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Add a RESTART (without parameter) option to ALTER SEQUENCE, allowing a

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sequence to be reset to its original starting value.  This requires adding the
original start value to the set of parameters (columns) of a sequence object,
which is a user-visible change with potential compatibility implications;
it also forces initdb.

Also add hopefully-SQL-compatible RESTART/CONTINUE IDENTITY options to
TRUNCATE TABLE.  RESTART IDENTITY executes ALTER SEQUENCE RESTART for all
sequences "owned by" any of the truncated relations.  CONTINUE IDENTITY is
a no-op option.

Zoltan Boszormenyi
This commit is contained in:
Tom Lane
2008-05-16 23:36:05 +00:00
parent 8a2f5d221b
commit 10a3471bed
18 changed files with 513 additions and 106 deletions
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11
doc/src/sgml/ref/alter_sequence.sgml
View File

@ -1,5 +1,5 @@
<!--
$PostgreSQL: pgsql/doc/src/sgml/ref/alter_sequence.sgml,v 1.19 2007/10/25 18:54:03 tgl Exp $
$PostgreSQL: pgsql/doc/src/sgml/ref/alter_sequence.sgml,v 1.20 2008/05/16 23:36:04 tgl Exp $
PostgreSQL documentation
-->
@ -26,7 +26,7 @@ PostgreSQL documentation
<synopsis>
ALTER SEQUENCE <replaceable class="parameter">name</replaceable> [ INCREMENT [ BY ] <replaceable class="parameter">increment</replaceable> ]
[ MINVALUE <replaceable class="parameter">minvalue</replaceable> | NO MINVALUE ] [ MAXVALUE <replaceable class="parameter">maxvalue</replaceable> | NO MAXVALUE ]
[ RESTART [ WITH ] <replaceable class="parameter">start</replaceable> ] [ CACHE <replaceable class="parameter">cache</replaceable> ] [ [ NO ] CYCLE ]
[ RESTART [ [ WITH ] <replaceable class="parameter">start</replaceable> ] ] [ CACHE <replaceable class="parameter">cache</replaceable> ] [ [ NO ] CYCLE ]
[ OWNED BY { <replaceable class="parameter">table</replaceable>.<replaceable class="parameter">column</replaceable> | NONE } ]
ALTER SEQUENCE <replaceable class="parameter">name</replaceable> RENAME TO <replaceable class="parameter">new_name</replaceable>
ALTER SEQUENCE <replaceable class="parameter">name</replaceable> SET SCHEMA <replaceable class="parameter">new_schema</replaceable>
@ -112,12 +112,15 @@ ALTER SEQUENCE <replaceable class="parameter">name</replaceable> SET SCHEMA <rep
<term><replaceable class="parameter">start</replaceable></term>
<listitem>
<para>
The optional clause <literal>RESTART WITH <replaceable
class="parameter">start</replaceable></literal> changes the
The optional clause <literal>RESTART [ WITH <replaceable
class="parameter">start</replaceable> ]</literal> changes the
current value of the sequence. This is equivalent to calling the
<function>setval</> function with <literal>is_called</literal> =
<literal>false</>: the specified value will be returned by the
<emphasis>next</> call of <function>nextval</>.
Writing <literal>RESTART</> with no <replaceable
class="parameter">start</replaceable> value is equivalent to supplying
the start value used when the sequence was created.
</para>
</listitem>
</varlistentry>

60
doc/src/sgml/ref/truncate.sgml
View File

@ -1,5 +1,5 @@
<!--
$PostgreSQL: pgsql/doc/src/sgml/ref/truncate.sgml,v 1.25 2008/03/28 00:21:55 tgl Exp $
$PostgreSQL: pgsql/doc/src/sgml/ref/truncate.sgml,v 1.26 2008/05/16 23:36:04 tgl Exp $
PostgreSQL documentation
-->
@ -20,7 +20,8 @@ PostgreSQL documentation
<refsynopsisdiv>
<synopsis>
TRUNCATE [ TABLE ] <replaceable class="PARAMETER">name</replaceable> [, ...] [ CASCADE | RESTRICT ]
TRUNCATE [ TABLE ] <replaceable class="PARAMETER">name</replaceable> [, ... ]
[ RESTART IDENTITY | CONTINUE IDENTITY ] [ CASCADE | RESTRICT ]
</synopsis>
</refsynopsisdiv>
@ -50,6 +51,25 @@ TRUNCATE [ TABLE ] <replaceable class="PARAMETER">name</replaceable> [, ...] [ C
</listitem>
</varlistentry>
<varlistentry>
<term><literal>RESTART IDENTITY</literal></term>
<listitem>
<para>
Automatically restart sequences owned by columns of
the truncated table(s).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>CONTINUE IDENTITY</literal></term>
<listitem>
<para>
Do not change the values of sequences. This is the default.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>CASCADE</literal></term>
<listitem>
@ -66,7 +86,7 @@ TRUNCATE [ TABLE ] <replaceable class="PARAMETER">name</replaceable> [, ...] [ C
<listitem>
<para>
Refuse to truncate if any of the tables have foreign-key references
from tables that are not to be truncated. This is the default.
from tables that are not listed in the command. This is the default.
</para>
</listitem>
</varlistentry>
@ -119,11 +139,23 @@ TRUNCATE [ TABLE ] <replaceable class="PARAMETER">name</replaceable> [, ...] [ C
cause visible inconsistency between the contents of the truncated
table and other tables in the database.
</para>
</warning>
<para>
<command>TRUNCATE</> 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>
<warning>
<para>
<command>TRUNCATE</> is transaction-safe, however: the truncation
will be safely rolled back if the surrounding transaction does not
commit.
Any <command>ALTER SEQUENCE RESTART</> operations performed as a
consequence of using the <literal>RESTART IDENTITY</> option are
nontransactional and will not be rolled back. To minimize risk,
these operations are performed only after all the rest of
<command>TRUNCATE</>'s work is done. In practice this will only
be an issue if <command>TRUNCATE</> is performed inside a
transaction block that is aborted afterwards.
</para>
</warning>
</refsect1>
@ -132,13 +164,22 @@ TRUNCATE [ TABLE ] <replaceable class="PARAMETER">name</replaceable> [, ...] [ C
<title>Examples</title>
<para>
Truncate the tables <literal>bigtable</literal> and <literal>fattable</literal>:
Truncate the tables <literal>bigtable</literal> and
<literal>fattable</literal>:
<programlisting>
TRUNCATE bigtable, fattable;
</programlisting>
</para>
<para>
The same, and also reset any associated sequence generators:
<programlisting>
TRUNCATE bigtable, fattable RESTART IDENTITY;
</programlisting>
</para>
<para>
Truncate the table <literal>othertable</literal>, and cascade to any tables
that reference <literal>othertable</literal> via foreign-key
@ -154,7 +195,10 @@ TRUNCATE othertable CASCADE;
<title>Compatibility</title>
<para>
There is no <command>TRUNCATE</command> command in the SQL standard.
The draft SQL:2008 standard includes a <command>TRUNCATE</command> command,
but at this writing it is uncertain whether that will reach standardization
or be fully compatible with <productname>PostgreSQL</productname>'s
implementation.
</para>
</refsect1>
</refentry>