1<!-- 2doc/src/sgml/ref/savepoint.sgml 3PostgreSQL documentation 4--> 5 6<refentry id="SQL-SAVEPOINT"> 7 <indexterm zone="sql-savepoint"> 8 <primary>SAVEPOINT</primary> 9 </indexterm> 10 11 <indexterm zone="sql-savepoint"> 12 <primary>savepoints</primary> 13 <secondary>defining</secondary> 14 </indexterm> 15 16 <refmeta> 17 <refentrytitle>SAVEPOINT</refentrytitle> 18 <manvolnum>7</manvolnum> 19 <refmiscinfo>SQL - Language Statements</refmiscinfo> 20 </refmeta> 21 22 <refnamediv> 23 <refname>SAVEPOINT</refname> 24 <refpurpose>define a new savepoint within the current transaction</refpurpose> 25 </refnamediv> 26 27 <refsynopsisdiv> 28<synopsis> 29SAVEPOINT <replaceable>savepoint_name</replaceable> 30</synopsis> 31 </refsynopsisdiv> 32 33 <refsect1> 34 <title>Description</title> 35 36 <para> 37 <command>SAVEPOINT</command> establishes a new savepoint within 38 the current transaction. 39 </para> 40 41 <para> 42 A savepoint is a special mark inside a transaction that allows all commands 43 that are executed after it was established to be rolled back, restoring 44 the transaction state to what it was at the time of the savepoint. 45 </para> 46 </refsect1> 47 48 <refsect1> 49 <title>Parameters</title> 50 51 <variablelist> 52 <varlistentry> 53 <term><replaceable>savepoint_name</replaceable></term> 54 <listitem> 55 <para> 56 The name to give to the new savepoint. 57 </para> 58 </listitem> 59 </varlistentry> 60 </variablelist> 61 </refsect1> 62 63 <refsect1> 64 <title>Notes</title> 65 66 <para> 67 Use <xref linkend="SQL-ROLLBACK-TO"> to 68 rollback to a savepoint. Use <xref linkend="SQL-RELEASE-SAVEPOINT"> 69 to destroy a savepoint, keeping 70 the effects of commands executed after it was established. 71 </para> 72 73 <para> 74 Savepoints can only be established when inside a transaction block. 75 There can be multiple savepoints defined within a transaction. 76 </para> 77 </refsect1> 78 79 <refsect1> 80 <title>Examples</title> 81 82 <para> 83 To establish a savepoint and later undo the effects of all commands executed 84 after it was established: 85<programlisting> 86BEGIN; 87 INSERT INTO table1 VALUES (1); 88 SAVEPOINT my_savepoint; 89 INSERT INTO table1 VALUES (2); 90 ROLLBACK TO SAVEPOINT my_savepoint; 91 INSERT INTO table1 VALUES (3); 92COMMIT; 93</programlisting> 94 The above transaction will insert the values 1 and 3, but not 2. 95 </para> 96 97 <para> 98 To establish and later destroy a savepoint: 99<programlisting> 100BEGIN; 101 INSERT INTO table1 VALUES (3); 102 SAVEPOINT my_savepoint; 103 INSERT INTO table1 VALUES (4); 104 RELEASE SAVEPOINT my_savepoint; 105COMMIT; 106</programlisting> 107 The above transaction will insert both 3 and 4. 108 </para> 109 </refsect1> 110 111 <refsect1> 112 <title>Compatibility</title> 113 114 <para> 115 SQL requires a savepoint to be destroyed automatically when another 116 savepoint with the same name is established. In 117 <productname>PostgreSQL</>, the old savepoint is kept, though only the more 118 recent one will be used when rolling back or releasing. (Releasing the 119 newer savepoint with <command>RELEASE SAVEPOINT</> will cause the older one 120 to again become accessible to <command>ROLLBACK TO SAVEPOINT</> and 121 <command>RELEASE SAVEPOINT</>.) Otherwise, <command>SAVEPOINT</command> is 122 fully SQL conforming. 123 </para> 124 </refsect1> 125 126 <refsect1> 127 <title>See Also</title> 128 129 <simplelist type="inline"> 130 <member><xref linkend="sql-begin"></member> 131 <member><xref linkend="sql-commit"></member> 132 <member><xref linkend="sql-release-savepoint"></member> 133 <member><xref linkend="sql-rollback"></member> 134 <member><xref linkend="sql-rollback-to"></member> 135 </simplelist> 136 </refsect1> 137</refentry> 138