database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-06-16 06:01:02 +03:00
Code Activity

Fix range-query estimation to not double-exclude NULLs, per gripe from

Browse Source 
Ray Ontko 28-June-02.  Also, fix prefix_selectivity for NAME lefthand
variables (it was bogusly assuming binary compatibility), and adjust
make_greater_string() to not call pg_mbcliplen() with invalid multibyte
data (this last per bug report that I can't find at the moment, but it
was in July '02).
This commit is contained in:
Tom Lane
2002-10-19 02:56:16 +00:00
parent a3cb8746d9
commit c0f7dcdac1
3 changed files with 49 additions and 36 deletions
Download Patch File Download Diff File Expand all files Collapse all files

58
src/backend/utils/adt/selfuncs.c
View File

@ -15,7 +15,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/utils/adt/selfuncs.c,v 1.118 2002/09/20 03:55:40 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/utils/adt/selfuncs.c,v 1.119 2002/10/19 02:56:16 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -1007,10 +1007,9 @@ icnlikesel(PG_FUNCTION_ARGS)
* booltestsel - Selectivity of BooleanTest Node.
*/
Selectivity
booltestsel(Query *root, BooleanTest *clause, int varRelid)
booltestsel(Query *root, BoolTestType booltesttype, Node *arg, int varRelid)
{
Var *var;
Node *arg;
Oid relid;
HeapTuple statsTuple;
Datum *values;
@ -1019,10 +1018,6 @@ booltestsel(Query *root, BooleanTest *clause, int varRelid)
int nnumbers;
double selec;
Assert(clause && IsA(clause, BooleanTest));
arg = (Node *) clause->arg;
/*
* Ignore any binary-compatible relabeling (probably unnecessary, but
* can't hurt)
@ -1040,7 +1035,7 @@ booltestsel(Query *root, BooleanTest *clause, int varRelid)
* the possibility of a NULL value when using clause_selectivity,
* and just assume the value is either TRUE or FALSE.
*/
switch (clause->booltesttype)
switch (booltesttype)
{
case IS_UNKNOWN:
selec = DEFAULT_UNK_SEL;
@ -1058,7 +1053,7 @@ booltestsel(Query *root, BooleanTest *clause, int varRelid)
break;
default:
elog(ERROR, "booltestsel: unexpected booltesttype %d",
(int) clause->booltesttype);
(int) booltesttype);
selec = 0.0; /* Keep compiler quiet */
break;
}
@ -1107,7 +1102,7 @@ booltestsel(Query *root, BooleanTest *clause, int varRelid)
*/
freq_false = 1.0 - freq_true - freq_null;
switch (clause->booltesttype)
switch (booltesttype)
{
case IS_UNKNOWN:
/* select only NULL values */
@ -1135,7 +1130,7 @@ booltestsel(Query *root, BooleanTest *clause, int varRelid)
break;
default:
elog(ERROR, "booltestsel: unexpected booltesttype %d",
(int) clause->booltesttype);
(int) booltesttype);
selec = 0.0; /* Keep compiler quiet */
break;
}
@ -1151,7 +1146,7 @@ booltestsel(Query *root, BooleanTest *clause, int varRelid)
* Otherwise adjust for null fraction and assume an even split
* for boolean tests.
*/
switch (clause->booltesttype)
switch (booltesttype)
{
case IS_UNKNOWN:
@ -1176,7 +1171,7 @@ booltestsel(Query *root, BooleanTest *clause, int varRelid)
break;
default:
elog(ERROR, "booltestsel: unexpected booltesttype %d",
(int) clause->booltesttype);
(int) booltesttype);
selec = 0.0; /* Keep compiler quiet */
break;
}
@ -1190,7 +1185,7 @@ booltestsel(Query *root, BooleanTest *clause, int varRelid)
* No VACUUM ANALYZE stats available, so use a default value.
* (Note: not much point in recursing to clause_selectivity here.)
*/
