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Postgres FD Implementation
Commit 4f51368b authored by Bruce Momjian's avatar Bruce Momjian
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Add routines to dbsize to return the index size and total relation size. 

Improve documentation.

Ed L.
parent f5533957
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contrib/dbsize/README.dbsize
View file @ 4f51368b
This module contains several functions that report the size of a given
database object:
This module contains several functions that report the on-disk size of a
given database object in bytes:
int8 database_size(name)
int8 relation_size(text)
int8 indexes_size(text)
int8 total_relation_size(text)
int8 pg_database_size(oid)
int8 pg_relation_size(oid)
......@@ -10,42 +12,104 @@ database object:
text pg_size_pretty(int8)
The first two functions:
setof record relation_size_components(text)
The first four functions take the name of the object (possibly
schema-qualified for the latter three) and returns the size of the
on-disk files in bytes.
SELECT database_size('template1');
SELECT relation_size('pg_class');
SELECT indexes_size('pg_class');
SELECT total_relation_size('pg_class');
take the name of the object (possibly schema-qualified, for relation_size),
while these functions take object OIDs:
These functions take object OIDs:
SELECT pg_database_size(1); -- template1 database
SELECT pg_relation_size(1259); -- pg_class table size
SELECT pg_tablespace_size(1663); -- pg_default tablespace
The indexes_size() function returns the total size of the indices for a
relation, including any toasted indices.
The total_relation_size() function returns the total size of the relation,
all its indices, and any toasted data.
Please note that relation_size and pg_relation_size report only the size of
the selected relation itself; any subsidiary indexes or toast tables are not
counted. To obtain the total size of a table including all helper files
you'd have to do something like:
SELECT *,
pg_size_pretty(tablesize+indexsize+toastsize+toastindexsize) AS totalsize
FROM
(SELECT pg_relation_size(cl.oid) AS tablesize,
COALESCE((SELECT SUM(pg_relation_size(indexrelid))::bigint
FROM pg_index WHERE cl.oid=indrelid), 0) AS indexsize,
CASE WHEN reltoastrelid=0 THEN 0
ELSE pg_relation_size(reltoastrelid)
END AS toastsize,
CASE WHEN reltoastrelid=0 THEN 0
ELSE pg_relation_size((SELECT reltoastidxid FROM pg_class ct
WHERE ct.oid = cl.reltoastrelid))
END AS toastindexsize
FROM pg_class cl
WHERE relname = 'foo') ss;
This sample query utilizes the helper function pg_size_pretty(int8),
which formats the number of bytes into a convenient string using KB, MB,
GB. It is also contained in this module.
the selected relation itself; any related indexes or toast tables are not
counted. To obtain the total size of a table including all indices and
toasted data, use total_relation_size().
The last function, relation_size_components(), returns a set of rows
showing the sizes of the component relations constituting the input
relation.
Examples
========
I've loaded the following table with a little less than 3 MB of data for
illustration:
create table fat ( id serial, data varchar );
create index fat_uidx on fat (id);
create index fat_idx on fat (data);
You can retrieve a rowset containing constituent sizes as follows:
# SELECT relation_size_components('fat');
relation_size_components
----------------------------------------------------
(2088960,65536,2891776,fat,r,59383,59383)
(32768,704512,737280,pg_toast_59383,t,59386,59386)
(0,32768,32768,pg_toast_59383_index,i,59388,59388)
(0,2039808,2039808,fat_idx,i,59389,59389)
(0,49152,49152,fat_uidx,i,59911,59911)
(5 rows)
To see a more readable output of the rowset:
SELECT *
FROM relation_size_components('fat') AS (idxsize BIGINT,
datasize BIGINT,
totalsize BIGINT,
relname NAME,
kind "char",
relid OID,
node OID)
ORDER BY totalsize;
idxsize | datasize | totalsize | relname | kind | relid | node
---------+----------+-----------+----------------------+------+-------+-------
0 | 32768 | 32768 | pg_toast_59383_index | i | 59388 | 59388
0 | 49152 | 49152 | fat_uidx | i | 59911 | 59911
32768 | 704512 | 737280 | pg_toast_59383 | t | 59386 | 59386
0 | 2039808 | 2039808 | fat_idx | i | 59389 | 59389
2088960 | 65536 | 2891776 | fat | r | 59383 | 59383
(5 rows)
To see the sum total size of a relation:
# select total_relation_size('fat');
total_relation_size
-------------------------
2891776
(1 row)
To see just the size of the uncompressed relation data:
# select relation_size('fat');
relation_size
---------------
65536
(1 row)
To see the size of all related indices:
# select indexes_size('fat');
indexes_size
--------------
2088960
(1 row)
To install, just run make; make install. Then load the functions
into any database using dbsize.sql.
