pTree ){
int nData = pTree->nData; /* Current size of node in bytes */
int nReq = nData; /* Required space after adding zTerm */
int nPrefix; /* Number of bytes of prefix compression */
int nSuffix; /* Suffix length */
nPrefix = fts3PrefixCompress(pTree->zTerm, pTree->nTerm, zTerm, nTerm);
nSuffix = nTerm-nPrefix;
nReq += sqlite3Fts3VarintLen(nPrefix)+sqlite3Fts3VarintLen(nSuffix)+nSuffix;
if( nReq<=INTERIOR_MAX || !pTree->zTerm ){
if( nReq>INTERIOR_MAX ){
/* An unusual case: this is the first term to be added to the node
** and the static node buffer (INTERIOR_MAX bytes) is not large
** enough. Use a separately malloced buffer instead This wastes
** INTERIOR_MAX bytes, but since this scenario only comes about when
** the database contain two terms that share a prefix of almost 2KB,
** this is not expected to be a serious problem.
*/
assert( pTree->aData==(char *)&pTree[1] );
pTree->aData = (char *)sqlite3_malloc(nReq);
if( !pTree->aData ){
return SQLITE_NOMEM;
}
}
if( pTree->zTerm ){
/* There is no prefix-length field for first term in a node */
nData += sqlite3Fts3PutVarint(&pTree->aData[nData], nPrefix);
}
nData += sqlite3Fts3PutVarint(&pTree->aData[nData], nSuffix);
memcpy(&pTree->aData[nData], &zTerm[nPrefix], nSuffix);
pTree->nData = nData + nSuffix;
pTree->nEntry++;
if( isCopyTerm ){
if( pTree->nMalloc<nTerm ){
char *zNew = sqlite3_realloc(pTree->zMalloc, nTerm*2);
if( !zNew ){
return SQLITE_NOMEM;
}
pTree->nMalloc = nTerm*2;
pTree->zMalloc = zNew;
}
pTree->zTerm = pTree->zMalloc;
memcpy(pTree->zTerm, zTerm, nTerm);
pTree->nTerm = nTerm;
}else{
pTree->zTerm = (char *)zTerm;
pTree->nTerm = nTerm;
}
return SQLITE_OK;
}
}
/* If control flows to here, it was not possible to append zTerm to the
** current node. Create a new node (a right-sibling of the current node).
** If this is the first node in the tree, the term is added to it.
**
** Otherwise, the term is not added to the new node, it is left empty for
** now. Instead, the term is inserted into the parent of pTree. If pTree
** has no parent, one is created here.
*/
pNew = (SegmentNode *)sqlite3_malloc(sizeof(SegmentNode) + INTERIOR_MAX);
if( !pNew ){
return SQLITE_NOMEM;
}
memset(pNew, 0, sizeof(SegmentNode));
pNew->nData = 1 + FTS3_VARINT_MAX;
pNew->aData = (char *)&pNew[1];
if( pTree ){
SegmentNode *pParent = pTree->pParent;
rc = fts3NodeAddTerm(p, &pParent, isCopyTerm, zTerm, nTerm);
if( pTree->pParent==0 ){
pTree->pParent = pParent;
}
pTree->pRight = pNew;
pNew->pLeftmost = pTree->pLeftmost;
pNew->pParent = pParent;
pNew->zMalloc = pTree->zMalloc;
pNew->nMalloc = pTree->nMalloc;
pTree->zMalloc = 0;
}else{
pNew->pLeftmost = pNew;
rc = fts3NodeAddTerm(p, &pNew, isCopyTerm, zTerm, nTerm);
}
*ppTree = pNew;
return rc;
}
/*
** Helper function for fts3NodeWrite().
*/
static int fts3TreeFinishNode(
SegmentNode *pTree,
int iHeight,
sqlite3_int64 iLeftChild
){
int nStart;
assert( iHeight>=1 && iHeight<128 );
nStart = FTS3_VARINT_MAX - sqlite3Fts3VarintLen(iLeftChild);
pTree->aData[nStart] = (char)iHeight;
sqlite3Fts3PutVarint(&pTree->aData[nStart+1], iLeftChild);
return nStart;
