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Fix up core tsquery GIN support for new extractQuery API.

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No need for the empty-prefix-match kluge to force a full scan anymore.
This commit is contained in:
Tom Lane
2011-01-09 14:34:50 -05:00
parent 304845075c
commit 52fd2d65a3
3 changed files with 96 additions and 53 deletions
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73
src/backend/utils/adt/tsvector_op.c
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@ -525,7 +525,8 @@ tsvector_concat(PG_FUNCTION_ARGS)
/*
* Compare two strings by tsvector rules.
* if isPrefix = true then it returns not-zero value if b has prefix a
*
* if isPrefix = true then it returns zero value iff b has prefix a
*/
int4
tsCompareString(char *a, int lena, char *b, int lenb, bool prefix)
@ -535,8 +536,7 @@ tsCompareString(char *a, int lena, char *b, int lenb, bool prefix)
if (lena == 0)
{
if (prefix)
cmp = 0; /* emtry string is equal to any if a prefix
* match */
cmp = 0; /* empty string is prefix of anything */
else
cmp = (lenb > 0) ? -1 : 0;
}
@ -551,14 +551,9 @@ tsCompareString(char *a, int lena, char *b, int lenb, bool prefix)
if (prefix)
{
if (cmp == 0 && lena > lenb)
{
/*
* b argument is not beginning with argument a
*/
cmp = 1;
}
cmp = 1; /* a is longer, so not a prefix of b */
}
else if ((cmp == 0) && (lena != lenb))
else if (cmp == 0 && lena != lenb)
{
cmp = (lena < lenb) ? -1 : 1;
}
@ -650,13 +645,13 @@ checkcondition_str(void *checkval, QueryOperand *val)
}
/*
* check for boolean condition.
* Evaluate tsquery boolean expression.
*
* if calcnot is false, NOT expressions are always evaluated to be true. This is used in ranking.
* chkcond is a callback function used to evaluate each VAL node in the query.
* checkval can be used to pass information to the callback. TS_execute doesn't
* do anything with it.
* chkcond is a callback function used to evaluate each VAL node in the query.
*
* if calcnot is false, NOT expressions are always evaluated to be true. This
* is used in ranking.
*/
bool
TS_execute(QueryItem *curitem, void *checkval, bool calcnot,
@ -675,6 +670,7 @@ TS_execute(QueryItem *curitem, void *checkval, bool calcnot,
return !TS_execute(curitem + 1, checkval, calcnot, chkcond);
else
return true;
case OP_AND:
if (TS_execute(curitem + curitem->qoperator.left, checkval, calcnot, chkcond))
return TS_execute(curitem + 1, checkval, calcnot, chkcond);
@ -695,6 +691,55 @@ TS_execute(QueryItem *curitem, void *checkval, bool calcnot,
return false;
}
/*
* Detect whether a tsquery boolean expression requires any positive matches
* to values shown in the tsquery.
*
* This is needed to know whether a GIN index search requires full index scan.
* For example, 'x & !y' requires a match of x, so it's sufficient to scan
* entries for x; but 'x | !y' could match rows containing neither x nor y.
*/
bool
tsquery_requires_match(QueryItem *curitem)
{
/* since this function recurses, it could be driven to stack overflow */
check_stack_depth();
if (curitem->type == QI_VAL)
return true;
switch (curitem->qoperator.oper)
{
case OP_NOT:
/*
* Assume there are no required matches underneath a NOT. For
* some cases with nested NOTs, we could prove there's a required
* match, but it seems unlikely to be worth the trouble.
*/
return false;
case OP_AND:
/* If either side requires a match, we're good */
if (tsquery_requires_match(curitem + curitem->qoperator.left))
return true;
else
return tsquery_requires_match(curitem + 1);
case OP_OR:
/* Both sides must require a match */
if (tsquery_requires_match(curitem + curitem->qoperator.left))
return tsquery_requires_match(curitem + 1);
else
return false;
default:
elog(ERROR, "unrecognized operator: %d", curitem->qoperator.oper);
}
/* not reachable, but keep compiler quiet */
return false;
}
/*
* boolean operations
*/