98 lines
3.0 KiB
Plaintext
98 lines
3.0 KiB
Plaintext
<!--
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doc/src/sgml/ref/start_transaction.sgml
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PostgreSQL documentation
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-->
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<refentry id="sql-start-transaction">
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<indexterm zone="sql-start-transaction">
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<primary>START TRANSACTION</primary>
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</indexterm>
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<refmeta>
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<refentrytitle>START TRANSACTION</refentrytitle>
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<manvolnum>7</manvolnum>
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<refmiscinfo>SQL - Language Statements</refmiscinfo>
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</refmeta>
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<refnamediv>
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<refname>START TRANSACTION</refname>
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<refpurpose>start a transaction block</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<synopsis>
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START TRANSACTION [ <replaceable class="parameter">transaction_mode</replaceable> [, ...] ]
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<phrase>where <replaceable class="parameter">transaction_mode</replaceable> is one of:</phrase>
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ISOLATION LEVEL { SERIALIZABLE | REPEATABLE READ | READ COMMITTED | READ UNCOMMITTED }
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READ WRITE | READ ONLY
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[ NOT ] DEFERRABLE
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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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This command begins a new transaction block. If the isolation level,
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read/write mode, or deferrable mode is specified, the new transaction has those
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characteristics, as if <link linkend="sql-set-transaction"><command>SET TRANSACTION</command></link> was executed. This is the same
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as the <link linkend="sql-begin"><command>BEGIN</command></link> command.
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</para>
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</refsect1>
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<refsect1>
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<title>Parameters</title>
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<para>
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Refer to <xref linkend="sql-set-transaction"/> for information on the meaning
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of the parameters to this statement.
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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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In the standard, it is not necessary to issue <command>START TRANSACTION</command>
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to start a transaction block: any SQL command implicitly begins a block.
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<productname>PostgreSQL</productname>'s behavior can be seen as implicitly
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issuing a <command>COMMIT</command> after each command that does not
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follow <command>START TRANSACTION</command> (or <command>BEGIN</command>),
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and it is therefore often called <quote>autocommit</quote>.
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Other relational database systems might offer an autocommit feature
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as a convenience.
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</para>
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<para>
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The <literal>DEFERRABLE</literal>
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<replaceable class="parameter">transaction_mode</replaceable>
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is a <productname>PostgreSQL</productname> language extension.
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</para>
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<para>
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The SQL standard requires commas between successive <replaceable
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class="parameter">transaction_modes</replaceable>, but for historical
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reasons <productname>PostgreSQL</productname> allows the commas to be
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omitted.
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</para>
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<para>
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See also the compatibility section of <xref linkend="sql-set-transaction"/>.
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</para>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<simplelist type="inline">
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<member><xref linkend="sql-begin"/></member>
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<member><xref linkend="sql-commit"/></member>
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<member><xref linkend="sql-rollback"/></member>
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<member><xref linkend="sql-savepoint"/></member>
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<member><xref linkend="sql-set-transaction"/></member>
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</simplelist>
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</refsect1>
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</refentry>
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