}
/*
** Write the buffer for the segment node pTree and all of its peers to the
** database. Then call this function recursively to write the parent of
** pTree and its peers to the database.
**
** Except, if pTree is a root node, do not write it to the database. Instead,
** set output variables *paRoot and *pnRoot to contain the root node.
**
** If successful, SQLITE_OK is returned and output variable *piLast is
** set to the largest blockid written to the database (or zero if no
** blocks were written to the db). Otherwise, an SQLite error code is
** returned.
*/
static int fts3NodeWrite(
Fts3Table *p, /* Virtual table handle */
SegmentNode *pTree, /* SegmentNode handle */
int iHeight, /* Height of this node in tree */
sqlite3_int64 iLeaf, /* Block id of first leaf node */
sqlite3_int64 iFree, /* Block id of next free slot in %_segments */
sqlite3_int64 *piLast, /* OUT: Block id of last entry written */
char **paRoot, /* OUT: Data for root node */
int *pnRoot /* OUT: Size of root node in bytes */
){
int rc = SQLITE_OK;
if( !pTree->pParent ){
/* Root node of the tree. */
int nStart = fts3TreeFinishNode(pTree, iHeight, iLeaf);
*piLast = iFree-1;
*pnRoot = pTree->nData - nStart;
*paRoot = &pTree->aData[nStart];
}else{
SegmentNode *pIter;
sqlite3_int64 iNextFree = iFree;
sqlite3_int64 iNextLeaf = iLeaf;
for(pIter=pTree->pLeftmost; pIter && rc==SQLITE_OK; pIter=pIter->pRight){
int nStart = fts3TreeFinishNode(pIter, iHeight, iNextLeaf);
int nWrite = pIter->nData - nStart;
rc = fts3WriteSegment(p, iNextFree, &pIter->aData[nStart], nWrite);
iNextFree++;
iNextLeaf += (pIter->nEntry+1);
}
if( rc==SQLITE_OK ){
assert( iNextLeaf==iFree );
rc = fts3NodeWrite(
p, pTree->pParent, iHeight+1, iFree, iNextFree, piLast, paRoot, pnRoot
);
}
}
return rc;
}
/*
** Free all memory allocations associated with the tree pTree.
*/
static void fts3NodeFree(SegmentNode *pTree){
if( pTree ){
SegmentNode *p = pTree->pLeftmost;
fts3NodeFree(p->pParent);
while( p ){
SegmentNode *pRight = p->pRight;
if( p->aData!=(char *)&p[1] ){
sqlite3_free(p->aData);
}
assert( pRight==0 || p->zMalloc==0 );
sqlite3_free(p->zMalloc);
sqlite3_free(p);
p = pRight;
}
}
}
/*
** Add a term to the segment being constructed by the SegmentWriter object
** *ppWriter. When adding the first term to a segment, *ppWriter should
** be passed NULL. This function will allocate a new SegmentWriter object
** and return it via the input/output variable *ppWriter in this case.
**
** If successful, SQLITE_OK is returned. Otherwise, an SQLite error code.
*/
static int fts3SegWriterAdd(
Fts3Table *p, /* Virtual table handle */
SegmentWriter **ppWriter, /* IN/OUT: SegmentWriter handle */
int isCopyTerm, /* True if buffer zTerm must be copied */
const char *zTerm, /* Pointer to buffer containing term */
int nTerm, /* Size of term in bytes */
const char *aDoclist, /* Pointer to buffer containing doclist */
int nDoclist /* Size of doclist in bytes */
){
int nPrefix; /* Size of term prefix in bytes */
int nSuffix; /* Size of term suffix in bytes */
int nReq; /* Number of bytes required on leaf page */
int nData;
SegmentWriter *pWriter = *ppWriter;
if( !pWriter ){
int rc;
sqlite3_stmt *pStmt;
/* Allocate the SegmentWriter structure */
pWriter = (SegmentWriter *)sqlite3_malloc(sizeof(SegmentWriter));
if( !pWriter ) return SQLITE_NOMEM;
memset(pWriter, 0, sizeof(SegmentWriter));
*ppWriter = pWriter;
/* Allocate a buffer in which to accumulate data */
pWriter->aData = (char *)sqlite3_malloc(LEAF_MAX);
if( !pWriter->aData ) return SQLITE_NOMEM;
pWriter->nSize = LEAF_MAX;
/* Find the next free blockid in the %_segments table */
rc = fts3SqlStmt(p, SQL_NEXT_SEGMENTS_ID, &pStmt, 0);
if( rc!=SQLITE_OK ) return rc;
if( SQLITE_ROW==sqlite3_step(pStmt) ){
pWriter->iFree = sqlite3_column_int64(pStmt, 0);
pWriter->iFirst = pWriter->iFree;
}
rc = sqlite3_reset(pStmt);
if( rc!=SQLITE_OK ) return rc;
}
nData = pWriter->nData;
nPrefix = fts3PrefixCompress(pWriter->zTerm, pWriter->nTerm, zTerm, nTerm);
nSuffix = nTerm-nPrefix;
/* Figure out how many bytes are required by this new entry */
nReq = sqlite3Fts3VarintLen(nPrefix) + /* varint containing prefix size */
sqlite3Fts3VarintLen(nSuffix) + /* varint containing suffix size */
nSuffix + /* Term suffix */
sqlite3Fts3VarintLen(nDoclist) + /* Size of doclist */
nDoclist; /* Doclist data */
if( nData>0 && nData+nReq>LEAF_MAX ){
int rc;
/* The current leaf node is full. Write it out to the database. */
rc = fts3WriteSegment(p, pWriter->iFree++, pWriter->aData, nData);
if( rc!=SQLITE_OK ) return rc;
