database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-08-22 21:53:06 +03:00
Code Activity

Implement table partitioning.

Browse Source 
Table partitioning is like table inheritance and reuses much of the
existing infrastructure, but there are some important differences.
The parent is called a partitioned table and is always empty; it may
not have indexes or non-inherited constraints, since those make no
sense for a relation with no data of its own.  The children are called
partitions and contain all of the actual data.  Each partition has an
implicit partitioning constraint.  Multiple inheritance is not
allowed, and partitioning and inheritance can't be mixed.  Partitions
can't have extra columns and may not allow nulls unless the parent
does.  Tuples inserted into the parent are automatically routed to the
correct partition, so tuple-routing ON INSERT triggers are not needed.
Tuple routing isn't yet supported for partitions which are foreign
tables, and it doesn't handle updates that cross partition boundaries.

Currently, tables can be range-partitioned or list-partitioned.  List
partitioning is limited to a single column, but range partitioning can
involve multiple columns.  A partitioning "column" can be an
expression.

Because table partitioning is less general than table inheritance, it
is hoped that it will be easier to reason about properties of
partitions, and therefore that this will serve as a better foundation
for a variety of possible optimizations, including query planner
optimizations.  The tuple routing based which this patch does based on
the implicit partitioning constraints is an example of this, but it
seems likely that many other useful optimizations are also possible.

Amit Langote, reviewed and tested by Robert Haas, Ashutosh Bapat,
Amit Kapila, Rajkumar Raghuwanshi, Corey Huinker, Jaime Casanova,
Rushabh Lathia, Erik Rijkers, among others.  Minor revisions by me.
This commit is contained in:
Robert Haas
2016-12-07 13:17:43 -05:00
parent b7e1ae2328
commit f0e44751d7
85 changed files with 8896 additions and 281 deletions
Download Patch File Download Diff File Expand all files Collapse all files

