Remove spclocation field from pg_tablespace

Instead, add a function pg_tablespace_location(oid) used to return the same information, and do this by reading the symbolic link. Doing it this way makes it possible to relocate a tablespace when the database is down by simply changing the symbolic link.
2025-07-28 23:42:10 +03:00 · 2011-12-07 10:35:00 +01:00
parent c6e3ac11b6
commit 16d8e594ac
13 changed files with 114 additions and 40 deletions
--- a/src/backend/commands/tablespace.c
+++ b/src/backend/commands/tablespace.c
@ -314,8 +314,6 @@ CreateTableSpace(CreateTableSpaceStmt *stmt)
 		DirectFunctionCall1(namein, CStringGetDatum(stmt->tablespacename));
 	values[Anum_pg_tablespace_spcowner - 1] =
 		ObjectIdGetDatum(ownerId);
-	values[Anum_pg_tablespace_spclocation - 1] =
-		CStringGetTextDatum(location);
 	nulls[Anum_pg_tablespace_spcacl - 1] = true;
 	nulls[Anum_pg_tablespace_spcoptions - 1] = true;

--- a/src/backend/utils/adt/misc.c
+++ b/src/backend/utils/adt/misc.c
@ -18,6 +18,7 @@
 #include <signal.h>
 #include <dirent.h>
 #include <math.h>
+#include <unistd.h>

 #include "catalog/catalog.h"
 #include "catalog/pg_tablespace.h"
@ -261,6 +262,44 @@ pg_tablespace_databases(PG_FUNCTION_ARGS)
 }


+/*
+ * pg_tablespace_location - get location for a tablespace
+ */
+Datum
+pg_tablespace_location(PG_FUNCTION_ARGS)
+{
+	Oid		tablespaceOid = PG_GETARG_OID(0);
+	char	sourcepath[MAXPGPATH];
+	char	targetpath[MAXPGPATH];
+	int		rllen;
+
+	/*
+	 * Return empty string for our two default tablespace
+	 */
+	if (tablespaceOid == DEFAULTTABLESPACE_OID ||
+		tablespaceOid == GLOBALTABLESPACE_OID)
+		PG_RETURN_TEXT_P(cstring_to_text(""));
+
+#if defined(HAVE_READLINK) || defined(WIN32)
+	/*
+	 * Find the location of the tablespace by reading the symbolic link that is
+	 * in pg_tblspc/<oid>.
+	 */
+	snprintf(sourcepath, sizeof(sourcepath), "pg_tblspc/%u", tablespaceOid);
+	rllen =readlink(sourcepath, targetpath, sizeof(targetpath));
+	if (rllen < 0 || rllen >= sizeof(targetpath))
+		ereport(ERROR,
+				(errmsg("could not read symbolic link \"%s\": %m", sourcepath)));
+	targetpath[rllen] = '\0';
+
+	PG_RETURN_TEXT_P(cstring_to_text(targetpath));
+#else
+	ereport(ERROR,
+			(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+			 errmsg("tablespaces are not supported on this platform")));
+#endif
+}
+
 /*
 * pg_sleep - delay for N seconds
 */
--- a/src/bin/pg_dump/pg_dumpall.c
+++ b/src/bin/pg_dump/pg_dumpall.c
@ -997,7 +997,16 @@ dumpTablespaces(PGconn *conn)
 	 * Get all tablespaces except built-in ones (which we assume are named
 	 * pg_xxx)
 	 */
-	if (server_version >= 90000)
+	if (server_version >= 90200)
+		res = executeQuery(conn, "SELECT oid, spcname, "
+						 "pg_catalog.pg_get_userbyid(spcowner) AS spcowner, "
+						   "pg_catalog.pg_tablespace_location(oid), spcacl, "
+						   "array_to_string(spcoptions, ', '),"
+						"pg_catalog.shobj_description(oid, 'pg_tablespace') "
+						   "FROM pg_catalog.pg_tablespace "
+						   "WHERE spcname !~ '^pg_' "
+						   "ORDER BY 1");
+	else if (server_version >= 90000)
 		res = executeQuery(conn, "SELECT oid, spcname, "
 						 "pg_catalog.pg_get_userbyid(spcowner) AS spcowner, "
 						   "spclocation, spcacl, "
--- a/src/bin/psql/describe.c
+++ b/src/bin/psql/describe.c
@ -139,13 +139,22 @@ describeTablespaces(const char *pattern, bool verbose)

 	initPQExpBuffer(&buf);