/* Add the current term to the interior node tree. The term added to
** the interior tree must:
**
** a) be greater than the largest term on the leaf node just written
** to the database (still available in pWriter->zTerm), and
**
** b) be less than or equal to the term about to be added to the new
** leaf node (zTerm/nTerm).
**
** In other words, it must be the prefix of zTerm 1 byte longer than
** the common prefix (if any) of zTerm and pWriter->zTerm.
*/
assert( nPrefix<nTerm );
rc = fts3NodeAddTerm(p, &pWriter->pTree, isCopyTerm, zTerm, nPrefix+1);
if( rc!=SQLITE_OK ) return rc;
nData = 0;
pWriter->nTerm = 0;
nPrefix = 0;
nSuffix = nTerm;
nReq = 1 + /* varint containing prefix size */
sqlite3Fts3VarintLen(nTerm) + /* varint containing suffix size */
nTerm + /* Term suffix */
sqlite3Fts3VarintLen(nDoclist) + /* Size of doclist */
nDoclist; /* Doclist data */
}
/* If the buffer currently allocated is too small for this entry, realloc
** the buffer to make it large enough.
*/
if( nReq>pWriter->nSize ){
char *aNew = sqlite3_realloc(pWriter->aData, nReq);
if( !aNew ) return SQLITE_NOMEM;
pWriter->aData = aNew;
pWriter->nSize = nReq;
}
assert( nData+nReq<=pWriter->nSize );
/* Append the prefix-compressed term and doclist to the buffer. */
nData += sqlite3Fts3PutVarint(&pWriter->aData[nData], nPrefix);
nData += sqlite3Fts3PutVarint(&pWriter->aData[nData], nSuffix);
memcpy(&pWriter->aData[nData], &zTerm[nPrefix], nSuffix);
nData += nSuffix;
nData += sqlite3Fts3PutVarint(&pWriter->aData[nData], nDoclist);
memcpy(&pWriter->aData[nData], aDoclist, nDoclist);
pWriter->nData = nData + nDoclist;
/* Save the current term so that it can be used to prefix-compress the next.
** If the isCopyTerm parameter is true, then the buffer pointed to by
** zTerm is transient, so take a copy of the term data. Otherwise, just
** store a copy of the pointer.
*/
if( isCopyTerm ){
if( nTerm>pWriter->nMalloc ){
char *zNew = sqlite3_realloc(pWriter->zMalloc, nTerm*2);
if( !zNew ){
return SQLITE_NOMEM;
}
pWriter->nMalloc = nTerm*2;
pWriter->zMalloc = zNew;
pWriter->zTerm = zNew;
}
assert( pWriter->zTerm==pWriter->zMalloc );
memcpy(pWriter->zTerm, zTerm, nTerm);
}else{
pWriter->zTerm = (char *)zTerm;
}
pWriter->nTerm = nTerm;
return SQLITE_OK;
}
/*
** Flush all data associated with the SegmentWriter object pWriter to the
** database. This function must be called after all terms have been added
** to the segment using fts3SegWriterAdd(). If successful, SQLITE_OK is
** returned. Otherwise, an SQLite error code.
*/
static int fts3SegWriterFlush(
Fts3Table *p, /* Virtual table handle */
SegmentWriter *pWriter, /* SegmentWriter to flush to the db */
int iLevel, /* Value for 'level' column of %_segdir */
int iIdx /* Value for 'idx' column of %_segdir */
){
int rc; /* Return code */
if( pWriter->pTree ){
sqlite3_int64 iLast; /* Largest block id written to database */
sqlite3_int64 iLastLeaf; /* Largest leaf block id written to db */
char *zRoot; /* Pointer to buffer containing root node */
int nRoot; /* Size of buffer zRoot */
iLastLeaf = pWriter->iFree;
rc = fts3WriteSegment(p, pWriter->iFree++, pWriter->aData, pWriter->nData);
if( rc==SQLITE_OK ){
rc = fts3NodeWrite(p, pWriter->pTree, 1,
pWriter->iFirst, pWriter->iFree, &iLast, &zRoot, &nRoot);
}
if( rc==SQLITE_OK ){
rc = fts3WriteSegdir(
p, iLevel, iIdx, pWriter->iFirst, iLastLeaf, iLast, zRoot, nRoot);
}
}else{
/* The entire tree fits on the root node. Write it to the segdir table. */
rc = fts3WriteSegdir(
p, iLevel, iIdx, 0, 0, 0, pWriter->aData, pWriter->nData);
}
return rc;
