Go back to using a separate method for doing ILIKE for single byte

character encodings that doesn't involve calling lower(). This should
cure the performance regression in this case complained of by Guillaume
Smet. It still leaves the horrid performance for multi-byte encodings
introduced in 8.2, but there's no obvious solution for that in sight.

1 files changed, 35 insertions, 10 deletions

diff --git a/src/backend/utils/adt/like.c b/src/backend/utils/adt/like.c
index 1603a4e61ae..4c4ca2c1936 100644
--- a/src/backend/utils/adt/like.c
+++ b/src/backend/utils/adt/like.c
@@ -11,7 +11,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	$PostgreSQL: pgsql/src/backend/utils/adt/like.c,v 1.70 2007/09/21 22:52:52 tgl Exp $
+ *	$PostgreSQL: pgsql/src/backend/utils/adt/like.c,v 1.71 2007/09/22 03:58:34 adunstan Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -36,6 +36,8 @@ static text *MB_do_like_escape(text *, text *);
 
 static int	UTF8_MatchText(char *t, int tlen, char *p, int plen);
 
+static int	SB_IMatchText(char *t, int tlen, char *p, int plen);
+
 static int	GenericMatchText(char *s, int slen, char* p, int plen);
 static int	Generic_Text_IC_like(text *str, text *pat);
 
@@ -104,6 +106,12 @@ wchareq(char *p1, char *p2)
 
 #include "like_match.c"
 
+/* setup to compile like_match.c for single byte case insensitive matches */
+#define MATCH_LOWER
+#define NextChar(p, plen) NextByte((p), (plen))
+#define MatchText SB_IMatchText
+
+#include "like_match.c"
 
 /* setup to compile like_match.c for UTF8 encoding, using fast NextChar */
 
@@ -132,16 +140,33 @@ Generic_Text_IC_like(text *str, text *pat)
 	int			slen,
 				plen;
 
-	/* Force inputs to lower case to achieve case insensitivity */
-	str = DatumGetTextP(DirectFunctionCall1(lower, PointerGetDatum(str)));
-	pat = DatumGetTextP(DirectFunctionCall1(lower, PointerGetDatum(pat)));
-	/* lower's result is never packed, so OK to use old macros here */
-	s = VARDATA(str);
-	slen = (VARSIZE(str) - VARHDRSZ);
-	p = VARDATA(pat);
-	plen = (VARSIZE(pat) - VARHDRSZ);
+	/* For efficiency reasons, in the single byte case we don't call
+	 * lower() on the pattern and text, but instead call to_lower on each
+	 * character.  In the multi-byte case we don't have much choice :-(
+	 */
 
-	return GenericMatchText(s, slen, p, plen);
+	if (pg_database_encoding_max_length() > 1)
+	{
+		/* lower's result is never packed, so OK to use old macros here */
+		pat = DatumGetTextP(DirectFunctionCall1(lower, PointerGetDatum(pat)));
+		p = VARDATA(pat);
+		plen = (VARSIZE(pat) - VARHDRSZ);
+		str = DatumGetTextP(DirectFunctionCall1(lower, PointerGetDatum(str)));
+		s = VARDATA(str);
+		slen = (VARSIZE(str) - VARHDRSZ);
+		if (GetDatabaseEncoding() == PG_UTF8)
+			return UTF8_MatchText(s, slen, p, plen);
+		else
+			return MB_MatchText(s, slen, p, plen);
+	}
+	else
+	{
+		p = VARDATA_ANY(pat);
+		plen = VARSIZE_ANY_EXHDR(pat);
+		s = VARDATA_ANY(str);
+		slen = VARSIZE_ANY_EXHDR(str);
+		return SB_IMatchText(s, slen, p, plen);
+	}
 }
 
 /*