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Push index operator lossiness determination down to GIST/GIN opclass

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"consistent" functions, and remove pg_amop.opreqcheck, as per recent
discussion.  The main immediate benefit of this is that we no longer need
8.3's ugly hack of requiring @@@ rather than @@ to test weight-using tsquery
searches on GIN indexes.  In future it should be possible to optimize some
other queries better than is done now, by detecting at runtime whether the
index match is exact or not.

Tom Lane, after an idea of Heikki's, and with some help from Teodor.
This commit is contained in:
Tom Lane
2008-04-14 17:05:34 +00:00
parent 10be77c173
commit 9b5c8d45f6
68 changed files with 1023 additions and 785 deletions
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30
doc/src/sgml/ref/create_opclass.sgml
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@@ -1,5 +1,5 @@
<!--
$PostgreSQL: pgsql/doc/src/sgml/ref/create_opclass.sgml,v 1.21 2007/12/03 23:49:51 tgl Exp $
$PostgreSQL: pgsql/doc/src/sgml/ref/create_opclass.sgml,v 1.22 2008/04/14 17:05:32 tgl Exp $
PostgreSQL documentation
-->
@@ -22,7 +22,7 @@ PostgreSQL documentation
<synopsis>
CREATE OPERATOR CLASS <replaceable class="parameter">name</replaceable> [ DEFAULT ] FOR TYPE <replaceable class="parameter">data_type</replaceable>
USING <replaceable class="parameter">index_method</replaceable> [ FAMILY <replaceable class="parameter">family_name</replaceable> ] AS
{ OPERATOR <replaceable class="parameter">strategy_number</replaceable> <replaceable class="parameter">operator_name</replaceable> [ ( <replaceable class="parameter">op_type</replaceable>, <replaceable class="parameter">op_type</replaceable> ) ] [ RECHECK ]
{ OPERATOR <replaceable class="parameter">strategy_number</replaceable> <replaceable class="parameter">operator_name</replaceable> [ ( <replaceable class="parameter">op_type</replaceable>, <replaceable class="parameter">op_type</replaceable> ) ]
| FUNCTION <replaceable class="parameter">support_number</replaceable> [ ( <replaceable class="parameter">op_type</replaceable> [ , <replaceable class="parameter">op_type</replaceable> ] ) ] <replaceable class="parameter">funcname</replaceable> ( <replaceable class="parameter">argument_type</replaceable> [, ...] )
| STORAGE <replaceable class="parameter">storage_type</replaceable>
} [, ... ]
@@ -179,18 +179,6 @@ CREATE OPERATOR CLASS <replaceable class="parameter">name</replaceable> [ DEFAUL
</listitem>
</varlistentry>
<varlistentry>
<term><literal>RECHECK</></term>
<listitem>
<para>
If present, the index is <quote>lossy</> for this operator, and
so the rows retrieved using the index must be rechecked to
verify that they actually satisfy the qualification clause
involving this operator.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">support_number</replaceable></term>
<listitem>
@@ -256,6 +244,14 @@ CREATE OPERATOR CLASS <replaceable class="parameter">name</replaceable> [ DEFAUL
is likely to be inlined into the calling query, which will prevent
the optimizer from recognizing that the query matches an index.
</para>
<para>
Before <productname>PostgreSQL</productname> 8.4, the <literal>OPERATOR</>
clause could include a <literal>RECHECK</> option. This is no longer
supported because whether an index operator is <quote>lossy</> is now
determined on-the-fly at runtime. This allows efficient handling of
cases where an operator might or might not be lossy.
</para>
</refsect1>
<refsect1>
@@ -271,12 +267,12 @@ CREATE OPERATOR CLASS <replaceable class="parameter">name</replaceable> [ DEFAUL
CREATE OPERATOR CLASS gist__int_ops
DEFAULT FOR TYPE _int4 USING gist AS
OPERATOR 3 &amp;&amp;,
OPERATOR 6 = RECHECK,
OPERATOR 6 = (anyarray, anyarray),
OPERATOR 7 @&gt;,
OPERATOR 8 &lt;@,
OPERATOR 20 @@ (_int4, query_int),
FUNCTION 1 g_int_consistent (internal, _int4, int4),
FUNCTION 2 g_int_union (bytea, internal),
FUNCTION 1 g_int_consistent (internal, _int4, int, oid, internal),
FUNCTION 2 g_int_union (internal, internal),
FUNCTION 3 g_int_compress (internal),
FUNCTION 4 g_int_decompress (internal),
FUNCTION 5 g_int_penalty (internal, internal, internal),