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Allow ALTER SEQUENCE START WITH to change the recorded start_value of a

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sequence.  This seems an obvious extension to the recent patch, and it
makes the code noticeably cleaner and more orthogonal.
REL8_5_ALPHA1_BRANCH
Tom Lane 18 years ago
parent 3951fae51d
commit caede71b44
2 changed files with 59 additions and 50 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 29
      doc/src/sgml/ref/alter_sequence.sgml
  2. 80
      src/backend/commands/sequence.c

29
doc/src/sgml/ref/alter_sequence.sgml
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@ -1,5 +1,5 @@
<!--
$PostgreSQL: pgsql/doc/src/sgml/ref/alter_sequence.sgml,v 1.20 2008/05/16 23:36:04 tgl Exp $
$PostgreSQL: pgsql/doc/src/sgml/ref/alter_sequence.sgml,v 1.21 2008/05/17 01:20:39 tgl Exp $
PostgreSQL documentation
-->
@ -26,7 +26,9 @@ 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 ]
[ START [ WITH ] <replaceable class="parameter">start</replaceable> ]
[ RESTART [ [ WITH ] <replaceable class="parameter">restart</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>
@ -110,17 +112,31 @@ ALTER SEQUENCE <replaceable class="parameter">name</replaceable> SET SCHEMA <rep
<varlistentry>
<term><replaceable class="parameter">start</replaceable></term>
<listitem>
<para>
The optional clause <literal>START WITH <replaceable
class="parameter">start</replaceable></literal> changes the
recorded start value of the sequence. This has no effect on the
<emphasis>current</> sequence value; it simply sets the value
that future <command>ALTER SEQUENCE RESTART</> commands will use.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">restart</replaceable></term>
<listitem>
<para>
The optional clause <literal>RESTART [ WITH <replaceable
class="parameter">start</replaceable> ]</literal> changes the
class="parameter">restart</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.
class="parameter">restart</> value is equivalent to supplying
the start value that was recorded by <command>CREATE SEQUENCE</>
or last set by <command>ALTER SEQUENCE START WITH</>.
</para>
</listitem>
</varlistentry>
@ -261,7 +277,8 @@ ALTER SEQUENCE serial RESTART WITH 105;
<para>
<command>ALTER SEQUENCE</command> conforms to the <acronym>SQL</acronym>
standard, except for the <literal>OWNED BY</>, <literal>RENAME</>, and
standard, except for the <literal>START WITH</>,
<literal>OWNED BY</>, <literal>RENAME</>, and
<literal>SET SCHEMA</literal> clauses, which are
<productname>PostgreSQL</productname> extensions.
</para>

80
src/backend/commands/sequence.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/sequence.c,v 1.151 2008/05/16 23:36:04 tgl Exp $
* $PostgreSQL: pgsql/src/backend/commands/sequence.c,v 1.152 2008/05/17 01:20:39 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -91,7 +91,7 @@ static Relation open_share_lock(SeqTable seq);
static void init_sequence(Oid relid, SeqTable *p_elm, Relation *p_rel);
static Form_pg_sequence read_info(SeqTable elm, Relation rel, Buffer *buf);
static void init_params(List *options, bool isInit,
Form_pg_sequence new, Form_pg_sequence old, List **owned_by);
Form_pg_sequence new, List **owned_by);
static void do_setval(Oid relid, int64 next, bool iscalled);
static void process_owned_by(Relation seqrel, List *owned_by);
@ -119,7 +119,7 @@ DefineSequence(CreateSeqStmt *seq)
NameData name;
/* Check and set all option values */
init_params(seq->options, true, &new, NULL, &owned_by);
init_params(seq->options, true, &new, &owned_by);
/*
* Create relation (and fill value[] and null[] for the tuple)
@ -357,8 +357,11 @@ AlterSequenceInternal(Oid relid, List *options)
seq = read_info(elm, seqrel, &buf);
page = BufferGetPage(buf);
/* Fill workspace with appropriate new info */
init_params(options, false, &new, seq, &owned_by);
/* Copy old values of options into workspace */
memcpy(&new, seq, sizeof(FormData_pg_sequence));
/* Check and set new values */
init_params(options, false, &new, &owned_by);
/* Clear local cache so that we don't think we have cached numbers */
/* Note that we do not change the currval() state */
@ -989,9 +992,10 @@ read_info(SeqTable elm, Relation rel, Buffer *buf)
*/
static void
init_params(List *options, bool isInit,
Form_pg_sequence new, Form_pg_sequence old, List **owned_by)
Form_pg_sequence new, List **owned_by)
{
DefElem *last_value = NULL;
DefElem *start_value = NULL;
DefElem *restart_value = NULL;
DefElem *increment_by = NULL;
DefElem *max_value = NULL;
DefElem *min_value = NULL;
@ -1001,12 +1005,6 @@ init_params(List *options, bool isInit,
*owned_by = NIL;
/* Copy old values of options into workspace */
if (old != NULL)
memcpy(new, old, sizeof(FormData_pg_sequence));
else
memset(new, 0, sizeof(FormData_pg_sequence));
foreach(option, options)
{
DefElem *defel = (DefElem *) lfirst(option);
@ -1021,27 +1019,19 @@ init_params(List *options, bool isInit,
}
else if (strcmp(defel->defname, "start") == 0)
{
if (!isInit)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("use RESTART not START in ALTER SEQUENCE")));
if (last_value)
if (start_value)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("conflicting or redundant options")));
last_value = defel;
start_value = defel;
}
else if (strcmp(defel->defname, "restart") == 0)
{
if (isInit)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("use START not RESTART in CREATE SEQUENCE")));
if (last_value)
if (restart_value)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR),
errmsg("conflicting or redundant options")));
last_value = defel;
restart_value = defel;
}
else if (strcmp(defel->defname, "maxvalue") == 0)
{
@ -1145,30 +1135,15 @@ init_params(List *options, bool isInit,
bufm, bufx)));
}
/* START/RESTART [WITH] */
if (last_value != NULL)
{
if (last_value->arg != NULL)
new->last_value = defGetInt64(last_value);
else
{
Assert(old != NULL);
new->last_value = old->start_value;
}
if (isInit)
new->start_value = new->last_value;
new->is_called = false;
new->log_cnt = 1;
}
/* START WITH */
if (start_value != NULL)
new->start_value = defGetInt64(start_value);
else if (isInit)
{
if (new->increment_by > 0)
new->start_value = new->min_value; /* ascending seq */
else
new->start_value = new->max_value; /* descending seq */
new->last_value = new->start_value;
new->is_called = false;
new->log_cnt = 1;
}
/* crosscheck START */
@ -1197,7 +1172,24 @@ init_params(List *options, bool isInit,
bufs, bufm)));
}
/* must crosscheck RESTART separately */
/* RESTART [WITH] */
if (restart_value != NULL)
{
if (restart_value->arg != NULL)
new->last_value = defGetInt64(restart_value);
else
new->last_value = new->start_value;
new->is_called = false;
new->log_cnt = 1;
}
else if (isInit)
{
new->last_value = new->start_value;
new->is_called = false;
new->log_cnt = 1;
}
/* crosscheck RESTART (or current value, if changing MIN/MAX) */
if (new->last_value < new->min_value)
{
char bufs[100],

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