Split out pg_freespace views to one for relations and another for pages,
pg_freespacemap_relations and pg_freespacemap_pages. Mark Kirkwood
This commit is contained in:
Bruce Momjian
parent
028ec5cb0f
commit
136bea1540
@ -1,15 +1,17 @@
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Pg_freespacemap - Real time queries on the free space map (FSM).
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---------------
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This module consists of a C function 'pg_freespacemap()' that returns
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a set of records, and a view 'pg_freespacemap' to wrapper the function.
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This module consists of two C functions: 'pg_freespacemap_relations()' and
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'pg_freespacemap_pages()' that return a set of records, plus two views
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'pg_freespacemap_relations' and 'pg_freespacemap_pages' for more
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user-friendly access to the functions.
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The module provides the ability to examine the contents of the free space
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map, without having to restart or rebuild the server with additional
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debugging code.
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By default public access is REVOKED from both of these, just in case there
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are security issues lurking.
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By default public access is REVOKED from the functions and views, just in
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case there are security issues present in the code.
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Installation
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@ -22,7 +24,7 @@ Installation
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$ gmake install
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To register the functions:
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To register the functions and views:
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$ psql -d <database> -f pg_freespacemap.sql
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@ -30,38 +32,98 @@ Installation
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Notes
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-----
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The definition of the columns exposed in the view is:
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The definitions for the columns exposed in the views are:
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pg_freespacemap_relations
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Column | references | Description
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----------------+----------------------+------------------------------------
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reltablespace | pg_tablespace.oid | Tablespace oid of the relation.
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reldatabase | pg_database.oid | Database for the relation.
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relfilenode | pg_class.relfilenode | Refilenode of the relation.
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relblocknumber | | Offset of the page in the relation.
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bytes | | Free bytes in the block/page, or NULL
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avgrequest | | Moving average of free space
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| | requests.
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lastpagecount | | Count of pages examined for useful
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| | free space.
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nextpage | | page index (from 0) to start next
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| | search at.
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pg_freespacemap_pages
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Column | references | Description
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----------------+----------------------+------------------------------------
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reltablespace | pg_tablespace.oid | Tablespace oid of the relation.
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reldatabase | pg_database.oid | Database for the relation.
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relfilenode | pg_class.relfilenode | Refilenode of the relation.
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relblocknumber | | Page offset in the relation.
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bytes | | Free bytes in the page, or NULL
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| | for an index page (see below).
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There is one row for each page in the free space map.
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For pg_freespacemap_relations, there is one row for each relation in the free
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space map.
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Because the map is shared by all the databases, there are pages from
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relations not belonging to the current database.
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For pg_freespacemap_pages, there is one row for each page in the free space
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map.
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The free space map can contain pages for btree indexes if they were emptied
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by a vacuum process. The bytes field is set to NULL in this case.
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Because the map is shared by all the databases, there are relations and pages
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from relations not belonging to the current database.
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When the pg_freespacemap view is accessed, internal free space map locks are
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taken, and a copy of the map data is made for the view to display.
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This ensures that the view produces a consistent set of results, while not
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The view 'freespacemap_pages' can contain pages for btree indexes if they
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were emptied by a vacuum process. The bytes field is set to NULL in this case.
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When either of the views are accessed, internal free space map locks are
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taken, and a copy of the map data is made for them to display.
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This ensures that the views produce a consistent set of results, while not
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blocking normal activity longer than necessary. Nonetheless there
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could be some impact on database performance if this view is read often.
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could be some impact on database performance if they are read often.
