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| 1 | +<!-- $Header: /cvsroot/pgsql/doc/src/sgml/wal.sgml,v 1.18 2002/08/30 16:53:34 momjian Exp $ --> |
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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302 | 302 | </para> |
303 | 303 |
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304 | 304 | <para> |
305 | | -The number of16MB segmentfileswillalways be at least |
306 | | -1, and will normally not exceed <varname>CHECKPOINT_SEGMENTS</varname>) |
307 | | - + 1.This may be used to estimate space requirements for WAL. |
308 | | - Ordinarily, when old log segment files are no longer needed, |
| 305 | +There will be at least one16MB segmentfile, andwillnormally |
| 306 | +not be more than <varname>CHECKPOINT_SEGMENTS</varname>) |
| 307 | + + 1 files.You can use this to estimate space requirements for |
| 308 | +WAL.Ordinarily, when old log segment files are no longer needed, |
309 | 309 | they are recycled (renamed to become the next sequential future |
310 | 310 | segments). If, due to a short-term peak of log output rate, there |
311 | 311 | are more than <varname>CHECKPOINT_SEGMENTS</varname>) + 1 segment files, |
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