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Improve partitioning example, per Itagaki Takahiro.

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This commit is contained in:
Tom Lane 2007-12-03 04:59:55 +00:00
parent 531f58688a
commit 57da4cca27
1 changed files with 16 additions and 6 deletions
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22
doc/src/sgml/ddl.sgml
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@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/ddl.sgml,v 1.78 2007/12/02 19:20:32 tgl Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/ddl.sgml,v 1.79 2007/12/03 04:59:55 tgl Exp $ -->
<chapter id="ddl">
<title>Data Definition</title>
@ -2466,8 +2466,9 @@ CREATE TABLE measurement_y2008m01 ( ) INHERITS (measurement);
<listitem>
<para>
We must add non-overlapping table constraints, so that our
table creation script becomes:
We must provide non-overlapping table constraints. Rather than
just creating the partition tables as above, the table creation
script should really be:
<programlisting>
CREATE TABLE measurement_y2006m02 (
@ -2550,12 +2551,12 @@ CREATE TRIGGER insert_measurement_trigger
CREATE OR REPLACE FUNCTION measurement_insert_trigger()
RETURNS TRIGGER AS $$
BEGIN
IF ( logdate &gt;= DATE '2006-02-01' AND logdate &lt; DATE '2006-03-01' ) THEN
IF ( NEW.logdate &gt;= DATE '2006-02-01' AND NEW.logdate &lt; DATE '2006-03-01' ) THEN
INSERT INTO measurement_y2006m02 VALUES (NEW.*);
ELSIF ( logdate &gt;= DATE '2006-03-01' AND logdate &lt; DATE '2006-04-01' ) THEN
ELSIF ( NEW.logdate &gt;= DATE '2006-03-01' AND NEW.logdate &lt; DATE '2006-04-01' ) THEN
INSERT INTO measurement_y2006m03 VALUES (NEW.*);
...
ELSIF ( logdate &gt;= DATE '2008-01-01' AND logdate &lt; DATE '2008-02-01' ) THEN
ELSIF ( NEW.logdate &gt;= DATE '2008-01-01' AND NEW.logdate &lt; DATE '2008-02-01' ) THEN
INSERT INTO measurement_y2008m01 VALUES (NEW.*);
ELSE
RAISE EXCEPTION 'Date out of range. Fix the measurement_insert_trigger() function!';
@ -2576,6 +2577,15 @@ LANGUAGE plpgsql;
it doesn't need to be updated as often, since branches can be
added in advance of being needed.
</para>
<note>
<para>
In practice it might be best to check the newest partition first,
if most inserts go into that partition. For simplicity we have
shown the trigger's tests in the same order as in other parts
of this example.
</para>
</note>
</listitem>
</orderedlist>
</para>