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Sample output
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Sample output - pg_freespacemap_relations
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-------------
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regression=# \d pg_freespacemap
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View "public.pg_freespacemap"
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regression=# \d pg_freespacemap_relations
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View "public.pg_freespacemap_relations"
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Column | Type | Modifiers
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---------------+---------+-----------
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reltablespace | oid |
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reldatabase | oid |
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relfilenode | oid |
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avgrequest | bigint |
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lastpagecount | integer |
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nextpage | integer |
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View definition:
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SELECT p.reltablespace, p.reldatabase, p.relfilenode, p.avgrequest, p.lastpagecount, p.nextpage
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FROM pg_freespacemap_relations() p(reltablespace oid, reldatabase oid, relfilenode oid, avgrequest bigint, lastpagecount integer, nextpage integer);
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regression=# SELECT c.relname, r.avgrequest, r.lastpagecount, r.nextpage
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FROM pg_freespacemap_relations r INNER JOIN pg_class c
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ON c.relfilenode = r.relfilenode INNER JOIN pg_database d
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ON r.reldatabase = d.oid AND (d.datname = current_database())
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ORDER BY c.relname LIMIT 10;
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relname | avgrequest | lastpagecount | nextpage
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--------------+------------+---------------+----------
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a_star | 250 | 1 | 0
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abstime_tbl | 249 | 1 | 0
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aggtest | 250 | 1 | 0
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altinhoid | 250 | 1 | 0
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altstartwith | 250 | 1 | 0
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arrtest | 254 | 1 | 0
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b_star | 250 | 1 | 0
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box_tbl | 250 | 1 | 0
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bt_f8_heap | 92 | 1 | 0
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bt_i4_heap | 94 | 1 | 0
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(10 rows)
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regression=#
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Sample output - pg_freespacemap_pages
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-------------
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regression=# \d pg_freespacemap_pages;
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View "public.pg_freespacemap_pages"
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Column | Type | Modifiers
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----------------+---------+-----------
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reltablespace | oid |
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@ -71,28 +133,31 @@ Sample output
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bytes | integer |
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View definition:
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SELECT p.reltablespace, p.reldatabase, p.relfilenode, p.relblocknumber, p.bytes
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FROM pg_freespacemap() p(reltablespace oid, reldatabase oid, relfilenode oid, relblocknumber bigint, bytes integer);
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FROM pg_freespacemap_pages() p(reltablespace oid, reldatabase oid, relfilenode oid, relblocknumber bigint, bytes integer);
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regression=# SELECT c.relname, m.relblocknumber, m.bytes
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FROM pg_freespacemap m INNER JOIN pg_class c
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ON c.relfilenode = m.relfilenode LIMIT 10;
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regression=# SELECT c.relname, p.relblocknumber, p.bytes
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FROM pg_freespacemap_pages p INNER JOIN pg_class c
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ON c.relfilenode = p.relfilenode INNER JOIN pg_database d
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ON (p.reldatabase = d.oid AND d.datname = current_database())
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ORDER BY c.relname LIMIT 10;
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relname | relblocknumber | bytes
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------------------------+----------------+--------
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sql_features | 5 | 2696
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sql_implementation_info | 0 | 7104
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sql_languages | 0 | 8016
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sql_packages | 0 | 7376
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sql_sizing | 0 | 6032
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pg_authid | 0 | 7424
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pg_toast_2618 | 13 | 4588
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pg_toast_2618 | 12 | 1680
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pg_toast_2618 | 10 | 1436
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pg_toast_2618 | 7 | 1136
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--------------+----------------+-------
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a_star | 0 | 8040
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abstime_tbl | 0 | 7908
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aggtest | 0 | 8008
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altinhoid | 0 | 8128
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altstartwith | 0 | 8128
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arrtest | 0 | 7172
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b_star | 0 | 7976
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box_tbl | 0 | 7912
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bt_f8_heap | 54 | 7728
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bt_i4_heap | 49 | 8008
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(10 rows)
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regression=#
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Author
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------
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@ -1,9 +1,9 @@
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/*-------------------------------------------------------------------------
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*
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* pg_freespacemap.c
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* display some contents of the free space map.
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* display some contents of the free space relation and page maps.
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*
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* $PostgreSQL: pgsql/contrib/pg_freespacemap/pg_freespacemap.c,v 1.3 2006/04/26 22:41:18 momjian Exp $
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* $PostgreSQL: pgsql/contrib/pg_freespacemap/pg_freespacemap.c,v 1.4 2006/04/26 22:46:09 momjian Exp $
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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@ -13,18 +13,21 @@
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#include "utils/relcache.h"
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#define NUM_FREESPACE_PAGES_ELEM 5
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#define NUM_FREESPACE_RELATIONS_ELEM 6
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#if defined(WIN32) || defined(__CYGWIN__)
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/* Need DLLIMPORT for some things that are not so marked in main headers */
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extern DLLIMPORT int MaxFSMPages;
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extern DLLIMPORT int MaxFSMRelations;
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extern DLLIMPORT volatile uint32 InterruptHoldoffCount;
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#endif
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Datum pg_freespacemap(PG_FUNCTION_ARGS);
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Datum pg_freespacemap_pages(PG_FUNCTION_ARGS);
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Datum pg_freespacemap_relations(PG_FUNCTION_ARGS);
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/*
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* Record structure holding the to be exposed free space data.
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* Record structure holding the to be exposed free space page data.
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*/
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typedef struct
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{
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@ -40,7 +43,24 @@ typedef struct
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/*
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* Function context for data persisting over repeated calls.
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* Record structure holding the to be exposed free space relation data.