}
/*
** Release all memory held by the SegmentWriter object passed as the
** first argument.
*/
static void fts3SegWriterFree(SegmentWriter *pWriter){
if( pWriter ){
sqlite3_free(pWriter->aData);
sqlite3_free(pWriter->zMalloc);
fts3NodeFree(pWriter->pTree);
sqlite3_free(pWriter);
}
}
/*
** The first value in the apVal[] array is assumed to contain an integer.
** This function tests if there exist any documents with docid values that
** are different from that integer. i.e. if deleting the document with docid
** apVal[0] would mean the FTS3 table were empty.
**
** If successful, *pisEmpty is set to true if the table is empty except for
** document apVal[0], or false otherwise, and SQLITE_OK is returned. If an
** error occurs, an SQLite error code is returned.
*/
static int fts3IsEmpty(Fts3Table *p, sqlite3_value **apVal, int *pisEmpty){
sqlite3_stmt *pStmt;
int rc;
rc = fts3SqlStmt(p, SQL_IS_EMPTY, &pStmt, apVal);
if( rc==SQLITE_OK ){
if( SQLITE_ROW==sqlite3_step(pStmt) ){
*pisEmpty = sqlite3_column_int(pStmt, 0);
}
rc = sqlite3_reset(pStmt);
}
return rc;
}
/*
** Set *pnSegment to the number of segments of level iLevel in the database.
**
** Return SQLITE_OK if successful, or an SQLite error code if not.
*/
static int fts3SegmentCount(Fts3Table *p, int iLevel, int *pnSegment){
sqlite3_stmt *pStmt;
int rc;
assert( iLevel>=0 );
rc = fts3SqlStmt(p, SQL_SELECT_LEVEL_COUNT, &pStmt, 0);
if( rc!=SQLITE_OK ) return rc;
sqlite3_bind_int(pStmt, 1, iLevel);
if( SQLITE_ROW==sqlite3_step(pStmt) ){
*pnSegment = sqlite3_column_int(pStmt, 0);
}
return sqlite3_reset(pStmt);
}
/*
** Set *pnSegment to the total number of segments in the database. Set
** *pnMax to the largest segment level in the database (segment levels
** are stored in the 'level' column of the %_segdir table).
**
** Return SQLITE_OK if successful, or an SQLite error code if not.
*/
static int fts3SegmentCountMax(Fts3Table *p, int *pnSegment, int *pnMax){
sqlite3_stmt *pStmt;
int rc;
rc = fts3SqlStmt(p, SQL_SELECT_SEGDIR_COUNT_MAX, &pStmt, 0);
if( rc!=SQLITE_OK ) return rc;
if( SQLITE_ROW==sqlite3_step(pStmt) ){
*pnSegment = sqlite3_column_int(pStmt, 0);
*pnMax = sqlite3_column_int(pStmt, 1);
}
return sqlite3_reset(pStmt);
}
/*
** This function is used after merging multiple segments into a single large
** segment to delete the old, now redundant, segment b-trees. Specifically,
** it:
**
** 1) Deletes all %_segments entries for the segments associated with
** each of the SegReader objects in the array passed as the third
** argument, and
**
** 2) deletes all %_segdir entries with level iLevel, or all %_segdir
** entries regardless of level if (iLevel<0).
**
** SQLITE_OK is returned if successful, otherwise an SQLite error code.
*/
static int fts3DeleteSegdir(
Fts3Table *p, /* Virtual table handle */
int iLevel, /* Level of %_segdir entries to delete */
Fts3SegReader **apSegment, /* Array of SegReader objects */
int nReader /* Size of array apSegment */
){
int rc; /* Return Code */
int i; /* Iterator variable */
sqlite3_stmt *pDelete; /* SQL statement to delete rows */
rc = fts3SqlStmt(p, SQL_DELETE_SEGMENTS_RANGE, &pDelete, 0);
for(i=0; rc==SQLITE_OK && i<nReader; i++){
Fts3SegReader *pSegment = apSegment[i];
if( pSegment->iStartBlock ){
sqlite3_bind_int64(pDelete, 1, pSegment->iStartBlock);
sqlite3_bind_int64(pDelete, 2, pSegment->iEndBlock);
sqlite3_step(pDelete);
rc = sqlite3_reset(pDelete);
}
}
if( rc!=SQLITE_OK ){
return rc;
}
if( iLevel>=0 ){
rc = fts3SqlStmt(p, SQL_DELETE_SEGDIR_BY_LEVEL, &pDelete, 0);
if( rc==SQLITE_OK ){
sqlite3_bind_int(pDelete, 1, iLevel);
sqlite3_step(pDelete);
rc = sqlite3_reset(pDelete);
}
}else{
rc = fts3SqlExec(p, SQL_DELETE_ALL_SEGDIR, 0);
}
return rc;
