diff options
Diffstat (limited to 'doc/src/sgml/ref/truncate.sgml')
| -rw-r--r-- | doc/src/sgml/ref/truncate.sgml | 38 |
1 files changed, 19 insertions, 19 deletions
diff --git a/doc/src/sgml/ref/truncate.sgml b/doc/src/sgml/ref/truncate.sgml index fef33155998..80abe675253 100644 --- a/doc/src/sgml/ref/truncate.sgml +++ b/doc/src/sgml/ref/truncate.sgml @@ -48,9 +48,9 @@ TRUNCATE [ TABLE ] [ ONLY ] <replaceable class="parameter">name</replaceable> [ <listitem> <para> The name (optionally schema-qualified) of a table to truncate. - If <literal>ONLY</> is specified before the table name, only that table - is truncated. If <literal>ONLY</> is not specified, the table and all - its descendant tables (if any) are truncated. Optionally, <literal>*</> + If <literal>ONLY</literal> is specified before the table name, only that table + is truncated. If <literal>ONLY</literal> is not specified, the table and all + its descendant tables (if any) are truncated. Optionally, <literal>*</literal> can be specified after the table name to explicitly indicate that descendant tables are included. </para> @@ -108,29 +108,29 @@ TRUNCATE [ TABLE ] [ ONLY ] <replaceable class="parameter">name</replaceable> [ </para> <para> - <command>TRUNCATE</> acquires an <literal>ACCESS EXCLUSIVE</> lock on each + <command>TRUNCATE</command> acquires an <literal>ACCESS EXCLUSIVE</literal> lock on each table it operates on, which blocks all other concurrent operations - on the table. When <literal>RESTART IDENTITY</> is specified, any + on the table. When <literal>RESTART IDENTITY</literal> is specified, any sequences that are to be restarted are likewise locked exclusively. If concurrent access to a table is required, then - the <command>DELETE</> command should be used instead. + the <command>DELETE</command> command should be used instead. </para> <para> - <command>TRUNCATE</> cannot be used on a table that has foreign-key + <command>TRUNCATE</command> cannot be used on a table that has foreign-key references from other tables, unless all such tables are also truncated in the same command. Checking validity in such cases would require table - scans, and the whole point is not to do one. The <literal>CASCADE</> + scans, and the whole point is not to do one. The <literal>CASCADE</literal> option can be used to automatically include all dependent tables — but be very careful when using this option, or else you might lose data you did not intend to! </para> <para> - <command>TRUNCATE</> will not fire any <literal>ON DELETE</literal> + <command>TRUNCATE</command> will not fire any <literal>ON DELETE</literal> triggers that might exist for the tables. But it will fire <literal>ON TRUNCATE</literal> triggers. - If <literal>ON TRUNCATE</> triggers are defined for any of + If <literal>ON TRUNCATE</literal> triggers are defined for any of the tables, then all <literal>BEFORE TRUNCATE</literal> triggers are fired before any truncation happens, and all <literal>AFTER TRUNCATE</literal> triggers are fired after the last truncation is @@ -141,36 +141,36 @@ TRUNCATE [ TABLE ] [ ONLY ] <replaceable class="parameter">name</replaceable> [ </para> <para> - <command>TRUNCATE</> is not MVCC-safe. After truncation, the table will + <command>TRUNCATE</command> is not MVCC-safe. After truncation, the table will appear empty to concurrent transactions, if they are using a snapshot taken before the truncation occurred. See <xref linkend="mvcc-caveats"> for more details. </para> <para> - <command>TRUNCATE</> is transaction-safe with respect to the data + <command>TRUNCATE</command> is transaction-safe with respect to the data in the tables: the truncation will be safely rolled back if the surrounding transaction does not commit. </para> <para> - When <literal>RESTART IDENTITY</> is specified, the implied - <command>ALTER SEQUENCE RESTART</> operations are also done + When <literal>RESTART IDENTITY</literal> is specified, the implied + <command>ALTER SEQUENCE RESTART</command> operations are also done transactionally; that is, they will be rolled back if the surrounding transaction does not commit. This is unlike the normal behavior of - <command>ALTER SEQUENCE RESTART</>. Be aware that if any additional + <command>ALTER SEQUENCE RESTART</command>. Be aware that if any additional sequence operations are done on the restarted sequences before the transaction rolls back, the effects of these operations on the sequences - will be rolled back, but not their effects on <function>currval()</>; - that is, after the transaction <function>currval()</> will continue to + will be rolled back, but not their effects on <function>currval()</function>; + that is, after the transaction <function>currval()</function> will continue to reflect the last sequence value obtained inside the failed transaction, even though the sequence itself may no longer be consistent with that. - This is similar to the usual behavior of <function>currval()</> after + This is similar to the usual behavior of <function>currval()</function> after a failed transaction. </para> <para> - <command>TRUNCATE</> is not currently supported for foreign tables. + <command>TRUNCATE</command> is not currently supported for foreign tables. This implies that if a specified table has any descendant tables that are foreign, the command will fail. </para> |