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*/
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typedef struct
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{
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uint32 reltablespace;
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uint32 reldatabase;
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uint32 relfilenode;
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int64 avgrequest;
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int lastpagecount;
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int nextpage;
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} FreeSpaceRelationsRec;
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/*
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* Function context for page data persisting over repeated calls.
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*/
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typedef struct
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{
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@ -53,11 +73,24 @@ typedef struct
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/*
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* Function returning data from the Free Space Map (FSM).
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* Function context for relation data persisting over repeated calls.
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*/
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PG_FUNCTION_INFO_V1(pg_freespacemap);
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typedef struct
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{
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AttInMetadata *attinmeta;
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FreeSpaceRelationsRec *record;
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char *values[NUM_FREESPACE_RELATIONS_ELEM];
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} FreeSpaceRelationsContext;
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/*
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* Function returning page data from the Free Space Map (FSM).
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*/
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PG_FUNCTION_INFO_V1(pg_freespacemap_pages);
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Datum
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pg_freespacemap(PG_FUNCTION_ARGS)
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pg_freespacemap_pages(PG_FUNCTION_ARGS)
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{
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FuncCallContext *funcctx;
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@ -250,3 +283,162 @@ pg_freespacemap(PG_FUNCTION_ARGS)
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SRF_RETURN_DONE(funcctx);
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}
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/*
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* Function returning relation data from the Free Space Map (FSM).
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*/
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PG_FUNCTION_INFO_V1(pg_freespacemap_relations);
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Datum
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pg_freespacemap_relations(PG_FUNCTION_ARGS)
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{
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FuncCallContext *funcctx;
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Datum result;
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MemoryContext oldcontext;
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FreeSpaceRelationsContext *fctx; /* User function context. */
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TupleDesc tupledesc;
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HeapTuple tuple;
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FSMHeader *FreeSpaceMap; /* FSM main structure. */
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FSMRelation *fsmrel; /* Individual relation. */
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if (SRF_IS_FIRSTCALL())
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{
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uint32 i;
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uint32 numRelations; /* Max no. of Relations in map. */
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/*
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* Get the free space map data structure.
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*/
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FreeSpaceMap = GetFreeSpaceMap();
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numRelations = MaxFSMRelations;
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funcctx = SRF_FIRSTCALL_INIT();
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/* Switch context when allocating stuff to be used in later calls */
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oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
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/* Construct a tuple to return. */
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tupledesc = CreateTemplateTupleDesc(NUM_FREESPACE_RELATIONS_ELEM, false);
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TupleDescInitEntry(tupledesc, (AttrNumber) 1, "reltablespace",
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OIDOID, -1, 0);
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TupleDescInitEntry(tupledesc, (AttrNumber) 2, "reldatabase",
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OIDOID, -1, 0);
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TupleDescInitEntry(tupledesc, (AttrNumber) 3, "relfilenode",
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OIDOID, -1, 0);
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TupleDescInitEntry(tupledesc, (AttrNumber) 4, "avgrequest",
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INT8OID, -1, 0);
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TupleDescInitEntry(tupledesc, (AttrNumber) 5, "lastpageCount",
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INT4OID, -1, 0);
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TupleDescInitEntry(tupledesc, (AttrNumber) 6, "nextpage",
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INT4OID, -1, 0);
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/* Generate attribute metadata needed later to produce tuples */
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funcctx->attinmeta = TupleDescGetAttInMetadata(tupledesc);
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/*
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* Create a function context for cross-call persistence and initialize
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* the counters.
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*/
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fctx = (FreeSpaceRelationsContext *) palloc(sizeof(FreeSpaceRelationsContext));
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funcctx->user_fctx = fctx;
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/* Set an upper bound on the calls */
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funcctx->max_calls = numRelations;
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/* Allocate numRelations worth of FreeSpaceRelationsRec records,
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* this is also an upper bound.
