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Standard English uses "may", "can", and "might" in different ways:
may - permission, "You may borrow my rake."
can - ability, "I can lift that log."
might - possibility, "It might rain today."
Unfortunately, in conversational English, their use is often mixed, as
in, "You may use this variable to do X", when in fact, "can" is a better
choice. Similarly, "It may crash" is better stated, "It might crash".
59 lines
1.6 KiB
Plaintext
59 lines
1.6 KiB
Plaintext
<!-- $PostgreSQL: pgsql/doc/src/sgml/ref/checkpoint.sgml,v 1.15 2007/01/31 23:26:02 momjian Exp $ -->
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<refentry id="sql-checkpoint">
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<refmeta>
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<refentrytitle id="sql-checkpoint-title">CHECKPOINT</refentrytitle>
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<refmiscinfo>SQL - Language Statements</refmiscinfo>
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</refmeta>
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<refnamediv>
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<refname>CHECKPOINT</refname>
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<refpurpose>force a transaction log checkpoint</refpurpose>
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</refnamediv>
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<indexterm zone="sql-checkpoint">
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<primary>CHECKPOINT</primary>
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</indexterm>
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<refsynopsisdiv>
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<synopsis>
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CHECKPOINT
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</synopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para>
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Write-Ahead Logging (WAL) puts a checkpoint in the transaction log
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every so often. (To adjust the automatic checkpoint interval, see
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the run-time configuration options <xref linkend="guc-checkpoint-segments">
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and <xref linkend="guc-checkpoint-timeout">.) The
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<command>CHECKPOINT</command> command forces an immediate
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checkpoint when the command is issued, without waiting for a
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scheduled checkpoint.
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</para>
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<para>
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A checkpoint is a point in the transaction log sequence at which
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all data files have been updated to reflect the information in the
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log. All data files will be flushed to disk. Refer to
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<xref linkend="wal"> for more information about the WAL system.
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</para>
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<para>
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Only superusers can call <command>CHECKPOINT</command>. The command is
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not intended for use during normal operation.
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</para>
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</refsect1>
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<refsect1>
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<title>Compatibility</title>
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<para>
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The <command>CHECKPOINT</command> command is a
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<productname>PostgreSQL</productname> language extension.
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</para>
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</refsect1>
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</refentry>
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