Allow NULL version for individual collations.
Remove the documented restriction that collation providers must either
return NULL for all collations or non-NULL for all collations.
Use NULL for glibc collations like "C.UTF-8", which might otherwise lead
future proposed commits to force unnecessary index rebuilds.
Discussion:
@@ -1505,10 +1505,6 @@ pg_newlocale_from_collation(Oid collid)
/*
* Get provider-specific collation version string for the given collation from
* the operating system/library.
- *
- * A particular provider must always either return a non-NULL string or return
- * NULL (if it doesn't support versions). It must not return NULL for some
- * collcollate and not NULL for others.
*/
char *
get_collation_actual_version(char collprovider, const char *collcollate)
@@ -1540,6 +1536,23 @@ get_collation_actual_version(char collprovider, const char *collcollate)
if (collprovider == COLLPROVIDER_LIBC)
{
#if defined(__GLIBC__)
+ char *copy = pstrdup(collcollate);
+ char *copy_suffix = strstr(copy, ".");
+ bool need_version = true;
+
+ /*
+ * Check for names like C.UTF-8 by chopping off the encoding suffix on
+ * our temporary copy, so we can skip the version.
+ */
+ if (copy_suffix)
+ *copy_suffix = '\0';
+ if (pg_strcasecmp("c", copy) == 0 ||
+ pg_strcasecmp("posix", copy) == 0)
+ need_version = false;
+ pfree(copy);
+ if (!need_version)
+ return NULL;
+
/* Use the glibc version because we don't have anything better. */
collversion = pstrdup(gnu_get_libc_version());
#endif
