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Indexes with INCLUDE columns and their support in B-tree

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This patch introduces INCLUDE clause to index definition.  This clause
specifies a list of columns which will be included as a non-key part in
the index.  The INCLUDE columns exist solely to allow more queries to
benefit from index-only scans.  Also, such columns don't need to have
appropriate operator classes.  Expressions are not supported as INCLUDE
columns since they cannot be used in index-only scans.

Index access methods supporting INCLUDE are indicated by amcaninclude flag
in IndexAmRoutine.  For now, only B-tree indexes support INCLUDE clause.

In B-tree indexes INCLUDE columns are truncated from pivot index tuples
(tuples located in non-leaf pages and high keys).  Therefore, B-tree indexes
now might have variable number of attributes.  This patch also provides
generic facility to support that: pivot tuples contain number of their
attributes in t_tid.ip_posid.  Free 13th bit of t_info is used for indicating
that.  This facility will simplify further support of index suffix truncation.
The changes of above are backward-compatible, pg_upgrade doesn't need special
handling of B-tree indexes for that.

Bump catalog version

Author: Anastasia Lubennikova with contribition by Alexander Korotkov and me
Reviewed by: Peter Geoghegan, Tomas Vondra, Antonin Houska, Jeff Janes,
			 David Rowley, Alexander Korotkov
Discussion: https://www.postgresql.org/message-id/flat/56168952.4010101@postgrespro.ru
This commit is contained in:
Teodor Sigaev
2018-04-07 23:00:39 +03:00
parent 01bb85169a
commit 8224de4f42
89 changed files with 2112 additions and 467 deletions
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33
doc/src/sgml/ref/create_table.sgml
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@@ -73,8 +73,8 @@ 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> INCLUDE (<replaceable class="parameter">column_name</replaceable> [, ...]) </optional> |
PRIMARY KEY ( <replaceable class="parameter">column_name</replaceable> [, ... ] ) <replaceable class="parameter">index_parameters</replaceable> <optional> INCLUDE (<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> ] }
@@ -769,7 +769,8 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
<varlistentry>
<term><literal>UNIQUE</literal> (column constraint)</term>
<term><literal>UNIQUE ( <replaceable class="parameter">column_name</replaceable> [, ... ] )</literal> (table constraint)</term>
<term><literal>UNIQUE ( <replaceable class="parameter">column_name</replaceable> [, ... ] )</literal>
<optional> INCLUDE ( <replaceable class="parameter">column_name</replaceable> [, ...]) </optional> (table constraint)</term>
<listitem>
<para>
@@ -798,12 +799,25 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
partitioned table, as well as those of all its descendant partitioned
tables, must be included in the constraint definition.
</para>
<para>
Adding a unique constraint will automatically create a unique btree
index on the column or group of columns used in the constraint.
The optional clause <literal>INCLUDE</literal> adds to that index
one or more columns on which the uniqueness is not enforced.
Note that although the constraint is not enforced on the 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>INCLUDE</literal> in
<xref linkend="sql-createindex"/> for more information.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>PRIMARY KEY</literal> (column constraint)</term>
<term><literal>PRIMARY KEY ( <replaceable class="parameter">column_name</replaceable> [, ... ] )</literal> (table constraint)</term>
<term><literal>PRIMARY KEY ( <replaceable class="parameter">column_name</replaceable> [, ... ] )</literal>
<optional> INCLUDE ( <replaceable class="parameter">column_name</replaceable> [, ...]) </optional> (table constraint)</term>
<listitem>
<para>
The <literal>PRIMARY KEY</literal> constraint specifies that a column or
@@ -833,6 +847,17 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
tables.
</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. The optional <literal>INCLUDE</literal> clause allows a list
of columns to be specified which will be included in the non-key portion
of the index. Although uniqueness is not enforced on the included columns,
the constraint still depends on them. Consequently, some operations on the
included columns (e.g. <literal>DROP COLUMN</literal>) can cause cascade
constraint and index deletion. See paragraph about <literal>INCLUDE</literal>
in <xref linkend="sql-createindex"/> for more information.
</para>
</listitem>
</varlistentry>