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CREATE INDEX ... INCLUDING (column[, ...])

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Now indexes (but only B-tree for now) can contain "extra" column(s) which
doesn't participate in index structure, they are just stored in leaf
tuples. It allows to use index only scan by using single index instead
of two or more indexes.

Author: Anastasia Lubennikova with minor editorializing by me
Reviewers: David Rowley, Peter Geoghegan, Jeff Janes
This commit is contained in:
Teodor Sigaev
2016-04-08 19:31:49 +03:00
parent 339025c68f
commit 386e3d7609
68 changed files with 1321 additions and 256 deletions
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36
doc/src/sgml/ref/create_table.sgml
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@@ -59,8 +59,8 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
[ CONSTRAINT <replaceable class="PARAMETER">constraint_name</replaceable> ]
{ CHECK ( <replaceable class="PARAMETER">expression</replaceable> ) [ NO INHERIT ] |
UNIQUE ( <replaceable class="PARAMETER">column_name</replaceable> [, ... ] ) <replaceable class="PARAMETER">index_parameters</replaceable> |
PRIMARY KEY ( <replaceable class="PARAMETER">column_name</replaceable> [, ... ] ) <replaceable class="PARAMETER">index_parameters</replaceable> |
UNIQUE ( <replaceable class="PARAMETER">column_name</replaceable> [, ... ] ) <replaceable class="PARAMETER">index_parameters</replaceable> <optional>INCLUDING (<replaceable class="PARAMETER">column_name</replaceable> [, ...])</optional> |
PRIMARY KEY ( <replaceable class="PARAMETER">column_name</replaceable> [, ... ] ) <replaceable class="PARAMETER">index_parameters</replaceable> <optional>INCLUDING (<replaceable class="PARAMETER">column_name</replaceable> [, ...])</optional> |
EXCLUDE [ USING <replaceable class="parameter">index_method</replaceable> ] ( <replaceable class="parameter">exclude_element</replaceable> WITH <replaceable class="parameter">operator</replaceable> [, ... ] ) <replaceable class="parameter">index_parameters</replaceable> [ WHERE ( <replaceable class="parameter">predicate</replaceable> ) ] |
FOREIGN KEY ( <replaceable class="PARAMETER">column_name</replaceable> [, ... ] ) REFERENCES <replaceable class="PARAMETER">reftable</replaceable> [ ( <replaceable class="PARAMETER">refcolumn</replaceable> [, ... ] ) ]
[ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ] [ ON DELETE <replaceable class="parameter">action</replaceable> ] [ ON UPDATE <replaceable class="parameter">action</replaceable> ] }
@@ -476,8 +476,8 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
<varlistentry>
<term><literal>UNIQUE</> (column constraint)</term>
<term><literal>UNIQUE ( <replaceable class="PARAMETER">column_name</replaceable> [, ... ] )</> (table constraint)</term>
<term><literal>UNIQUE ( <replaceable class="PARAMETER">column_name</replaceable> [, ... ] )
<optional>INCLUDING ( <replaceable class="PARAMETER">column_name</replaceable> [, ...])</optional></> (table constraint)</term>
<listitem>
<para>
The <literal>UNIQUE</literal> constraint specifies that a
@@ -498,12 +498,26 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
primary key constraint defined for the table. (Otherwise it
would just be the same constraint listed twice.)
</para>
<para>
Adding a unique constraint will automatically create a unique btree
index on the column or group of columns used in the constraint.
Optional clause <literal>INCLUDING</literal> allows to add into the index
a portion of columns on which the uniqueness is not enforced upon.
Note, that althogh constraint is not enforced upon included columns, it still
depends on them. Consequently, some operations on these columns (e.g. <literal>DROP COLUMN</literal>)
can cause cascade constraint and index deletion.
See paragraph about <literal>INCLUDING</literal> in
<xref linkend="SQL-CREATEINDEX"> for more information.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>PRIMARY KEY</> (column constraint)</term>
<term><literal>PRIMARY KEY ( <replaceable class="PARAMETER">column_name</replaceable> [, ... ] )</> (table constraint)</term>
<term><literal>PRIMARY KEY ( <replaceable class="PARAMETER">column_name</replaceable> [, ... ] )
<optional>INCLUDING ( <replaceable class="PARAMETER">column_name</replaceable> [, ...])</optional></> (table constraint)</term>
<listitem>
<para>
The <literal>PRIMARY KEY</> constraint specifies that a column or
@@ -526,6 +540,18 @@ CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXI
about the design of the schema, since a primary key implies that other
tables can rely on this set of columns as a unique identifier for rows.
</para>
<para>
Adding a <literal>PRIMARY KEY</literal> constraint will automatically create a unique btree
index on the column or group of columns used in the constraint.
Optional clause <literal>INCLUDING</literal> allows to add into the index
a portion of columns on which the constraint is not enforced upon.
Note, that althogh constraint is not enforced upon included columns, it still
depends on them. Consequently, some operations on these columns (e.g. <literal>DROP COLUMN</literal>)
can cause cascade constraint and index deletion.
See paragraph about <literal>INCLUDING</literal> in
<xref linkend="SQL-CREATEINDEX"> for more information.
</para>
</listitem>
</varlistentry>