Special case C_COLLATION_OID in pg_newlocale_from_collation().

Allow pg_newlocale_from_collation(C_COLLATION_OID) to work even if
there's no catalog access, which some extensions expect.

Not known to be a bug without extensions involved, but backport to 18.

Also corrects an issue in master with dummy_c_locale (introduced in
commit 5a38104b36) where deterministic was not set. That wasn't a bug,
but could have been if that structure was used more widely.

Reported-by: Alexander Kukushkin <cyberdemn@gmail.com>
Reviewed-by: Alexander Kukushkin <cyberdemn@gmail.com>
Discussion: https://postgr.es/m/CAFh8B=nj966ECv5vi_u3RYij12v0j-7NPZCXLYzNwOQp9AcPWQ@mail.gmail.com
Backpatch-through: 18

diff --git a/src/backend/regex/regc_pg_locale.c b/src/backend/regex/regc_pg_locale.c
index e0c892db713a4e43faf7564fe0491eab7b33303d..4698f110a0c21a98e293e7aa367396af4a53e5b8 100644 (file)
--- a/src/backend/regex/regc_pg_locale.c
+++ b/src/backend/regex/regc_pg_locale.c
@@ -23,11 +23,6 @@
 
 static pg_locale_t pg_regex_locale;
 
-static struct pg_locale_struct dummy_c_locale = {
-       .collate_is_c = true,
-       .ctype_is_c = true,
-};
-
 
 /*
  * pg_set_regex_collation: set collation for these functions to obey
@@ -53,33 +48,12 @@ pg_set_regex_collation(Oid collation)
                                 errhint("Use the COLLATE clause to set the collation explicitly.")));
        }
 
-       if (collation == C_COLLATION_OID)
-       {
-               /*
-                * Some callers expect regexes to work for C_COLLATION_OID before
-                * catalog access is available, so we can't call
-                * pg_newlocale_from_collation().
-                */
-               locale = &dummy_c_locale;
-       }
-       else
-       {
-               locale = pg_newlocale_from_collation(collation);
-
-               if (!locale->deterministic)
-                       ereport(ERROR,
-                                       (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-                                        errmsg("nondeterministic collations are not supported for regular expressions")));
+       locale = pg_newlocale_from_collation(collation);
 
-               if (locale->ctype_is_c)
-               {
-                       /*
-                        * C/POSIX collations use this path regardless of database
-                        * encoding
-                        */
-                       locale = &dummy_c_locale;
-               }
-       }
+       if (!locale->deterministic)
+               ereport(ERROR,
+                               (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+                                errmsg("nondeterministic collations are not supported for regular expressions")));
 
        pg_regex_locale = locale;
 }

diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c
index 67299c55ed8a84e16f2db0964b17cafb38f76dde..b14c7837938128a34a6adea0e92c26cfca688189 100644 (file)
--- a/src/backend/utils/adt/pg_locale.c
+++ b/src/backend/utils/adt/pg_locale.c
@@ -106,6 +106,12 @@ static pg_locale_t default_locale = NULL;
 static bool CurrentLocaleConvValid = false;
 static bool CurrentLCTimeValid = false;
 
+static struct pg_locale_struct c_locale = {
+       .deterministic = true,
+       .collate_is_c = true,
+       .ctype_is_c = true,
+};
+
 /* Cache for collation-related knowledge */
 
 typedef struct
@@ -1185,6 +1191,13 @@ pg_newlocale_from_collation(Oid collid)
        if (collid == DEFAULT_COLLATION_OID)
                return default_locale;
 
+       /*
+        * Some callers expect C_COLLATION_OID to succeed even without catalog
+        * access.
+        */
+       if (collid == C_COLLATION_OID)
+               return &c_locale;
+
        if (!OidIsValid(collid))
                elog(ERROR, "cache lookup failed for collation %u", collid);