Helle,
I've added visibility map information to pg_freespace for my
utility.
This looks like this,
postgres=# select * from pg_freespace('t'::regclass);
blkno | avail | all_visible
-------+-------+-------------
0 | 7424 | t
1 | 7424 | t
2 | 7424 | t
3 | 7424 | t
4 | 7424 | t
5 | 7424 | t
6 | 7424 | t
7 | 7424 | t
...
What do you think about this?
regards,
--
Kyotaro Horiguchi
NTT Open Source Software Center
diff --git a/contrib/pg_freespacemap/pg_freespacemap--1.0.sql b/contrib/pg_freespacemap/pg_freespacemap--1.0.sql
index 2adb52a..e38b466 100644
--- a/contrib/pg_freespacemap/pg_freespacemap--1.0.sql
+++ b/contrib/pg_freespacemap/pg_freespacemap--1.0.sql
@@ -9,12 +9,17 @@ RETURNS int2
AS 'MODULE_PATHNAME', 'pg_freespace'
LANGUAGE C STRICT;
+CREATE FUNCTION pg_is_all_visible(regclass, bigint)
+RETURNS bool
+AS 'MODULE_PATHNAME', 'pg_is_all_visible'
+LANGUAGE C STRICT;
+
-- pg_freespace shows the recorded space avail at each block in a relation
CREATE FUNCTION
- pg_freespace(rel regclass, blkno OUT bigint, avail OUT int2)
+ pg_freespace(rel regclass, blkno OUT bigint, avail OUT int2, all_visible OUT bool)
RETURNS SETOF RECORD
AS $$
- SELECT blkno, pg_freespace($1, blkno) AS avail
+ SELECT blkno, pg_freespace($1, blkno) AS avail, pg_is_all_visible($1, blkno) AS all_visible
FROM generate_series(0, pg_relation_size($1) / current_setting('block_size')::bigint - 1) AS blkno;
$$
LANGUAGE SQL;
diff --git a/contrib/pg_freespacemap/pg_freespacemap.c b/contrib/pg_freespacemap/pg_freespacemap.c
index f6f7d2e..de4eff7 100644
--- a/contrib/pg_freespacemap/pg_freespacemap.c
+++ b/contrib/pg_freespacemap/pg_freespacemap.c
@@ -10,17 +10,20 @@
#include "funcapi.h"
#include "storage/freespace.h"
+#include "access/visibilitymap.h"
PG_MODULE_MAGIC;
Datum pg_freespace(PG_FUNCTION_ARGS);
+Datum pg_is_all_visible(PG_FUNCTION_ARGS);
/*
* Returns the amount of free space on a given page, according to the
* free space map.
*/
PG_FUNCTION_INFO_V1(pg_freespace);
+PG_FUNCTION_INFO_V1(pg_is_all_visible);
Datum
pg_freespace(PG_FUNCTION_ARGS)
@@ -38,7 +41,32 @@ pg_freespace(PG_FUNCTION_ARGS)
errmsg("invalid block number")));
freespace = GetRecordedFreeSpace(rel, blkno);
-
relation_close(rel, AccessShareLock);
PG_RETURN_INT16(freespace);
}
+
+Datum
+pg_is_all_visible(PG_FUNCTION_ARGS)
+{
+ Oid relid = PG_GETARG_OID(0);
+ int64 blkno = PG_GETARG_INT64(1);
+ Buffer vmbuffer = InvalidBuffer;
+ int all_visible;
+ Relation rel;
+
+ rel = relation_open(relid, AccessShareLock);
+
+ if (blkno < 0 || blkno > MaxBlockNumber)
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("invalid block number")));
+
+ all_visible = visibilitymap_test(rel, blkno, &vmbuffer);
+ if (vmbuffer != InvalidBuffer)
+ {
+ ReleaseBuffer(vmbuffer);
+ vmbuffer = InvalidBuffer;
+ }
+ relation_close(rel, AccessShareLock);
+ PG_RETURN_BOOL(all_visible);
+}
diff --git a/contrib/pg_freespacemap/pg_freespacemap.control b/contrib/pg_freespacemap/pg_freespacemap.control
index 34b695f..395350a 100644
--- a/contrib/pg_freespacemap/pg_freespacemap.control
+++ b/contrib/pg_freespacemap/pg_freespacemap.control
@@ -1,5 +1,5 @@
# pg_freespacemap extension
-comment = 'examine the free space map (FSM)'
+comment = 'examine the free space map (FSM) and visibility map (VM)'
default_version = '1.0'
module_pathname = '$libdir/pg_freespacemap'
relocatable = true
--
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