aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorTom Lane <tgl@sss.pgh.pa.us>2005-12-22 22:50:22 +0000
committerTom Lane <tgl@sss.pgh.pa.us>2005-12-22 22:50:22 +0000
commit0862aeaeec46153337df89c9c0d4d25e6d5c7713 (patch)
tree81c593f13c90b52a494c2ace5eadbb601d52ccfb
parentb1ea82fee14c457a76ac65efca58155240dab950 (diff)
downloadpostgresql-0862aeaeec46153337df89c9c0d4d25e6d5c7713.tar.gz
postgresql-0862aeaeec46153337df89c9c0d4d25e6d5c7713.zip
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.
-rw-r--r--src/backend/utils/adt/varchar.c20
-rw-r--r--src/backend/utils/adt/varlena.c27
2 files changed, 36 insertions, 11 deletions
diff --git a/src/backend/utils/adt/varchar.c b/src/backend/utils/adt/varchar.c
index 0982fb95d4f..0fe34439178 100644
--- a/src/backend/utils/adt/varchar.c
+++ b/src/backend/utils/adt/varchar.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/utils/adt/varchar.c,v 1.102 2003/08/04 04:03:10 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/utils/adt/varchar.c,v 1.102.4.1 2005/12/22 22:50:22 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -549,11 +549,14 @@ 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);
@@ -573,11 +576,14 @@ 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);
@@ -690,7 +696,9 @@ bpcharcmp(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)
diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c
index 7b17b50aec4..02721aece84 100644
--- a/src/backend/utils/adt/varlena.c
+++ b/src/backend/utils/adt/varlena.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/utils/adt/varlena.c,v 1.106.2.4 2004/02/21 00:35:13 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/utils/adt/varlena.c,v 1.106.2.5 2005/12/22 22:50:22 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -868,6 +868,15 @@ 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 (len1 >= STACKBUFLEN)
pfree(a1p);
if (len2 >= STACKBUFLEN)
@@ -920,11 +929,15 @@ 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);
@@ -939,11 +952,15 @@ 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);