}
/*
** When this function is called, buffer *ppList (size *pnList bytes) contains
** a position list that may (or may not) feature multiple columns. This
** function adjusts the pointer *ppList and the length *pnList so that they
** identify the subset of the position list that corresponds to column iCol.
**
** If there are no entries in the input position list for column iCol, then
** *pnList is set to zero before returning.
*/
static void fts3ColumnFilter(
int iCol, /* Column to filter on */
char **ppList, /* IN/OUT: Pointer to position list */
int *pnList /* IN/OUT: Size of buffer *ppList in bytes */
){
char *pList = *ppList;
int nList = *pnList;
char *pEnd = &pList[nList];
int iCurrent = 0;
char *p = pList;
assert( iCol>=0 );
while( 1 ){
char c = 0;
while( p<pEnd && (c | *p)&0xFE ) c = *p++ & 0x80;
if( iCol==iCurrent ){
nList = (p - pList);
break;
}
nList -= (p - pList);
pList = p;
if( nList==0 ){
break;
}
p = &pList[1];
p += sqlite3Fts3GetVarint32(p, &iCurrent);
}
*ppList = pList;
*pnList = nList;
}
/*
** sqlite3Fts3SegReaderIterate() callback used when merging multiple
** segments to create a single, larger segment.
*/
static int fts3MergeCallback(
Fts3Table *p,
void *pContext,
char *zTerm,
int nTerm,
char *aDoclist,
int nDoclist
){
SegmentWriter **ppW = (SegmentWriter **)pContext;
return fts3SegWriterAdd(p, ppW, 1, zTerm, nTerm, aDoclist, nDoclist);
}
/*
** This function is used to iterate through a contiguous set of terms
** stored in the full-text index. It merges data contained in one or
** more segments to support this.
**
** The second argument is passed an array of pointers to SegReader objects
** allocated with sqlite3Fts3SegReaderNew(). This function merges the range
** of terms selected by each SegReader. If a single term is present in
** more than one segment, the associated doclists are merged. For each
** term and (possibly merged) doclist in the merged range, the callback
** function xFunc is invoked with its arguments set as follows.
**
** arg 0: Copy of 'p' parameter passed to this function
** arg 1: Copy of 'pContext' parameter passed to this function
** arg 2: Pointer to buffer containing term
** arg 3: Size of arg 2 buffer in bytes
** arg 4: Pointer to buffer containing doclist
** arg 5: Size of arg 2 buffer in bytes
**
** The 4th argument to this function is a pointer to a structure of type
** Fts3SegFilter, defined in fts3Int.h. The contents of this structure
** further restrict the range of terms that callbacks are made for and
** modify the behaviour of this function. See comments above structure
** definition for details.
*/
int sqlite3Fts3SegReaderIterate(
Fts3Table *p, /* Virtual table handle */
Fts3SegReader **apSegment, /* Array of Fts3SegReader objects */
int nSegment, /* Size of apSegment array */
Fts3SegFilter *pFilter, /* Restrictions on range of iteration */
int (*xFunc)(Fts3Table *, void *, char *, int, char *, int), /* Callback */
void *pContext /* Callback context (2nd argument) */
){
int i; /* Iterator variable */
char *aBuffer = 0; /* Buffer to merge doclists in */
int nAlloc = 0; /* Allocated size of aBuffer buffer */
int rc = SQLITE_OK; /* Return code */
int isIgnoreEmpty = (pFilter->flags & FTS3_SEGMENT_IGNORE_EMPTY);
int isRequirePos = (pFilter->flags & FTS3_SEGMENT_REQUIRE_POS);
int isColFilter = (pFilter->flags & FTS3_SEGMENT_COLUMN_FILTER);
int isPrefix = (pFilter->flags & FTS3_SEGMENT_PREFIX);