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*/
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fctx->record = (FreeSpaceRelationsRec *) palloc(sizeof(FreeSpaceRelationsRec) * numRelations);
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/* allocate the strings for tuple formation */
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fctx->values[0] = (char *) palloc(3 * sizeof(uint32) + 1);
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fctx->values[1] = (char *) palloc(3 * sizeof(uint32) + 1);
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fctx->values[2] = (char *) palloc(3 * sizeof(uint32) + 1);
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fctx->values[3] = (char *) palloc(3 * sizeof(int64) + 1);
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fctx->values[4] = (char *) palloc(3 * sizeof(int32) + 1);
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fctx->values[5] = (char *) palloc(3 * sizeof(int32) + 1);
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/* Return to original context when allocating transient memory */
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MemoryContextSwitchTo(oldcontext);
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/*
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* Lock free space map and scan though all the relations,
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*/
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LWLockAcquire(FreeSpaceLock, LW_EXCLUSIVE);
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i = 0;
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for (fsmrel = FreeSpaceMap->usageList; fsmrel; fsmrel = fsmrel->nextUsage)
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{
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fctx->record[i].reltablespace = fsmrel->key.spcNode;
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fctx->record[i].reldatabase = fsmrel->key.dbNode;
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fctx->record[i].relfilenode = fsmrel->key.relNode;
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fctx->record[i].avgrequest = (int64)fsmrel->avgRequest;
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fctx->record[i].lastpagecount = fsmrel->lastPageCount;
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fctx->record[i].nextpage = fsmrel->nextPage;
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i++;
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}
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/* Set the real no. of calls as we know it now! */
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funcctx->max_calls = i;
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/* Release free space map. */
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LWLockRelease(FreeSpaceLock);
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}
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funcctx = SRF_PERCALL_SETUP();
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/* Get the saved state */
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fctx = funcctx->user_fctx;
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if (funcctx->call_cntr < funcctx->max_calls)
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{
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uint32 i = funcctx->call_cntr;
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char *values[NUM_FREESPACE_RELATIONS_ELEM];
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int j;
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/*
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* Use a temporary values array, initially pointing to fctx->values,
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* so it can be reassigned w/o losing the storage for subsequent
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* calls.
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*/
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for (j = 0; j < NUM_FREESPACE_RELATIONS_ELEM; j++)
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{
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values[j] = fctx->values[j];
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}
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sprintf(values[0], "%u", fctx->record[i].reltablespace);
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sprintf(values[1], "%u", fctx->record[i].reldatabase);
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sprintf(values[2], "%u", fctx->record[i].relfilenode);
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sprintf(values[3], INT64_FORMAT, fctx->record[i].avgrequest);
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sprintf(values[4], "%d", fctx->record[i].lastpagecount);
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sprintf(values[5], "%d", fctx->record[i].nextpage);
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/* Build and return the tuple. */
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tuple = BuildTupleFromCStrings(funcctx->attinmeta, values);
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result = HeapTupleGetDatum(tuple);
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SRF_RETURN_NEXT(funcctx, result);
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}
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else
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SRF_RETURN_DONE(funcctx);
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}
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@ -2,18 +2,34 @@
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BEGIN;
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SET search_path = public;
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-- Register the function.
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CREATE OR REPLACE FUNCTION pg_freespacemap()
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-- Register the functions.
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CREATE OR REPLACE FUNCTION pg_freespacemap_pages()
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RETURNS SETOF RECORD
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AS 'MODULE_PATHNAME', 'pg_freespacemap'
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AS 'MODULE_PATHNAME', 'pg_freespacemap_pages'
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LANGUAGE C;
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-- Create a view for convenient access.
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CREATE VIEW pg_freespacemap AS
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SELECT P.* FROM pg_freespacemap() AS P
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CREATE OR REPLACE FUNCTION pg_freespacemap_relations()
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RETURNS SETOF RECORD
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AS 'MODULE_PATHNAME', 'pg_freespacemap_relations'
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LANGUAGE C;
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-- Create views for convenient access.
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CREATE VIEW pg_freespacemap_pages AS
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SELECT P.* FROM pg_freespacemap_pages() AS P
|
||||
(reltablespace oid, reldatabase oid, relfilenode oid, relblocknumber int8, bytes int4);
|
||||
|
||||
CREATE VIEW pg_freespacemap_relations AS
|
||||
SELECT P.* FROM pg_freespacemap_relations() AS P
|
||||
(reltablespace oid, reldatabase oid, relfilenode oid, avgrequest int8, lastpagecount integer, nextpage integer);
|
||||
|
||||
|
||||
-- Don't want these to be available at public.
|
||||
REVOKE ALL ON FUNCTION pg_freespacemap() FROM PUBLIC;
|
||||
REVOKE ALL ON pg_freespacemap FROM PUBLIC;
|
||||
REVOKE ALL ON FUNCTION pg_freespacemap_pages() FROM PUBLIC;
|
||||
REVOKE ALL ON pg_freespacemap_pages FROM PUBLIC;
|
||||
|
||||
REVOKE ALL ON FUNCTION pg_freespacemap_relations() FROM PUBLIC;
|
||||
REVOKE ALL ON pg_freespacemap_relations FROM PUBLIC;
|
||||
|
||||
COMMIT;
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user