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1 | | -<!-- $PostgreSQL: pgsql/doc/src/sgml/storage.sgml,v 1.26 2008/10/06 14:13:17 heikki Exp $ --> |
| 1 | +<!-- $PostgreSQL: pgsql/doc/src/sgml/storage.sgml,v 1.27 2009/04/23 10:20:27 heikki Exp $ --> |
2 | 2 |
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3 | 3 | <chapter id="storage"> |
4 | 4 |
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@@ -134,7 +134,9 @@ or index's <firstterm>filenode</> number, which can be found in |
134 | 134 | main file (aka. main fork), a <firstterm>free space map</> (see |
135 | 135 | <xref linkend="storage-fsm">) that stores information about free space |
136 | 136 | available in the relation, is stored in a file named after the filenode |
137 | | -number, with the the <literal>_fsm</> suffix. |
| 137 | +number, with the <literal>_fsm</> suffix. Tables also have a visibility map |
| 138 | +fork, with the <literal>_vm</> suffix, to track which pages are known to have |
| 139 | +no dead tuples and therefore need no vacuuming. |
138 | 140 | </para> |
139 | 141 |
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140 | 142 | <caution> |
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