/* If the Fts3SegFilter defines a specific term (or term prefix) to search
** for, then advance each segment iterator until it points to a term of
** equal or greater value than the specified term. This prevents many
** unnecessary merge/sort operations for the case where single segment
** b-tree leaf nodes contain more than one term.
*/
if( pFilter->zTerm ){
int nTerm = pFilter->nTerm;
const char *zTerm = pFilter->zTerm;
for(i=0; i<nSegment; i++){
Fts3SegReader *pSeg = apSegment[i];
while( fts3SegReaderTermCmp(pSeg, zTerm, nTerm)<0 ){
rc = fts3SegReaderNext(pSeg);
if( rc!=SQLITE_OK ) goto finished;
}
}
}
fts3SegReaderSort(apSegment, nSegment, nSegment, fts3SegReaderCmp);
while( apSegment[0]->aNode ){
int nTerm = apSegment[0]->nTerm;
char *zTerm = apSegment[0]->zTerm;
int nMerge = 1;
/* If this is a prefix-search, and if the term that apSegment[0] points
** to does not share a suffix with pFilter->zTerm/nTerm, then all
** required callbacks have been made. In this case exit early.
**
** Similarly, if this is a search for an exact match, and the first term
** of segment apSegment[0] is not a match, exit early.
*/
if( pFilter->zTerm ){
if( nTerm<pFilter->nTerm
|| (!isPrefix && nTerm>pFilter->nTerm)
|| memcmp(zTerm, pFilter->zTerm, pFilter->nTerm)
){
goto finished;
}
}
while( nMerge<nSegment
&& apSegment[nMerge]->aNode
&& apSegment[nMerge]->nTerm==nTerm
&& 0==memcmp(zTerm, apSegment[nMerge]->zTerm, nTerm)
){
nMerge++;
}
if( nMerge==1 && !isIgnoreEmpty && !isColFilter && isRequirePos ){
Fts3SegReader *p0 = apSegment[0];
rc = xFunc(p, pContext, zTerm, nTerm, p0->aDoclist, p0->nDoclist);
if( rc!=SQLITE_OK ) goto finished;
}else{
int nDoclist = 0; /* Size of doclist */
sqlite3_int64 iPrev = 0; /* Previous docid stored in doclist */
/* The current term of the first nMerge entries in the array
** of Fts3SegReader objects is the same. The doclists must be merged
** and a single term added to the new segment.
*/
for(i=0; i<nMerge; i++){
fts3SegReaderFirstDocid(apSegment[i]);
}
fts3SegReaderSort(apSegment, nMerge, nMerge, fts3SegReaderDoclistCmp);
while( apSegment[0]->pOffsetList ){
int j; /* Number of segments that share a docid */
char *pList;
int nList;
int nByte;
sqlite3_int64 iDocid = apSegment[0]->iDocid;
fts3SegReaderNextDocid(apSegment[0], &pList, &nList);
j = 1;
while( j<nMerge
&& apSegment[j]->pOffsetList
&& apSegment[j]->iDocid==iDocid
){
fts3SegReaderNextDocid(apSegment[j], 0, 0);
j++;
}
if( isColFilter ){
fts3ColumnFilter(pFilter->iCol, &pList, &nList);
}
if( !isIgnoreEmpty || nList>0 ){
nByte = sqlite3Fts3VarintLen(iDocid-iPrev) + (isRequirePos?nList+1:0);
if( nDoclist+nByte>nAlloc ){
char *aNew;
nAlloc = nDoclist+nByte*2;
aNew = sqlite3_realloc(aBuffer, nAlloc);
if( !aNew ){
rc = SQLITE_NOMEM;
goto finished;
}
aBuffer = aNew;
}
nDoclist += sqlite3Fts3PutVarint(&aBuffer[nDoclist], iDocid-iPrev);
iPrev = iDocid;
if( isRequirePos ){
memcpy(&aBuffer[nDoclist], pList, nList);
nDoclist += nList;
aBuffer[nDoclist++] = '\0';
}
}
fts3SegReaderSort(apSegment, nMerge, j, fts3SegReaderDoclistCmp);
}
if( nDoclist>0 ){
rc = xFunc(p, pContext, zTerm, nTerm, aBuffer, nDoclist);
if( rc!=SQLITE_OK ) goto finished;
}
}
/* If there is a term specified to filter on, and this is not a prefix
** search, return now. The callback that corresponds to the required
** term (if such a term exists in the index) has already been made.
*/
if( pFilter->zTerm && !isPrefix ){
goto finished;
}
for(i=0; i<nMerge; i++){
rc = fts3SegReaderNext(apSegment[i]);
if( rc!=SQLITE_OK ) goto finished;
}
fts3SegReaderSort(apSegment, nSegment, nMerge, fts3SegReaderCmp);
}
finished:
sqlite3_free(aBuffer);
return rc;
