Database-level collation version tracking

This adds to database objects the same version tracking that collation
objects have.  There is a new pg_database column datcollversion that
stores the version, a new function
pg_database_collation_actual_version() to get the version from the
operating system, and a new subcommand ALTER DATABASE ... REFRESH
COLLATION VERSION.

This was not originally added together with pg_collation.collversion,
since originally version tracking was only supported for ICU, and ICU
on a database-level is not currently supported.  But we now have
version tracking for glibc (since PG13), FreeBSD (since PG14), and
Windows (since PG13), so this is useful to have now.

Reviewed-by: Julien Rouhaud <rjuju123@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/f0ff3190-29a3-5b39-a179-fa32eee57db6%40enterprisedb.com

1 files changed, 34 insertions, 0 deletions

diff --git a/src/backend/utils/init/postinit.c b/src/backend/utils/init/postinit.c
index ca53912f151..02207a5b6f8 100644
--- a/src/backend/utils/init/postinit.c
+++ b/src/backend/utils/init/postinit.c
@@ -32,6 +32,7 @@
 #include "catalog/catalog.h"
 #include "catalog/namespace.h"
 #include "catalog/pg_authid.h"
+#include "catalog/pg_collation.h"
 #include "catalog/pg_database.h"
 #include "catalog/pg_db_role_setting.h"
 #include "catalog/pg_tablespace.h"
@@ -418,6 +419,39 @@ CheckMyDatabase(const char *name, bool am_superuser, bool override_allow_connect
 						   " which is not recognized by setlocale().", ctype),
 				 errhint("Recreate the database with another locale or install the missing locale.")));
 
+	/*
+	 * Check collation version.  See similar code in
+	 * pg_newlocale_from_collation().  Note that here we warn instead of error
+	 * in any case, so that we don't prevent connecting.
+	 */
+	datum = SysCacheGetAttr(DATABASEOID, tup, Anum_pg_database_datcollversion,
+							&isnull);
+	if (!isnull)
+	{
+		char	   *actual_versionstr;
+		char	   *collversionstr;
+
+		collversionstr = TextDatumGetCString(datum);
+
+		actual_versionstr = get_collation_actual_version(COLLPROVIDER_LIBC, collate);
+		if (!actual_versionstr)
+			ereport(WARNING,
+					(errmsg("database \"%s\" has no actual collation version, but a version was recorded",
+							name)));
+
+		if (strcmp(actual_versionstr, collversionstr) != 0)
+			ereport(WARNING,
+					(errmsg("database \"%s\" has a collation version mismatch",
+							name),
+					 errdetail("The database was created using collation version %s, "
+							   "but the operating system provides version %s.",
+							   collversionstr, actual_versionstr),
+					 errhint("Rebuild all objects in this database that use the default collation and run "
+							 "ALTER DATABASE %s REFRESH COLLATION VERSION, "
+							 "or build PostgreSQL with the right library version.",
+							 quote_identifier(name))));
+	}
+
 	/* Make the locale settings visible as GUC variables, too */
 	SetConfigOption("lc_collate", collate, PGC_INTERNAL, PGC_S_OVERRIDE);
 	SetConfigOption("lc_ctype", ctype, PGC_INTERNAL, PGC_S_OVERRIDE);