seqname=DirectFunctionCall1(textin,

CStringGetDatum(args[i]));

newvals[chnattrs]=DirectFunctionCall1(nextval,seqname);

newvals[chnattrs]=Int32GetDatum((int32)DatumGetInt64(newvals[chnattrs]));

if (DatumGetInt32(newvals[chnattrs])==0)

{

newvals[chnattrs]=DirectFunctionCall1(nextval,seqname);

newvals[chnattrs]=Int32GetDatum((int32)DatumGetInt64(newvals[chnattrs]));

}

pfree(DatumGetTextP(seqname));

chnattrs++;

i++;

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$Header: /cvsroot/pgsql/doc/src/sgml/datatype.sgml,v 1.58 2001/08/16 20:38:53 tgl Exp $

-->

<chapter id="datatype">

<row>

<entry><type>serial</type></entry>

<entry></entry>

<entry><type>serial4</type></entry>

<entry>autoincrementing four-byte integer</entry>

</row>

<row>

<entry><type>serial8</type></entry>

<entry></entry>

<entry>autoincrementing eight-byte integer</entry>

</row>

<row>

<entry><type>text</type></entry>

<entry></entry>

</row>

<row>

<entry>serial</entry>

<entry>serial4</entry>

<entry>4 bytes</entry>

<entry>Identifier or cross-reference</entry>

<entry>0 to +2147483647</entry>

<entry>1 to 2147483647</entry>

</row>

<row>

<entry>serial8</entry>

<entry>8 bytes</entry>

<entry>Identifier or cross-reference</entry>

<entry>1 to 9223372036854775807</entry>

</row>

</tbody>

</tgroup>

</para>

<para>

The <type>bigint</type> type may not be available on all platforms since

it relies on compiler support for eight-byte integers.

The <type>bigint</type> type may not function correctly on all platforms,

since it relies on compiler support for eight-byte integers. On a machine

without such support, <type>bigint</type> acts the same

as <type>integer</type> (but still takes up eight bytes of storage).

</para>

<sect2 id="datatype-serial">

<title>The SerialType</title>

<title>The SerialTypes</title>

<indexterm zone="datatype-serial">

<primary>serial</primary>

</indexterm>

<indexterm zone="datatype-serial">

<primary>serial4</primary>

</indexterm>

<indexterm zone="datatype-serial">

<primary>serial8</primary>

</indexterm>

<indexterm>

<primary>auto-increment</primary>

<see>serial</see>

</indexterm>

<para>

The <type>serial</type>type is a special-case type constructed by

It is typically used to create unique identifiers for table entries.

The <type>serial</type>datatypes are not truly types, but are a

in tables.

In the current implementation, specifying

<programlisting>

<programlisting>

CREATE SEQUENCE <replaceable class="parameter">tablename</replaceable>_<replaceable class="parameter">colname</replaceable>_seq;

CREATE TABLE <replaceable class="parameter">tablename</replaceable>

(<replaceable class="parameter">colname</replaceable> integer DEFAULT nextval('<replaceable class="parameter">tablename</replaceable>_<replaceable class="parameter">colname</replaceable>_seq');

CREATE UNIQUE INDEX <replaceable class="parameter">tablename</replaceable>_<replaceable class="parameter">colname</replaceable>_key on <replaceable class="parameter">tablename</replaceable> (<replaceable class="parameter">colname</replaceable>);

(<replaceable class="parameter">colname</replaceable> integer DEFAULT nextval('<replaceable class="parameter">tablename</replaceable>_<replaceable class="parameter">colname</replaceable>_seq') UNIQUE NOT NULL;

</programlisting>

Thus, we have created an integer column and arranged for its default

values to be assigned from a sequence generator. UNIQUE and NOT NULL

constraints are applied to ensure that explicitly-inserted values

will never be duplicates, either.

<caution>

<para>

The implicit sequence created for the <type>serial</type> type will

<emphasis>not</emphasis> be automatically removed when the

table is dropped.

</para>

</caution>

</para>

<para>

The type names <type>serial</type> and <type>serial4</type> are

equivalent: both create <type>integer</type> columns. The type

name <type>serial8</type> works just the same way, except that it

creates a <type>bigint</type> column. <type>serial8</type> should

be used if you anticipate use of more than 2^31 identifiers over

the lifetime of the table.

</para>

<para>

Implicit sequences supporting the <type>serial</type> are

not automatically dropped when a table containing a serial type

is dropped. So, the following commands executed in order will likely fail:

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Postgres documentation

-->

The optional clause <option>MINVALUE

<replaceable class="parameter">minvalue</replaceable></option>

determines the minimum value

a sequence can generate. The defaults are 1 and -2147483647 for

a sequence can generate. The defaults are 1 and -2^63-1 for

ascending and descending sequences, respectively.

</para>

</listitem>

The optional clause <option>MAXVALUE

<replaceable class="parameter">maxvalue</replaceable></option>

determines the maximum

value for the sequence. The defaults are2147483647 and -1 for

value for the sequence. The defaults are2^63-1 and -1 for

ascending and descending sequences, respectively.

</para>

</listitem>

typename->typmod=attribute->atttypmod;

def->typename=typename;

def->is_not_null=attribute->attnotnull;

def->is_sequence= false;

def->raw_default=NULL;

def->cooked_default=NULL;

def->constraints=NIL;