}
/*
** Merge all level iLevel segments in the database into a single
** iLevel+1 segment. Or, if iLevel<0, merge all segments into a
** single segment with a level equal to the numerically largest level
** currently present in the database.
**
** If this function is called with iLevel<0, but there is only one
** segment in the database, SQLITE_DONE is returned immediately.
** Otherwise, if successful, SQLITE_OK is returned. If an error occurs,
** an SQLite error code is returned.
*/
static int fts3SegmentMerge(Fts3Table *p, int iLevel){
int i; /* Iterator variable */
int rc; /* Return code */
int iIdx; /* Index of new segment */
int iNewLevel; /* Level to create new segment at */
sqlite3_stmt *pStmt;
SegmentWriter *pWriter = 0;
int nSegment = 0; /* Number of segments being merged */
Fts3SegReader **apSegment = 0; /* Array of Segment iterators */
Fts3SegFilter filter; /* Segment term filter condition */
if( iLevel<0 ){
/* This call is to merge all segments in the database to a single
** segment. The level of the new segment is equal to the the numerically
** greatest segment level currently present in the database. The index
** of the new segment is always 0.
*/
iIdx = 0;
rc = fts3SegmentCountMax(p, &nSegment, &iNewLevel);
if( nSegment==1 ){
return SQLITE_DONE;
}
}else{
/* This call is to merge all segments at level iLevel. Find the next
** available segment index at level iLevel+1. The call to
** fts3AllocateSegdirIdx() will merge the segments at level iLevel+1 to
** a single iLevel+2 segment if necessary.
*/
iNewLevel = iLevel+1;
rc = fts3AllocateSegdirIdx(p, iNewLevel, &iIdx);
if( rc!=SQLITE_OK ) return rc;
rc = fts3SegmentCount(p, iLevel, &nSegment);
}
if( rc!=SQLITE_OK ) return rc;
assert( nSegment>0 );
assert( iNewLevel>=0 );
/* Allocate space for an array of pointers to segment iterators. */
apSegment = (Fts3SegReader**)sqlite3_malloc(sizeof(Fts3SegReader *)*nSegment);
if( !apSegment ){
return SQLITE_NOMEM;
}
memset(apSegment, 0, sizeof(Fts3SegReader *)*nSegment);
/* Allocate a Fts3SegReader structure for each segment being merged. A
** Fts3SegReader stores the state data required to iterate through all
** entries on all leaves of a single segment.
*/
assert( SQL_SELECT_LEVEL+1==SQL_SELECT_ALL_LEVEL);
rc = fts3SqlStmt(p, SQL_SELECT_LEVEL+(iLevel<0), &pStmt, 0);
if( rc!=SQLITE_OK ) goto finished;
sqlite3_bind_int(pStmt, 1, iLevel);
for(i=0; SQLITE_ROW==(sqlite3_step(pStmt)); i++){
rc = fts3SegReaderNew(p, pStmt, i, &apSegment[i]);
if( rc!=SQLITE_OK ){
goto finished;
}
}
rc = sqlite3_reset(pStmt);
pStmt = 0;
if( rc!=SQLITE_OK ) goto finished;
memset(&filter, 0, sizeof(Fts3SegFilter));
filter.flags = FTS3_SEGMENT_REQUIRE_POS;
filter.flags |= (iLevel<0 ? FTS3_SEGMENT_IGNORE_EMPTY : 0);
rc = sqlite3Fts3SegReaderIterate(p, apSegment, nSegment,
&filter, fts3MergeCallback, (void *)&pWriter
);
if( rc!=SQLITE_OK ) goto finished;
rc = fts3DeleteSegdir(p, iLevel, apSegment, nSegment);
if( rc==SQLITE_OK ){
rc = fts3SegWriterFlush(p, pWriter, iNewLevel, iIdx);
}
finished:
fts3SegWriterFree(pWriter);
if( apSegment ){
for(i=0; i<nSegment; i++){
sqlite3Fts3SegReaderFree(p, apSegment[i]);
}
sqlite3_free(apSegment);
}
sqlite3_reset(pStmt);
return rc;
}
/*
** This is a comparison function used as a qsort() callback when sorting
** an array of pending terms by term. This occurs as part of flushing
** the contents of the pending-terms hash table to the database.
*/
static int qsortCompare(const void *lhs, const void *rhs){
char *z1 = fts3HashKey(*(Fts3HashElem **)lhs);
char *z2 = fts3HashKey(*(Fts3HashElem **)rhs);
int n1 = fts3HashKeysize(*(Fts3HashElem **)lhs);
int n2 = fts3HashKeysize(*(Fts3HashElem **)rhs);
int n = (n1<n2 ? n1 : n2);
int c = memcmp(z1, z2, n);
if( c==0 ){
c = n1 - n2;
}
return c;
