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| 1 | +<!-- $Header: /cvsroot/pgsql/doc/src/sgml/ref/start_transaction.sgml,v 1.1 2002/08/04 05:14:06 momjian Exp $ --> |
| 2 | +<refentry id="SQL-START-TRANSACTION"> |
| 3 | + <docinfo> |
| 4 | + <date>2002-07-26</date> |
| 5 | + </docinfo> |
| 6 | + |
| 7 | + <refmeta> |
| 8 | + <refentrytitle id="SQL-START-TRANSACTION-TITLE">START TRANSACTION</refentrytitle> |
| 9 | + <refmiscinfo>SQL - Language Statements</refmiscinfo> |
| 10 | + </refmeta> |
| 11 | + |
| 12 | + <refnamediv> |
| 13 | + <refname>START TRANSACTION</refname> |
| 14 | + <refpurpose>start a transaction block</refpurpose> |
| 15 | + </refnamediv> |
| 16 | + |
| 17 | + <refsynopsisdiv> |
| 18 | + <synopsis> |
| 19 | +START TRANSACTION [ ISOLATION LEVEL { READ COMMITTED | SERIALIZABLE } ] |
| 20 | + </synopsis> |
| 21 | + |
| 22 | + <refsect2 id="R2-SQL-START-TRANSACTION-1"> |
| 23 | + <refsect2info> |
| 24 | + <date>1998-09-27</date> |
| 25 | + </refsect2info> |
| 26 | + <title> |
| 27 | + Inputs |
| 28 | + </title> |
| 29 | + |
| 30 | + <para> |
| 31 | + None. |
| 32 | + </para> |
| 33 | + </refsect2> |
| 34 | + |
| 35 | + <refsect2 id="R2-SQL-START-TRANSACTION-2"> |
| 36 | + <refsect2info> |
| 37 | + <date>1998-09-27</date> |
| 38 | + </refsect2info> |
| 39 | + <title> |
| 40 | + Outputs |
| 41 | + </title> |
| 42 | + |
| 43 | + <para> |
| 44 | + |
| 45 | + <variablelist> |
| 46 | + <varlistentry> |
| 47 | + <term><computeroutput> |
| 48 | +START TRANSACTION |
| 49 | + </computeroutput></term> |
| 50 | + <listitem> |
| 51 | + <para> |
| 52 | + Message returned if successful. |
| 53 | + </para> |
| 54 | + </listitem> |
| 55 | + </varlistentry> |
| 56 | + <varlistentry> |
| 57 | + <term><computeroutput> |
| 58 | +WARNING: BEGIN: already a transaction in progress |
| 59 | + </computeroutput></term> |
| 60 | + <listitem> |
| 61 | + <para> |
| 62 | + If there is already a transaction in progress when the |
| 63 | + command is issued. |
| 64 | + </para> |
| 65 | + </listitem> |
| 66 | + </varlistentry> |
| 67 | + </variablelist> |
| 68 | + </para> |
| 69 | + </refsect2> |
| 70 | + </refsynopsisdiv> |
| 71 | + |
| 72 | + <refsect1> |
| 73 | + <title>Description</title> |
| 74 | + |
| 75 | + <para> |
| 76 | + This command begins a new transaction. If the isolation level is |
| 77 | + specified, the new transaction has that isolation level. In all other |
| 78 | + respects, the behavior of this command is identical to the |
| 79 | + <command>BEGIN</command>. |
| 80 | + </para> |
| 81 | + |
| 82 | + </refsect1> |
| 83 | + |
| 84 | + <refsect1> |
| 85 | + <title>Notes</title> |
| 86 | + |
| 87 | + <para> |
| 88 | + The isolation level of a transaction can also be set with the <xref |
| 89 | + linkend="sql-set-transaction" endterm="sql-set-transaction-title">. |
| 90 | + If no isolation level is specified, the level defaults to |
| 91 | + <option>READ COMMITTED</option>. |
| 92 | + </para> |
| 93 | + </refsect1> |
| 94 | + |
| 95 | + <refsect1 id="R1-SQL-START-TRANSACTION-3"> |
| 96 | + <title>Compatibility</title> |
| 97 | + |
| 98 | + <refsect2 id="R2-SQL-START-TRANSACTION-4"> |
| 99 | + <title>SQL99</title> |
| 100 | + |
| 101 | + <para> |
| 102 | + <option>SERIALIZABLE</option> is the default level in |
| 103 | + <acronym>SQL</acronym>. <productname>PostgreSQL</productname> |
| 104 | + does not provide the isolation levels <option>READ UNCOMMITTED</option> |
| 105 | + and <option>REPEATABLE READ</option>. Because of multiversion |
| 106 | + concurrency control, the <option>SERIALIZABLE</option> level is |
| 107 | + not truly serializable. See the <citetitle>User's Guide</citetitle> |
| 108 | + for details. |
| 109 | + </para> |
| 110 | + |
| 111 | + <para> |
| 112 | + In <acronym>SQL99</acronym> this statement can specify two other |
| 113 | + properties of the new transaction: whether the transaction is |
| 114 | + read-only and the size of the diagnostics area. Neither of these |
| 115 | + concepts are currently supported in |
| 116 | + <productname>PostgreSQL</productname>. |
| 117 | + </para> |
| 118 | + </refsect2> |
| 119 | + </refsect1> |
| 120 | +</refentry> |
| 121 | + |
| 122 | +<!-- Keep this comment at the end of the file |
| 123 | +Local variables: |
| 124 | +mode:sgml |
| 125 | +sgml-omittag:nil |
| 126 | +sgml-shorttag:t |
| 127 | +sgml-minimize-attributes:nil |
| 128 | +sgml-always-quote-attributes:t |
| 129 | +sgml-indent-step:1 |
| 130 | +sgml-indent-data:t |
| 131 | +sgml-parent-document:nil |
| 132 | +sgml-default-dtd-file:"../reference.ced" |
| 133 | +sgml-exposed-tags:nil |
| 134 | +sgml-local-catalogs:("/usr/lib/sgml/catalog") |
| 135 | +sgml-local-ecat-files:nil |
| 136 | +End: |
| 137 | +--> |
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