rdelaage
/
postgresql
mirror of https://git.postgresql.org/git/postgresql.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Adjust string comparison so that only bitwise-equal strings are considered 

equal: if strcoll claims two strings are equal, check it with strcmp, and
sort according to strcmp if not identical.  This fixes inconsistent
behavior under glibc's hu_HU locale, and probably under some other locales
as well.  Also, take advantage of the now-well-defined behavior to speed up
texteq, textne, bpchareq, bpcharne: they may as well just do a bitwise
comparison and not bother with strcoll at all.

NOTE: affected databases may need to REINDEX indexes on text columns to be
sure they are self-consistent.
This commit is contained in:
Tom Lane 2005-12-22 22:50:00 +00:00
parent 7b53b45a64
commit 656beff590
3 changed files with 40 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
src/backend/access/hash/hashfunc.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/hash/hashfunc.c,v 1.45 2005/10/15 02:49:08 momjian Exp $
* $PostgreSQL: pgsql/src/backend/access/hash/hashfunc.c,v 1.46 2005/12/22 22:50:00 tgl Exp $
*
* NOTES
* These functions are stored in pg_amproc. For each operator class
@ -138,9 +138,9 @@ hashtext(PG_FUNCTION_ARGS)
Datum result;
/*
* Note: this is currently identical in behavior to hashvarlena, but it
* seems likely that we may need to do something different in non-C
* locales. (See also hashbpchar, if so.)
* Note: this is currently identical in behavior to hashvarlena, but
* keep it as a separate function in case we someday want to do something
* different in non-C locales. (See also hashbpchar, if so.)
*/
result = hash_any((unsigned char *) VARDATA(key),
VARSIZE(key) - VARHDRSZ);

20
src/backend/utils/adt/varchar.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/varchar.c,v 1.113 2005/10/15 02:49:30 momjian Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/varchar.c,v 1.114 2005/12/22 22:50:00 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -614,11 +614,14 @@ bpchareq(PG_FUNCTION_ARGS)
len1 = bcTruelen(arg1);
len2 = bcTruelen(arg2);
/* fast path for different-length inputs */
/*
* Since we only care about equality or not-equality, we can avoid all
* the expense of strcoll() here, and just do bitwise comparison.
*/
if (len1 != len2)
result = false;
else
result = (varstr_cmp(VARDATA(arg1), len1, VARDATA(arg2), len2) == 0);
result = (strncmp(VARDATA(arg1), VARDATA(arg2), len1) == 0);
PG_FREE_IF_COPY(arg1, 0);
PG_FREE_IF_COPY(arg2, 1);
@ -638,11 +641,14 @@ bpcharne(PG_FUNCTION_ARGS)
len1 = bcTruelen(arg1);
len2 = bcTruelen(arg2);
/* fast path for different-length inputs */
/*
* Since we only care about equality or not-equality, we can avoid all
* the expense of strcoll() here, and just do bitwise comparison.
*/
if (len1 != len2)
result = true;
else
result = (varstr_cmp(VARDATA(arg1), len1, VARDATA(arg2), len2) != 0);
result = (strncmp(VARDATA(arg1), VARDATA(arg2), len1) != 0);
PG_FREE_IF_COPY(arg1, 0);
PG_FREE_IF_COPY(arg2, 1);
@ -789,7 +795,9 @@ bpchar_smaller(PG_FUNCTION_ARGS)
* bpchar needs a specialized hash function because we want to ignore
* trailing blanks in comparisons.
*
* XXX is there any need for locale-specific behavior here?
* Note: currently there is no need for locale-specific behavior here,
* but if we ever change the semantics of bpchar comparison to trust
* strcoll() completely, we'd need to do something different in non-C locales.
*/
Datum
hashbpchar(PG_FUNCTION_ARGS)

27
src/backend/utils/adt/varlena.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/varlena.c,v 1.141 2005/11/22 18:17:23 momjian Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/varlena.c,v 1.142 2005/12/22 22:50:00 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -938,6 +938,15 @@ varstr_cmp(char *arg1, int len1, char *arg2, int len2)
result = strcoll(a1p, a2p);
/*
* In some locales strcoll() can claim that nonidentical strings are
* equal. Believing that would be bad news for a number of reasons,
* so we follow Perl's lead and sort "equal" strings according to
* strcmp().
*/
if (result == 0)
result = strcmp(a1p, a2p);
if (a1p != a1buf)
pfree(a1p);
if (a2p != a2buf)
@ -984,11 +993,15 @@ texteq(PG_FUNCTION_ARGS)
text *arg2 = PG_GETARG_TEXT_P(1);
bool result;
/* fast path for different-length inputs */
/*
* Since we only care about equality or not-equality, we can avoid all
* the expense of strcoll() here, and just do bitwise comparison.
*/
if (VARSIZE(arg1) != VARSIZE(arg2))
result = false;
else
result = (text_cmp(arg1, arg2) == 0);
result = (strncmp(VARDATA(arg1), VARDATA(arg2),
VARSIZE(arg1) - VARHDRSZ) == 0);
PG_FREE_IF_COPY(arg1, 0);
PG_FREE_IF_COPY(arg2, 1);
@ -1003,11 +1016,15 @@ textne(PG_FUNCTION_ARGS)
text *arg2 = PG_GETARG_TEXT_P(1);
bool result;
/* fast path for different-length inputs */
/*
* Since we only care about equality or not-equality, we can avoid all
* the expense of strcoll() here, and just do bitwise comparison.
*/
if (VARSIZE(arg1) != VARSIZE(arg2))
result = true;
else
result = (text_cmp(arg1, arg2) != 0);
result = (strncmp(VARDATA(arg1), VARDATA(arg2),
VARSIZE(arg1) - VARHDRSZ) != 0);
PG_FREE_IF_COPY(arg1, 0);
PG_FREE_IF_COPY(arg2, 1);