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Adjust /contrib/pg_freespace to show index free space as NULL (FSM only
tracks index pages, not free space on pages): 1/ Index free bytes set to NULL 2/ Comment added to the README briefly mentioning the index business 3/ Columns reordered more logically 4/ 'Blockid' column removed 5/ Free bytes column renamed to just 'bytes' instead of 'blockfreebytes' Mark Kirkwood
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@ -34,12 +34,12 @@ Notes
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Column | references | Description
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----------------+----------------------+------------------------------------
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blockid | | Id, 1.. max_fsm_pages
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relfilenode | pg_class.relfilenode | Refilenode of the relation.
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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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blockfreebytes | | Free bytes in the block/page.
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bytes | | Free bytes in the block/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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@ -47,6 +47,9 @@ Notes
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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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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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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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@ -58,34 +61,33 @@ Sample output
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-------------
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regression=# \d pg_freespacemap
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View "public.pg_freespacemap"
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View "public.pg_freespacemap"
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Column | Type | Modifiers
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---------------+---------+-----------
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blockid | integer |
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relfilenode | oid |
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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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relblocknumber | bigint |
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blockfreebytes | integer |
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bytes | integer |
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View definition:
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SELECT p.blockid, p.relfilenode, p.reltablespace, p.reldatabase, p.relblocknumber, p.blockfreebytes
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FROM pg_freespacemap() p(blockid integer, relfilenode oid, reltablespace oid, reldatabase oid, relblocknumber bigint, blockfreebytes integer);
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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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regression=# SELECT c.relname, m.relblocknumber, m.blockfreebytes
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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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relname | relblocknumber | blockfreebytes
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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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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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(10 rows)
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regression=#
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