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Fix patternsel() and callers to do the right thing for NOT LIKE and the other 

negated-match operators.  patternsel had been using the supplied operator as
though it were a positive-match operator, and thus obtaining a wrong result,
which was even more wrong after the caller subtracted it from 1.  Seems
cleanest to give patternsel an explicit "negate" argument so that it knows
what's going on.  Also install the same factorization scheme for pattern
join selectivity estimators; even though they are just stubs at the
moment, this may keep someone from making the same type of mistake when
they get filled out.  Per report from Greg Mullane.

Backpatch to 8.2 --- previous releases do not show the problem because
patternsel() doesn't actually use the operator directly.
This commit is contained in:
Tom Lane 2007-11-07 21:00:37 +00:00
parent 371d7bc7c0
commit 9542287123
1 changed files with 52 additions and 57 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

109
src/backend/utils/adt/selfuncs.c
View File

@ -15,7 +15,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.236 2007/08/31 23:35:22 tgl Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.237 2007/11/07 21:00:37 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -901,7 +901,7 @@ scalargtsel(PG_FUNCTION_ARGS)
* patternsel - Generic code for pattern-match selectivity.
*/
static double
patternsel(PG_FUNCTION_ARGS, Pattern_Type ptype)
patternsel(PG_FUNCTION_ARGS, Pattern_Type ptype, bool negate)
{
PlannerInfo *root = (PlannerInfo *) PG_GETARG_POINTER(0);
Oid operator = PG_GETARG_OID(1);
@ -921,23 +921,40 @@ patternsel(PG_FUNCTION_ARGS, Pattern_Type ptype)
Const *rest = NULL;
double result;
/*
* If this is for a NOT LIKE or similar operator, get the corresponding
* positive-match operator and work with that. Set result to the
* correct default estimate, too.
*/
if (negate)
{
operator = get_negator(operator);
if (!OidIsValid(operator))
elog(ERROR, "patternsel called for operator without a negator");
result = 1.0 - DEFAULT_MATCH_SEL;
}
else
{
result = DEFAULT_MATCH_SEL;
}
/*
* If expression is not variable op constant, then punt and return a
* default estimate.
*/
if (!get_restriction_variable(root, args, varRelid,
&vardata, &other, &varonleft))
return DEFAULT_MATCH_SEL;
return result;
if (!varonleft || !IsA(other, Const))
{
ReleaseVariableStats(vardata);
return DEFAULT_MATCH_SEL;
return result;
}
variable = (Node *) linitial(args);
/*
* If the constant is NULL, assume operator is strict and return zero, ie,
* operator will never return TRUE.
* operator will never return TRUE. (It's zero even for a negator op.)
*/
if (((Const *) other)->constisnull)
{
@ -956,7 +973,7 @@ patternsel(PG_FUNCTION_ARGS, Pattern_Type ptype)
if (consttype != TEXTOID && consttype != BYTEAOID)
{
ReleaseVariableStats(vardata);
return DEFAULT_MATCH_SEL;
return result;
}
/*
@ -988,7 +1005,7 @@ patternsel(PG_FUNCTION_ARGS, Pattern_Type ptype)
break;
default:
ReleaseVariableStats(vardata);
return DEFAULT_MATCH_SEL;
return result;
}
/* divide pattern into fixed prefix and remainder */
@ -1017,7 +1034,7 @@ patternsel(PG_FUNCTION_ARGS, Pattern_Type ptype)
elog(ERROR, "unrecognized consttype: %u",
prefix->consttype);
ReleaseVariableStats(vardata);
return DEFAULT_MATCH_SEL;
return result;
}
prefix = string_to_const(prefixstr, vartype);
pfree(prefixstr);
@ -1125,7 +1142,7 @@ patternsel(PG_FUNCTION_ARGS, Pattern_Type ptype)
ReleaseVariableStats(vardata);
return result;
return negate ? (1.0 - result) : result;
}
/*
@ -1134,7 +1151,7 @@ patternsel(PG_FUNCTION_ARGS, Pattern_Type ptype)
Datum
regexeqsel(PG_FUNCTION_ARGS)
{
PG_RETURN_FLOAT8(patternsel(fcinfo, Pattern_Type_Regex));
PG_RETURN_FLOAT8(patternsel(fcinfo, Pattern_Type_Regex, false));
}
/*
@ -1143,7 +1160,7 @@ regexeqsel(PG_FUNCTION_ARGS)
Datum
icregexeqsel(PG_FUNCTION_ARGS)
{
PG_RETURN_FLOAT8(patternsel(fcinfo, Pattern_Type_Regex_IC));
