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Fix YA text phrase search bug.

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checkcondition_str() failed to report multiple matches for a prefix
pattern correctly: it would dutifully merge the match positions, but
then after exiting that loop, if the last prefix-matching word had
had no suitable positions, it would report there were no matches.
The upshot would be failing to recognize a match that the query
should match.

It looks like you need all of these conditions to see the bug:
* a phrase search (else we don't ask for match position details)
* a prefix search item (else we don't get to this code)
* a weight restriction (else checkclass_str won't fail)

Noted while investigating a problem report from Pavel Borisov,
though this is distinct from the issue he was on about.

Back-patch to 9.6 where phrase search was added.
This commit is contained in:
Tom Lane
2020-05-07 15:59:52 -04:00
parent 2bf56f50eb
commit 7c9d9aa5ca
3 changed files with 28 additions and 1 deletions
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8
src/backend/utils/adt/tsvector_op.c
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@ -1326,12 +1326,13 @@ checkcondition_str(void *checkval, QueryOperand *val, ExecPhraseData *data)
WordEntry *StopLow = chkval->arrb;
WordEntry *StopHigh = chkval->arre;
WordEntry *StopMiddle = StopHigh;
int difference = -1;
bool res = false;
/* Loop invariant: StopLow <= val < StopHigh */
while (StopLow < StopHigh)
{
int difference;
StopMiddle = StopLow + (StopHigh - StopLow) / 2;
difference = tsCompareString(chkval->operand + val->distance,
val->length,
@ -1397,6 +1398,11 @@ checkcondition_str(void *checkval, QueryOperand *val, ExecPhraseData *data)
memcpy(allpos + npos, data->pos, sizeof(WordEntryPos) * data->npos);
npos += data->npos;
}
else
{
/* at loop exit, res must be true if we found matches */
res = (npos > 0);
}
}
else
{