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Make exact distance match for FTS phrase operator

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Phrase operator now requires exact distance betweens lexems instead of
less-or-equal.

Per discussion c19fcfec308e6ccd952cdde9e648b505@mail.gmail.com
This commit is contained in:
Teodor Sigaev
2016-06-27 20:41:00 +03:00
parent f1993038a4
commit 028350f619
4 changed files with 63 additions and 47 deletions
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65
src/backend/utils/adt/tsvector_op.c
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@ -1375,6 +1375,7 @@ TS_phrase_execute(QueryItem *curitem,
ExecPhraseData Ldata = {0, false, NULL},
Rdata = {0, false, NULL};
WordEntryPos *Lpos,
*LposStart,
*Rpos,
*pos_iter = NULL;
@ -1416,52 +1417,60 @@ TS_phrase_execute(QueryItem *curitem,
pos_iter = data->pos;
}
Lpos = Ldata.pos;
Rpos = Rdata.pos;
/*
* Find matches by distance, WEP_GETPOS() is needed because
* ExecPhraseData->data can point to the tsvector's WordEntryPosVector
*/
Rpos = Rdata.pos;
LposStart = Ldata.pos;
while (Rpos < Rdata.pos + Rdata.npos)
{
/*
* We need to check all possible distances, so reset Lpos
* to guranteed not yet satisfied position.
*/
Lpos = LposStart;
while (Lpos < Ldata.pos + Ldata.npos)
{
if (WEP_GETPOS(*Lpos) <= WEP_GETPOS(*Rpos))
if (WEP_GETPOS(*Rpos) - WEP_GETPOS(*Lpos) ==
curitem->qoperator.distance)
{
/*
* Lpos is behind the Rpos, so we have to check the
* distance condition
*/
if (WEP_GETPOS(*Rpos) - WEP_GETPOS(*Lpos) <= curitem->qoperator.distance)
/* MATCH! */
if (data)
{
/* MATCH! */
if (data)
{
*pos_iter = WEP_GETPOS(*Rpos);
pos_iter++;
/* Store position for upper phrase operator */
*pos_iter = WEP_GETPOS(*Rpos);
pos_iter++;
break; /* We need to build a unique result
* array, so go to the next Rpos */
}
else
{
/*
* We are in the root of the phrase tree and hence
* we don't have to store the resulting positions
*/
return true;
}
/*
* Set left start position to next, because current one
* could not satisfy distance for any other right
* position
*/
LposStart = Lpos + 1;
break;
}
else
{
/*
* We are in the root of the phrase tree and hence
* we don't have to store the resulting positions
*/
return true;
}
}
else
else if (WEP_GETPOS(*Rpos) <= WEP_GETPOS(*Lpos) ||
WEP_GETPOS(*Rpos) - WEP_GETPOS(*Lpos) <
curitem->qoperator.distance)
{
/*
* Go to the next Rpos, because Lpos is ahead of the
* current Rpos
* Go to the next Rpos, because Lpos is ahead or on less
* distance than required by current operator
*/
break;
}
Lpos++;