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1 | | -<!-- $Header: /cvsroot/pgsql/doc/src/sgml/wal.sgml,v 1.5 2001/03/16 05:44:33 tgl Exp $ --> |
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2 | 2 |
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3 | 3 | <chapter id="wal"> |
4 | 4 | <title>Write-Ahead Logging (<acronym>WAL</acronym>)</title> |
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243 | 243 | log (known as the redo record) it should start the REDO operation, |
244 | 244 | since any changes made to data files before that record are already |
245 | 245 | on disk. After a checkpoint has been made, any log segments written |
246 | | - before theredo record are removed, so checkpoints are used to free |
| 246 | + before theundo records are removed, so checkpoints are used to free |
247 | 247 | disk space in the <acronym>WAL</acronym> directory. (When |
248 | 248 | <acronym>WAL</acronym>-based <acronym>BAR</acronym> is implemented, |
249 | 249 | the log segments can be archived instead of just being removed.) |
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