154
doc/src/sgml/ref/create_table.sgml
View File

@@ -28,6 +28,7 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
[, ... ]
] )
[ INHERITS ( <replaceable>parent_table</replaceable> [, ... ] ) ]
[ PARTITION BY { RANGE | LIST } ( { <replaceable class="parameter">column_name</replaceable> | ( <replaceable class="parameter">expression</replaceable> ) } [ COLLATE <replaceable class="parameter">collation</replaceable> ] [ <replaceable class="parameter">opclass</replaceable> ] [, ... ] ) ]
[ WITH ( <replaceable class="PARAMETER">storage_parameter</replaceable> [= <replaceable class="PARAMETER">value</replaceable>] [, ... ] ) | WITH OIDS | WITHOUT OIDS ]
[ ON COMMIT { PRESERVE ROWS | DELETE ROWS | DROP } ]
[ TABLESPACE <replaceable class="PARAMETER">tablespace_name</replaceable> ]
@@ -38,6 +39,18 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
| <replaceable>table_constraint</replaceable> }
[, ... ]
) ]
[ PARTITION BY { RANGE | LIST } ( { <replaceable class="parameter">column_name</replaceable> | ( <replaceable class="parameter">expression</replaceable> ) } [ COLLATE <replaceable class="parameter">collation</replaceable> ] [ <replaceable class="parameter">opclass</replaceable> ] [, ... ] ) ]
[ WITH ( <replaceable class="PARAMETER">storage_parameter</replaceable> [= <replaceable class="PARAMETER">value</replaceable>] [, ... ] ) | WITH OIDS | WITHOUT OIDS ]
[ ON COMMIT { PRESERVE ROWS | DELETE ROWS | DROP } ]
[ TABLESPACE <replaceable class="PARAMETER">tablespace_name</replaceable> ]
CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXISTS ] <replaceable class="PARAMETER">table_name</replaceable>
PARTITION OF <replaceable class="PARAMETER">parent_table</replaceable> [ (
{ <replaceable class="PARAMETER">column_name</replaceable> [ <replaceable class="PARAMETER">column_constraint</replaceable> [ ... ] ]
| <replaceable>table_constraint</replaceable> }
[, ... ]
) ] FOR VALUES <replaceable class="PARAMETER">partition_bound_spec</replaceable>
[ PARTITION BY { RANGE | LIST } ( { <replaceable class="parameter">column_name</replaceable> | ( <replaceable class="parameter">expression</replaceable> ) } [ COLLATE <replaceable class="parameter">collation</replaceable> ] [ <replaceable class="parameter">opclass</replaceable> ] [, ... ] ) ]
[ WITH ( <replaceable class="PARAMETER">storage_parameter</replaceable> [= <replaceable class="PARAMETER">value</replaceable>] [, ... ] ) | WITH OIDS | WITHOUT OIDS ]
[ ON COMMIT { PRESERVE ROWS | DELETE ROWS | DROP } ]
[ TABLESPACE <replaceable class="PARAMETER">tablespace_name</replaceable> ]
@@ -70,6 +83,11 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
{ INCLUDING | EXCLUDING } { DEFAULTS | CONSTRAINTS | INDEXES | STORAGE | COMMENTS | ALL }
<phrase>and <replaceable class="PARAMETER">partition_bound_spec</replaceable> is:</phrase>
{ IN ( <replaceable class="PARAMETER">expression</replaceable> [, ...] ) |
FROM ( { <replaceable class="PARAMETER">expression</replaceable> | UNBOUNDED } [, ...] ) TO ( { <replaceable class="PARAMETER">expression</replaceable> | UNBOUNDED } [, ...] ) }
<phrase><replaceable class="PARAMETER">index_parameters</replaceable> in <literal>UNIQUE</literal>, <literal>PRIMARY KEY</literal>, and <literal>EXCLUDE</literal> constraints are:</phrase>
[ WITH ( <replaceable class="PARAMETER">storage_parameter</replaceable> [= <replaceable class="PARAMETER">value</replaceable>] [, ... ] ) ]
@@ -229,6 +247,51 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
</listitem>
</varlistentry>
<varlistentry>
<term><literal>PARTITION OF <replaceable class="PARAMETER">parent_table</replaceable></literal></term>
<listitem>
<para>
Creates the table as <firstterm>partition</firstterm> of the specified
parent table.
</para>
<para>
The partition bound specification must correspond to the partitioning
method and partition key of the parent table, and must not overlap with
any existing partition of that parent.
</para>
<para>
A partition cannot have columns other than those inherited from the
parent. That includes the <structfield>oid</> column, which can be
specified using the <literal>WITH (OIDS)</literal> clause.
Defaults and constraints can optionally be specified for each of the
inherited columns. One can also specify table constraints in addition
to those inherited from the parent. If a check constraint with the name
matching one of the parent's constraint is specified, it is merged with
the latter, provided the specified condition is same.
</para>
<para>
Rows inserted into a partitioned table will be automatically routed to
the correct partition. If no suitable partition exists, an error will
occur.
</para>
<para>
A partition must have the same column names and types as the table of
which it is a partition. Therefore, modifications to the column names
or types of the partitioned table will automatically propagate to all
children, as will operations such as TRUNCATE which normally affect a
table and all of its inheritance children. It is also possible to
TRUNCATE a partition individually, just as for an inheritance child.
Note that dropping a partition with <literal>DROP TABLE</literal>
requires taking an <literal>ACCESS EXCLUSIVE</literal> lock on the
parent table.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">column_name</replaceable></term>
<listitem>
@@ -313,6 +376,46 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
</listitem>
</varlistentry>
<varlistentry>
<term><literal>PARTITION BY { RANGE | LIST } ( { <replaceable class="parameter">column_name</replaceable> | ( <replaceable class="parameter">expression</replaceable> ) } [ <replaceable class="parameter">opclass</replaceable> ] [, ...] ) </literal></term>
<listitem>
<para>
The optional <literal>PARTITION BY</literal> clause specifies a strategy
of partitioning the table. The table thus created is called a
<firstterm>partitioned</firstterm> table. The parenthesized list of
columns or expressions forms the <firstterm>partition key</firstterm>
for the table. When using range partitioning, the partition key can
include multiple columns or expressions, but for list partitioning, the
partition key must consist of a single column or expression. If no
btree operator class is specified when creating a partitioned table,
the default btree operator class for the datatype will be used. If
there is none, an error will be reported.
</para>
<para>
A partitioned table is divided into sub-tables (called partitions),
which are created using separate <literal>CREATE TABLE</> commands.
The partitioned table is itself empty. A data row inserted into the
table is routed to a partition based on the value of columns or
expressions in the partition key. If no existing partition matches
the values in the new row, an error will be reported.
</para>
<para>
Partitioned tables do not support <literal>UNIQUE</literal>,
<literal>PRIMARY KEY</literal>, <literal>EXCLUDE</literal>, or
<literal>FOREIGN KEY</literal> constraints; however, you can define
these constraints on individual partitions.
</para>
<para>
When using range partitioning, a <literal>NOT NULL</literal> constraint
is added to each non-expression column in the partition key.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>LIKE <replaceable>source_table</replaceable> [ <replaceable>like_option</replaceable> ... ]</literal></term>
<listitem>
@@ -1368,6 +1471,57 @@ CREATE TABLE employees OF employee_type (
PRIMARY KEY (name),
salary WITH OPTIONS DEFAULT 1000
);
</programlisting></para>
<para>
Create a range partitioned table:
<programlisting>
CREATE TABLE measurement (
city_id int not null,
logdate date not null,
peaktemp int,
unitsales int
) PARTITION BY RANGE (logdate);
</programlisting></para>
<para>
Create a list partitioned table:
<programlisting>
CREATE TABLE cities (
name text not null,
population int,
) PARTITION BY LIST (initcap(name));
</programlisting></para>
<para>
Create partition of a range partitioned table:
<programlisting>
CREATE TABLE measurement_y2016m07
PARTITION OF measurement (
unitsales WITH OPTIONS DEFAULT 0
) FOR VALUES FROM ('2016-07-01') TO ('2016-08-01');
</programlisting></para>
<para>
Create partition of a list partitioned table:
<programlisting>
CREATE TABLE cities_west
PARTITION OF cities (
CONSTRAINT city_id_nonzero CHECK (city_id != 0)
) FOR VALUES IN ('Los Angeles', 'San Francisco');
</programlisting></para>
<para>
Create partition of a list partitioned table that is itself further
partitioned and then add a partition to it:
<programlisting>
CREATE TABLE cities_west
PARTITION OF cities (
CONSTRAINT city_id_nonzero CHECK (city_id != 0)
) FOR VALUES IN ('Los Angeles', 'San Francisco') PARTITION BY RANGE (population);
CREATE TABLE cities_west_10000_to_100000
PARTITION OF cities_west FOR VALUES FROM (10000) TO (100000);
</programlisting></para>
</refsect1>