diff options
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/storage.sgml | 26 |
1 files changed, 15 insertions, 11 deletions
diff --git a/doc/src/sgml/storage.sgml b/doc/src/sgml/storage.sgml index c4b38ddb6c8..46bb03432da 100644 --- a/doc/src/sgml/storage.sgml +++ b/doc/src/sgml/storage.sgml @@ -1,4 +1,4 @@ -<!-- $PostgreSQL: pgsql/doc/src/sgml/storage.sgml,v 1.32 2010/02/16 22:34:43 tgl Exp $ --> +<!-- $PostgreSQL: pgsql/doc/src/sgml/storage.sgml,v 1.33 2010/08/13 20:10:50 rhaas Exp $ --> <chapter id="storage"> @@ -133,16 +133,20 @@ there. </para> <para> -Each table and index is stored in a separate file, named after the table -or index's <firstterm>filenode</> number, which can be found in -<structname>pg_class</>.<structfield>relfilenode</>. In addition to the -main file (a/k/a main fork), each table and index has a <firstterm>free space -map</> (see <xref linkend="storage-fsm">), which stores information about free -space available in the relation. The free space map is stored in a file named -with the filenode number plus the suffix <literal>_fsm</>. Tables also have a -<firstterm>visibility map</>, stored in a fork with the suffix -<literal>_vm</>, to track which pages are known to have no dead tuples. -The visibility map is described further in <xref linkend="storage-vm">. +Each table and index is stored in a separate file. For ordinary relations, +these files are named after the table or index's <firstterm>filenode</> number, +which can be found in <structname>pg_class</>.<structfield>relfilenode</>. But +for temporary relations, the file name is of the form +<literal>t<replaceable>BBB</>_<replaceable>FFF</></>, where <replaceable>BBB</> +is the backend ID of the backend which created the file, and <replaceable>FFF</> +is the filenode number. In either case, in addition to the main file (a/k/a +main fork), each table and index has a <firstterm>free space map</> (see <xref +linkend="storage-fsm">), which stores information about free space available in +the relation. The free space map is stored in a file named with the filenode +number plus the suffix <literal>_fsm</>. Tables also have a +<firstterm>visibility map</>, stored in a fork with the suffix <literal>_vm</>, +to track which pages are known to have no dead tuples. The visibility map is +described further in <xref linkend="storage-vm">. </para> <caution> |