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Fix a performance problem in the FTS4 auxiliary functions triggered by an OR clause in the full-text query.

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FossilOrigin-Name: fa0f2f0e3e79ae653118b901e1cca7725dfaf249
This commit is contained in:
dan
2013-09-30 18:14:45 +00:00
parent 92054fefcd
commit 1f03e609ff
4 changed files with 129 additions and 30 deletions
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78
ext/fts3/fts3.c
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@ -5268,15 +5268,23 @@ int sqlite3Fts3EvalPhrasePoslist(
pIter = pPhrase->doclist.pList;
if( iDocid!=pCsr->iPrevId || pExpr->bEof ){
int bDescDoclist = pTab->bDescIdx; /* For DOCID_CMP macro */
int iMul; /* +1 if csr dir matches index dir, else -1 */
int bOr = 0;
u8 bEof = 0;
Fts3Expr *p;
u8 bTreeEof = 0;
Fts3Expr *p; /* Used to iterate from pExpr to root */
Fts3Expr *pNear; /* Most senior NEAR ancestor (or pExpr) */
/* Check if this phrase descends from an OR expression node. If not,
** return NULL. Otherwise, the entry that corresponds to docid
** pCsr->iPrevId may lie earlier in the doclist buffer. */
** pCsr->iPrevId may lie earlier in the doclist buffer. Or, if the
** tree that the node is part of has been marked as EOF, but the node
** itself is not EOF, then it may point to an earlier entry. */
pNear = pExpr;
for(p=pExpr->pParent; p; p=p->pParent){
if( p->eType==FTSQUERY_OR ) bOr = 1;
if( p->eType==FTSQUERY_NEAR ) pNear = p;
if( p->bEof ) bTreeEof = 1;
}
if( bOr==0 ) return SQLITE_OK;
@ -5295,29 +5303,59 @@ int sqlite3Fts3EvalPhrasePoslist(
assert( rc!=SQLITE_OK || pPhrase->bIncr==0 );
if( rc!=SQLITE_OK ) return rc;
}
if( pExpr->bEof ){
pIter = 0;
iDocid = 0;
iMul = ((pCsr->bDesc==bDescDoclist) ? 1 : -1);
while( bTreeEof==1
&& pNear->bEof==0
&& (DOCID_CMP(pNear->iDocid, pCsr->iPrevId) * iMul)<0
){
int rc = SQLITE_OK;
fts3EvalNextRow(pCsr, pExpr, &rc);
if( rc!=SQLITE_OK ) return rc;
iDocid = pExpr->iDocid;
pIter = pPhrase->doclist.pList;
}
bEof = (pPhrase->doclist.nAll==0);
assert( bDescDoclist==0 || bDescDoclist==1 );
assert( pCsr->bDesc==0 || pCsr->bDesc==1 );
if( pCsr->bDesc==bDescDoclist ){
int dummy;
while( (pIter==0 || DOCID_CMP(iDocid, pCsr->iPrevId)>0 ) && bEof==0 ){
sqlite3Fts3DoclistPrev(
bDescDoclist, pPhrase->doclist.aAll, pPhrase->doclist.nAll,
&pIter, &iDocid, &dummy, &bEof
);
}
}else{
while( (pIter==0 || DOCID_CMP(iDocid, pCsr->iPrevId)<0 ) && bEof==0 ){
sqlite3Fts3DoclistNext(
bDescDoclist, pPhrase->doclist.aAll, pPhrase->doclist.nAll,
&pIter, &iDocid, &bEof
);
if( bEof==0 ){
if( pCsr->bDesc==bDescDoclist ){
int dummy;
if( pNear->bEof ){
/* This expression is already at EOF. So position it to point to the
** last entry in the doclist at pPhrase->doclist.aAll[]. Variable
** iDocid is already set for this entry, so all that is required is
** to set pIter to point to the first byte of the last position-list
** in the doclist.
**
** It would also be correct to set pIter and iDocid to zero. In
** this case, the first call to sqltie3Fts4DoclistPrev() below
** would also move the iterator to point to the last entry in the
** doclist. However, this is expensive, as to do so it has to
** iterate through the entire doclist from start to finish (since
** it does not know the docid for the last entry). */
pIter = &pPhrase->doclist.aAll[pPhrase->doclist.nAll-1];
fts3ReversePoslist(pPhrase->doclist.aAll, &pIter);
}
while( (pIter==0 || DOCID_CMP(iDocid, pCsr->iPrevId)>0 ) && bEof==0 ){
sqlite3Fts3DoclistPrev(
bDescDoclist, pPhrase->doclist.aAll, pPhrase->doclist.nAll,
&pIter, &iDocid, &dummy, &bEof
);
}
}else{
if( pNear->bEof ){
pIter = 0;
iDocid = 0;
}
while( (pIter==0 || DOCID_CMP(iDocid, pCsr->iPrevId)<0 ) && bEof==0 ){
sqlite3Fts3DoclistNext(
bDescDoclist, pPhrase->doclist.aAll, pPhrase->doclist.nAll,
&pIter, &iDocid, &bEof
);
}
}
}