-	printfPQExpBuffer(&buf,
-					  "SELECT spcname AS \"%s\",\n"
-					  "  pg_catalog.pg_get_userbyid(spcowner) AS \"%s\",\n"
-					  "  spclocation AS \"%s\"",
-					  gettext_noop("Name"),
-					  gettext_noop("Owner"),
-					  gettext_noop("Location"));
+	if (pset.sversion >= 90200)
+		printfPQExpBuffer(&buf,
+						  "SELECT spcname AS \"%s\",\n"
+						  "  pg_catalog.pg_get_userbyid(spcowner) AS \"%s\",\n"
+						  "  pg_catalog.pg_tablespace_location(oid) AS \"%s\"",
+						  gettext_noop("Name"),
+						  gettext_noop("Owner"),
+						  gettext_noop("Location"));
+	else
+		printfPQExpBuffer(&buf,
+						  "SELECT spcname AS \"%s\",\n"
+						  "  pg_catalog.pg_get_userbyid(spcowner) AS \"%s\",\n"
+						  "  spclocation AS \"%s\"",
+						  gettext_noop("Name"),
+						  gettext_noop("Owner"),
+						  gettext_noop("Location"));

 	if (verbose)
 	{
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@ -53,6 +53,6 @@
 */

 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	201112061
+#define CATALOG_VERSION_NO	201112071

 #endif
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@ -2686,6 +2686,9 @@ DESCR("statistics: reset collected statistics for a single table or index in the
 DATA(insert OID = 3777 (  pg_stat_reset_single_function_counters	PGNSP PGUID 12 1 0 0 0 f f f f f v 1 0 2278 "26" _null_ _null_ _null_ _null_	pg_stat_reset_single_function_counters _null_ _null_ _null_ ));
 DESCR("statistics: reset collected statistics for a single function in the current database");

+DATA(insert OID = 3778 ( pg_tablespace_location PGNSP PGUID 12 1 0 0 0 f f f t f s 1 0 25 "26" _null_ _null_ _null_ _null_ pg_tablespace_location _null_ _null_ _null_ ));
+DESCR("tablespace location");
+
 DATA(insert OID = 1946 (  encode						PGNSP PGUID 12 1 0 0 0 f f f t f i 2 0 25 "17 25" _null_ _null_ _null_ _null_ binary_encode _null_ _null_ _null_ ));
 DESCR("convert bytea value into some ascii-only text string");
 DATA(insert OID = 1947 (  decode						PGNSP PGUID 12 1 0 0 0 f f f t f i 2 0 17 "25 25" _null_ _null_ _null_ _null_ binary_decode _null_ _null_ _null_ ));
--- a/src/include/catalog/pg_tablespace.h
+++ b/src/include/catalog/pg_tablespace.h
@ -32,7 +32,6 @@ CATALOG(pg_tablespace,1213) BKI_SHARED_RELATION
 {
 	NameData	spcname;		/* tablespace name */
 	Oid			spcowner;		/* owner of tablespace */
-	text		spclocation;	/* physical location (VAR LENGTH) */
 	aclitem		spcacl[1];		/* access permissions (VAR LENGTH) */
 	text		spcoptions[1];	/* per-tablespace options */
 } FormData_pg_tablespace;
@ -49,15 +48,14 @@ typedef FormData_pg_tablespace *Form_pg_tablespace;
 * ----------------
 */

-#define Natts_pg_tablespace				5
+#define Natts_pg_tablespace				4
 #define Anum_pg_tablespace_spcname		1
 #define Anum_pg_tablespace_spcowner		2
-#define Anum_pg_tablespace_spclocation	3
-#define Anum_pg_tablespace_spcacl		4
-#define Anum_pg_tablespace_spcoptions	5
+#define Anum_pg_tablespace_spcacl		3
+#define Anum_pg_tablespace_spcoptions	4

-DATA(insert OID = 1663 ( pg_default PGUID "" _null_ _null_ ));
-DATA(insert OID = 1664 ( pg_global	PGUID "" _null_ _null_ ));
+DATA(insert OID = 1663 ( pg_default PGUID _null_ _null_ ));
+DATA(insert OID = 1664 ( pg_global	PGUID _null_ _null_ ));

 #define DEFAULTTABLESPACE_OID 1663
 #define GLOBALTABLESPACE_OID 1664
--- a/src/include/utils/builtins.h
+++ b/src/include/utils/builtins.h
@ -469,6 +469,7 @@ extern Datum pg_cancel_backend(PG_FUNCTION_ARGS);
 extern Datum pg_terminate_backend(PG_FUNCTION_ARGS);
 extern Datum pg_reload_conf(PG_FUNCTION_ARGS);
 extern Datum pg_tablespace_databases(PG_FUNCTION_ARGS);
+extern Datum pg_tablespace_location(PG_FUNCTION_ARGS);
 extern Datum pg_rotate_logfile(PG_FUNCTION_ARGS);
 extern Datum pg_sleep(PG_FUNCTION_ARGS);
 extern Datum pg_get_keywords(PG_FUNCTION_ARGS);