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Remove spclocation field from pg_tablespace

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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.
This commit is contained in:
Magnus Hagander
2011-12-07 10:35:00 +01:00
parent c6e3ac11b6
commit 16d8e594ac
13 changed files with 114 additions and 40 deletions
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39
src/backend/utils/adt/misc.c
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@ -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
*/