Fix regex_fixed_prefix() to cope reasonably well with regex patterns of the

form '^(foo)$'.  Before, these could never be optimized into indexscans.
The recent changes to make psql and pg_dump generate such patterns (for \d
commands and -t and related switches, respectively) therefore represented
a big performance hit for people with large pg_class catalogs, as seen in
recent gripe from Erik Jones.  While at it, be more paranoid about
case-sensitivity checking in multibyte encodings, and fix some other
corner cases in which a regex might be interpreted too liberally.

1 files changed, 10 insertions, 1 deletions

diff --git a/src/backend/utils/adt/regexp.c b/src/backend/utils/adt/regexp.c
index d249772064b..a477d833205 100644
--- a/src/backend/utils/adt/regexp.c
+++ b/src/backend/utils/adt/regexp.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/regexp.c,v 1.66 2006/10/04 00:29:59 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/regexp.c,v 1.67 2007/01/03 22:39:26 tgl Exp $
  *
  *		Alistair Crooks added the code for the regex caching
  *		agc - cached the regular expressions used - there's a good chance
@@ -624,3 +624,12 @@ similar_escape(PG_FUNCTION_ARGS)
 
 	PG_RETURN_TEXT_P(result);
 }
+
+/*
+ * report whether regex_flavor is currently BASIC
+ */
+bool
+regex_flavor_is_basic(void)
+{
+	return (regex_flavor == REG_BASIC);
+}