PG_RETURN_FLOAT8(patternsel(fcinfo, Pattern_Type_Regex_IC, false));
}
/*
@ -1152,7 +1169,7 @@ icregexeqsel(PG_FUNCTION_ARGS)
Datum
likesel(PG_FUNCTION_ARGS)
{
PG_RETURN_FLOAT8(patternsel(fcinfo, Pattern_Type_Like));
PG_RETURN_FLOAT8(patternsel(fcinfo, Pattern_Type_Like, false));
}
/*
@ -1161,7 +1178,7 @@ likesel(PG_FUNCTION_ARGS)
Datum
iclikesel(PG_FUNCTION_ARGS)
{
PG_RETURN_FLOAT8(patternsel(fcinfo, Pattern_Type_Like_IC));
PG_RETURN_FLOAT8(patternsel(fcinfo, Pattern_Type_Like_IC, false));
}
/*
@ -1170,11 +1187,7 @@ iclikesel(PG_FUNCTION_ARGS)
Datum
regexnesel(PG_FUNCTION_ARGS)
{
double result;
result = patternsel(fcinfo, Pattern_Type_Regex);
result = 1.0 - result;
PG_RETURN_FLOAT8(result);
PG_RETURN_FLOAT8(patternsel(fcinfo, Pattern_Type_Regex, true));
}
/*
@ -1183,11 +1196,7 @@ regexnesel(PG_FUNCTION_ARGS)
Datum
icregexnesel(PG_FUNCTION_ARGS)
{
double result;
result = patternsel(fcinfo, Pattern_Type_Regex_IC);
result = 1.0 - result;
PG_RETURN_FLOAT8(result);
PG_RETURN_FLOAT8(patternsel(fcinfo, Pattern_Type_Regex_IC, true));
}
/*
@ -1196,11 +1205,7 @@ icregexnesel(PG_FUNCTION_ARGS)
Datum
nlikesel(PG_FUNCTION_ARGS)
{
double result;
result = patternsel(fcinfo, Pattern_Type_Like);
result = 1.0 - result;
PG_RETURN_FLOAT8(result);
PG_RETURN_FLOAT8(patternsel(fcinfo, Pattern_Type_Like, true));
}
/*
@ -1209,11 +1214,7 @@ nlikesel(PG_FUNCTION_ARGS)
Datum
icnlikesel(PG_FUNCTION_ARGS)
{
double result;
result = patternsel(fcinfo, Pattern_Type_Like_IC);
result = 1.0 - result;
PG_RETURN_FLOAT8(result);
PG_RETURN_FLOAT8(patternsel(fcinfo, Pattern_Type_Like_IC, true));
}
/*
@ -2081,13 +2082,23 @@ scalargtjoinsel(PG_FUNCTION_ARGS)
PG_RETURN_FLOAT8(DEFAULT_INEQ_SEL);
}
/*
* patternjoinsel - Generic code for pattern-match join selectivity.
*/
static double
patternjoinsel(PG_FUNCTION_ARGS, Pattern_Type ptype, bool negate)
{
/* For the moment we just punt. */
return negate ? (1.0 - DEFAULT_MATCH_SEL) : DEFAULT_MATCH_SEL;
}
/*
* regexeqjoinsel - Join selectivity of regular-expression pattern match.
*/
Datum
regexeqjoinsel(PG_FUNCTION_ARGS)
{
PG_RETURN_FLOAT8(DEFAULT_MATCH_SEL);
PG_RETURN_FLOAT8(patternjoinsel(fcinfo, Pattern_Type_Regex, false));
}
/*
@ -2096,7 +2107,7 @@ regexeqjoinsel(PG_FUNCTION_ARGS)
Datum
icregexeqjoinsel(PG_FUNCTION_ARGS)
{
PG_RETURN_FLOAT8(DEFAULT_MATCH_SEL);
PG_RETURN_FLOAT8(patternjoinsel(fcinfo, Pattern_Type_Regex_IC, false));
}
/*
@ -2105,7 +2116,7 @@ icregexeqjoinsel(PG_FUNCTION_ARGS)
Datum
likejoinsel(PG_FUNCTION_ARGS)
{
PG_RETURN_FLOAT8(DEFAULT_MATCH_SEL);
PG_RETURN_FLOAT8(patternjoinsel(fcinfo, Pattern_Type_Like, false));
}
/*
@ -2114,7 +2125,7 @@ likejoinsel(PG_FUNCTION_ARGS)
Datum
iclikejoinsel(PG_FUNCTION_ARGS)
{
PG_RETURN_FLOAT8(DEFAULT_MATCH_SEL);
PG_RETURN_FLOAT8(patternjoinsel(fcinfo, Pattern_Type_Like_IC, false));
}
/*
@ -2123,11 +2134,7 @@ iclikejoinsel(PG_FUNCTION_ARGS)
Datum
regexnejoinsel(PG_FUNCTION_ARGS)
{
float8 result;
result = DatumGetFloat8(regexeqjoinsel(fcinfo));
result = 1.0 - result;
PG_RETURN_FLOAT8(result);
PG_RETURN_FLOAT8(patternjoinsel(fcinfo, Pattern_Type_Regex, true));
}
/*
@ -2136,11 +2143,7 @@ regexnejoinsel(PG_FUNCTION_ARGS)
Datum
icregexnejoinsel(PG_FUNCTION_ARGS)
{
float8 result;
result = DatumGetFloat8(icregexeqjoinsel(fcinfo));
result = 1.0 - result;
PG_RETURN_FLOAT8(result);
PG_RETURN_FLOAT8(patternjoinsel(fcinfo, Pattern_Type_Regex_IC, true));
}
/*
@ -2149,11 +2152,7 @@ icregexnejoinsel(PG_FUNCTION_ARGS)
Datum
nlikejoinsel(PG_FUNCTION_ARGS)
{
float8 result;
result = DatumGetFloat8(likejoinsel(fcinfo));
result = 1.0 - result;
PG_RETURN_FLOAT8(result);
PG_RETURN_FLOAT8(patternjoinsel(fcinfo, Pattern_Type_Like, true));
}
/*
@ -2162,11 +2161,7 @@ nlikejoinsel(PG_FUNCTION_ARGS)
Datum
icnlikejoinsel(PG_FUNCTION_ARGS)
{
float8 result;
result = DatumGetFloat8(iclikejoinsel(fcinfo));
result = 1.0 - result;
PG_RETURN_FLOAT8(result);
PG_RETURN_FLOAT8(patternjoinsel(fcinfo, Pattern_Type_Like_IC, true));
}
/*