contrib/dbsize/dbsize.sql.in
View file @ 4f51368b
......@@ -21,3 +21,112 @@ CREATE FUNCTION pg_relation_size(oid) RETURNS bigint
CREATE FUNCTION pg_size_pretty(bigint) RETURNS text
AS 'MODULE_PATHNAME', 'pg_size_pretty'
LANGUAGE C STRICT;
CREATE FUNCTION total_relation_size (text) RETURNS bigint AS '
SELECT pg_relation_size(r.oid)
+ COALESCE(pg_relation_size(t.oid), 0)::bigint
+ COALESCE(pg_relation_size(ti.oid), 0)::bigint
+ COALESCE(SUM(pg_relation_size(i.indexrelid)), 0)::bigint
+ COALESCE(SUM(pg_relation_size(it.oid)), 0)::bigint
+ COALESCE(SUM(pg_relation_size(iti.oid)), 0)::bigint AS bytes
FROM pg_class r
LEFT JOIN pg_class t ON (r.reltoastrelid = t.oid)
LEFT JOIN pg_class ti ON (t.reltoastidxid = ti.oid)
LEFT JOIN pg_index i ON (r.oid = i.indrelid)
LEFT JOIN pg_class ir ON (ir.oid = i.indexrelid)
LEFT JOIN pg_class it ON (ir.reltoastrelid = it.oid)
LEFT JOIN pg_class iti ON (it.reltoastidxid = iti.oid)
WHERE r.relname = \$1
GROUP BY r.oid, t.oid, ti.oid
' LANGUAGE SQL;
CREATE FUNCTION indexes_size (text) RETURNS bigint
AS '
SELECT COALESCE(SUM(pg_relation_size(ir.oid)), 0)::bigint
+ COALESCE(SUM(pg_relation_size(it.oid)), 0)::bigint
+ COALESCE(SUM(pg_relation_size(iti.oid)), 0)::bigint AS bytes
FROM pg_class r
LEFT JOIN pg_index i ON (r.oid = i.indrelid)
LEFT JOIN pg_class ir ON (ir.oid = i.indexrelid)
LEFT JOIN pg_class it ON (ir.reltoastrelid = it.oid)
LEFT JOIN pg_class iti ON (it.reltoastidxid = iti.oid)
WHERE r.relname = \$1
' LANGUAGE SQL;
CREATE FUNCTION relation_size_components (text) RETURNS SETOF RECORD
AS '
-- relation size
SELECT indexes_size(r.relname) AS indexes_size,
relation_size(r.relname) AS data_size,
total_relation_size(r.relname) AS total_size,
r.relname, r.relkind, r.oid AS relid, r.relfilenode
FROM pg_class r
WHERE r.relname = \$1
UNION ALL
-- relation toast size
SELECT indexes_size(toast.relname) AS indexes_size,
relation_size(''pg_toast.''||toast.relname) AS data_size,
total_relation_size(toast.relname) AS total_size,
toast.relname, toast.relkind, toast.oid AS relid, toast.relfilenode
FROM pg_class r, pg_class toast
WHERE r.reltoastrelid = toast.oid
AND r.relname = \$1
UNION ALL
-- relation toast index size
SELECT indexes_size(toastidxr.relname) AS indexes_size,
relation_size(''pg_toast.''||toastidxr.relname) AS data_size,
total_relation_size(toastidxr.relname) AS total_size,
toastidxr.relname, toastidxr.relkind,
toastidxr.oid AS relid, toastidxr.relfilenode
FROM pg_class r, pg_index toastidx, pg_class toastidxr
WHERE r.relname = \$1
AND r.reltoastrelid = toastidx.indrelid
AND toastidx.indexrelid = toastidxr.oid
UNION ALL
-- relation indices size
SELECT indexes_size(idxr.relname) AS indexes_size,
relation_size(idxr.relname) AS data_size,
total_relation_size(idxr.relname) AS total_size,
idxr.relname, idxr.relkind, idxr.oid AS relid, idxr.relfilenode
FROM pg_class r, pg_class idxr, pg_index idx
WHERE r.relname = \$1
AND r.oid = idx.indrelid
AND idx.indexrelid = idxr.oid
UNION ALL
-- relation indices toast size
SELECT indexes_size(idxtoastr.relname) AS indexes_size,
relation_size(''pg_toast.''||idxtoastr.relname) AS data_size,
total_relation_size(idxtoastr.relname) AS total_size,
idxtoastr.relname, idxtoastr.relkind, idxtoastr.oid AS relid,
idxtoastr.relfilenode
FROM pg_class r, pg_class idxr, pg_index idx, pg_class idxtoastr
WHERE r.relname = \$1
AND r.oid = idx.indrelid
AND idx.indexrelid = idxr.oid
AND idxr.reltoastrelid = idxtoastr.oid
UNION ALL
-- relation indices toast index size
SELECT indexes_size(idxtoastidxr.relname) AS indexes_size,
relation_size(''pg_toast.''||idxtoastidxr.relname) AS data_size,
total_relation_size(idxtoastidxr.relname) AS total_size,
idxtoastidxr.relname, idxtoastidxr.relkind,
idxtoastidxr.oid AS relid, idxtoastidxr.relfilenode
FROM pg_class r, pg_class idxr, pg_index idx, pg_class idxtoast,
pg_class idxtoastidxr
WHERE r.relname = \$1
AND r.oid = idx.indrelid
AND idx.indexrelid = idxr.oid
AND idxr.reltoastrelid = idxtoast.oid
AND idxtoast.reltoastrelid = idxtoastidxr.oid
' LANGUAGE SQL;
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