switch (clause->booltesttype)
switch (booltesttype)
{
case IS_UNKNOWN:
selec = DEFAULT_UNK_SEL;
@ -1206,7 +1201,7 @@ booltestsel(Query *root, BooleanTest *clause, int varRelid)
break;
default:
elog(ERROR, "booltestsel: unexpected booltesttype %d",
(int) clause->booltesttype);
(int) booltesttype);
selec = 0.0; /* Keep compiler quiet */
break;
}
@ -1222,19 +1217,16 @@ booltestsel(Query *root, BooleanTest *clause, int varRelid)
* nulltestsel - Selectivity of NullTest Node.
*/
Selectivity
nulltestsel(Query *root, NullTest *clause, int varRelid)
nulltestsel(Query *root, NullTestType nulltesttype, Node *arg, int varRelid)
{
Var *var;
Node *arg;
Oid relid;
HeapTuple statsTuple;
double selec;
double defselec;
double freq_null;
Assert(clause && IsA(clause, NullTest));
switch (clause->nulltesttype)
switch (nulltesttype)
{
case IS_NULL:
defselec = DEFAULT_UNK_SEL;
@ -1244,25 +1236,22 @@ nulltestsel(Query *root, NullTest *clause, int varRelid)
break;
default:
elog(ERROR, "nulltestsel: unexpected nulltesttype %d",
(int) clause->nulltesttype);
(int) nulltesttype);
return (Selectivity) 0; /* keep compiler quiet */
}
arg = (Node *) clause->arg;
/*
* Ignore any binary-compatible relabeling
*/
if (IsA(arg, RelabelType))
arg = ((RelabelType *) arg)->arg;
if (IsA(arg, Var) &&(varRelid == 0 || varRelid == ((Var *) arg)->varno))
if (IsA(arg, Var) &&
(varRelid == 0 || varRelid == ((Var *) arg)->varno))
var = (Var *) arg;
else
{
/*
* punt if non-Var argument
*/
/* punt if non-Var argument */
return (Selectivity) defselec;
}
@ -1282,7 +1271,7 @@ nulltestsel(Query *root, NullTest *clause, int varRelid)
stats = (Form_pg_statistic) GETSTRUCT(statsTuple);
freq_null = stats->stanullfrac;
switch (clause->nulltesttype)
switch (nulltesttype)
{
case IS_NULL:
@ -1301,7 +1290,7 @@ nulltestsel(Query *root, NullTest *clause, int varRelid)
break;
default:
elog(ERROR, "nulltestsel: unexpected nulltesttype %d",
(int) clause->nulltesttype);
(int) nulltesttype);
return (Selectivity) 0; /* keep compiler quiet */
}
@ -2978,6 +2967,10 @@ prefix_selectivity(Query *root, Var *var, Const *prefixcon)
else
prefix = DatumGetCString(DirectFunctionCall1(byteaout, prefixcon->constvalue));
/* If var is type NAME, must adjust type of comparison constant */
if (var->vartype == NAMEOID)
prefixcon = string_to_const(prefix, NAMEOID);
cmpargs = makeList2(var, prefixcon);
/* Assume scalargtsel is appropriate for all supported types */
prefixsel = DatumGetFloat8(DirectFunctionCall4(scalargtsel,
@ -3014,6 +3007,9 @@ prefix_selectivity(Query *root, Var *var, Const *prefixcon)
*/
prefixsel = topsel + prefixsel - 1.0;
/* Adjust for double-exclusion of NULLs */
prefixsel += nulltestsel(root, IS_NULL, (Node *) var, var->varno);
/*
* A zero or slightly negative prefixsel should be converted into
* a small positive value; we probably are dealing with a very
@ -3351,6 +3347,7 @@ make_greater_string(const Const *str_const)
while (len > 0)
{
unsigned char *lastchar = (unsigned char *) (workstr + len - 1);
unsigned char savelastchar = *lastchar;
/*
* Try to generate a larger string by incrementing the last byte.
@ -3369,6 +3366,9 @@ make_greater_string(const Const *str_const)
}
}
/* restore last byte so we don't confuse pg_mbcliplen */
*lastchar = savelastchar;
/*
* Truncate off the last character, which might be more than 1
* byte, depending on the character encoding.