}
/*
** Flush the contents of pendingTerms to a level 0 segment.
*/
int sqlite3Fts3PendingTermsFlush(Fts3Table *p){
Fts3HashElem *pElem;
int idx, rc, i;
Fts3HashElem **apElem; /* Array of pointers to hash elements */
int nElem; /* Number of terms in new segment */
SegmentWriter *pWriter = 0; /* Used to write the segment */
/* Find the number of terms that will make up the new segment. If there
** are no terms, return early (do not bother to write an empty segment).
*/
nElem = fts3HashCount(&p->pendingTerms);
if( nElem==0 ){
assert( p->nPendingData==0 );
return SQLITE_OK;
}
/* Determine the next index at level 0, merging as necessary. */
rc = fts3AllocateSegdirIdx(p, 0, &idx);
if( rc!=SQLITE_OK ){
return rc;
}
apElem = sqlite3_malloc(nElem*sizeof(Fts3HashElem *));
if( !apElem ){
return SQLITE_NOMEM;
}
i = 0;
for(pElem=fts3HashFirst(&p->pendingTerms); pElem; pElem=fts3HashNext(pElem)){
apElem[i++] = pElem;
}
assert( i==nElem );
/* TODO(shess) Should we allow user-defined collation sequences,
** here? I think we only need that once we support prefix searches.
** Also, should we be using qsort()?
*/
if( nElem>1 ){
qsort(apElem, nElem, sizeof(Fts3HashElem *), qsortCompare);
}
/* Write the segment tree into the database. */
for(i=0; rc==SQLITE_OK && i<nElem; i++){
const char *z = fts3HashKey(apElem[i]);
int n = fts3HashKeysize(apElem[i]);
PendingList *pList = fts3HashData(apElem[i]);
rc = fts3SegWriterAdd(p, &pWriter, 0, z, n, pList->aData, pList->nData+1);
}
if( rc==SQLITE_OK ){
rc = fts3SegWriterFlush(p, pWriter, 0, idx);
}
/* Free all allocated resources before returning */
fts3SegWriterFree(pWriter);
sqlite3_free(apElem);
sqlite3Fts3PendingTermsClear(p);
return rc;
}
/*
** This function does the work for the xUpdate method of FTS3 virtual
** tables.
*/
int sqlite3Fts3UpdateMethod(
sqlite3_vtab *pVtab, /* FTS3 vtab object */
int nArg, /* Size of argument array */
sqlite3_value **apVal, /* Array of arguments */
sqlite_int64 *pRowid /* OUT: The affected (or effected) rowid */
){
Fts3Table *p = (Fts3Table *)pVtab;
int rc = SQLITE_OK; /* Return Code */
int isRemove = 0; /* True for an UPDATE or DELETE */
sqlite3_int64 iRemove; /* Rowid removed by UPDATE or DELETE */
/* If this is a DELETE or UPDATE operation, remove the old record. */
if( sqlite3_value_type(apVal[0])!=SQLITE_NULL ){
int isEmpty;
rc = fts3IsEmpty(p, apVal, &isEmpty);
if( rc==SQLITE_OK ){
if( isEmpty ){
/* Deleting this row means the whole table is empty. In this case
** delete the contents of all three tables and throw away any
** data in the pendingTerms hash table.
*/
rc = fts3DeleteAll(p);
}else{
isRemove = 1;
iRemove = sqlite3_value_int64(apVal[0]);
rc = fts3PendingTermsDocid(p, iRemove);
if( rc==SQLITE_OK ){
rc = fts3DeleteTerms(p, apVal);
if( rc==SQLITE_OK ){
rc = fts3SqlExec(p, SQL_DELETE_CONTENT, apVal);
}
}
}
}
}
/* If this is an INSERT or UPDATE operation, insert the new record. */
if( nArg>1 && rc==SQLITE_OK ){
rc = fts3InsertData(p, apVal, pRowid);
if( rc==SQLITE_OK && (!isRemove || *pRowid!=iRemove) ){
rc = fts3PendingTermsDocid(p, *pRowid);
}
if( rc==SQLITE_OK ){
rc = fts3InsertTerms(p, apVal);
}
}
return rc;
}
/*
** Flush any data in the pending-terms hash table to disk. If successful,
** merge all segments in the database (including the new segment, if
** there was any data to flush) into a single segment.
*/
int sqlite3Fts3Optimize(Fts3Table *p){
int rc = sqlite3Fts3PendingTermsFlush(p);
if( rc==SQLITE_OK ){
rc = fts3SegmentMerge(p, -1);
}
return rc;
}
#endif
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