Call pg_newlocale_from_collation() also with default collation

Previously, callers of pg_newlocale_from_collation() did not call it
if the collation was DEFAULT_COLLATION_OID and instead proceeded with
a pg_locale_t of 0.  Instead, now we call it anyway and have it return
0 if the default collation was passed.  It already did this, so we
just have to adjust the callers.  This simplifies all the call sites
and also makes future enhancements easier.

After discussion and testing, the previous comment in pg_locale.c
about avoiding this for performance reasons may have been mistaken
since it was testing a very different patch version way back when.

Reviewed-by: Julien Rouhaud <rjuju123@gmail.com>
Discussion: https://www.postgresql.org/message-id/ed3baa81-7fac-7788-cc12-41e3f7917e34@enterprisedb.com

1 files changed, 18 insertions, 19 deletions

diff --git a/src/backend/utils/adt/like.c b/src/backend/utils/adt/like.c
index 9f241dc7c66..833ee8f814c 100644
--- a/src/backend/utils/adt/like.c
+++ b/src/backend/utils/adt/like.c
@@ -150,7 +150,7 @@ SB_lower_char(unsigned char c, pg_locale_t locale, bool locale_is_c)
 static inline int
 GenericMatchText(const char *s, int slen, const char *p, int plen, Oid collation)
 {
-	if (collation && !lc_ctype_is_c(collation) && collation != DEFAULT_COLLATION_OID)
+	if (collation && !lc_ctype_is_c(collation))
 	{
 		pg_locale_t locale = pg_newlocale_from_collation(collation);
 
@@ -178,28 +178,27 @@ Generic_Text_IC_like(text *str, text *pat, Oid collation)
 	pg_locale_t locale = 0;
 	bool		locale_is_c = false;
 
+	if (!OidIsValid(collation))
+	{
+		/*
+		 * This typically means that the parser could not resolve a
+		 * conflict of implicit collations, so report it that way.
+		 */
+		ereport(ERROR,
+				(errcode(ERRCODE_INDETERMINATE_COLLATION),
+				 errmsg("could not determine which collation to use for ILIKE"),
+				 errhint("Use the COLLATE clause to set the collation explicitly.")));
+	}
+
 	if (lc_ctype_is_c(collation))
 		locale_is_c = true;
-	else if (collation != DEFAULT_COLLATION_OID)
-	{
-		if (!OidIsValid(collation))
-		{
-			/*
-			 * This typically means that the parser could not resolve a
-			 * conflict of implicit collations, so report it that way.
-			 */
-			ereport(ERROR,
-					(errcode(ERRCODE_INDETERMINATE_COLLATION),
-					 errmsg("could not determine which collation to use for ILIKE"),
-					 errhint("Use the COLLATE clause to set the collation explicitly.")));
-		}
+	else
 		locale = pg_newlocale_from_collation(collation);
 
-		if (locale && !locale->deterministic)
-			ereport(ERROR,
-					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-					 errmsg("nondeterministic collations are not supported for ILIKE")));
-	}
+	if (locale && !locale->deterministic)
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("nondeterministic collations are not supported for ILIKE")));
 
 	/*
 	 * For efficiency reasons, in the single byte case we don't call lower()