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Adjust the APIs for GIN opclass support functions to allow the extractQuery()

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method to pass extra data to the consistent() and comparePartial() methods.
This is the core infrastructure needed to support the soon-to-appear
contrib/btree_gin module.  The APIs are still upward compatible with the
definitions used in 8.3 and before, although *not* with the previous 8.4devel
function definitions.

catversion bump for changes in pg_proc entries (although these are just
cosmetic, since GIN doesn't actually look at the function signature before
calling it...)

Teodor Sigaev and Oleg Bartunov
This commit is contained in:
Tom Lane
2009-03-25 22:19:02 +00:00
parent 050a78dd3d
commit 87b8db3774
18 changed files with 210 additions and 148 deletions
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43
doc/src/sgml/gin.sgml
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@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/gin.sgml,v 2.17 2009/03/24 20:17:07 tgl Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/gin.sgml,v 2.18 2009/03/25 22:19:01 tgl Exp $ -->
<chapter id="GIN">
<title>GIN Indexes</title>
@ -88,7 +88,7 @@
<varlistentry>
<term>Datum *extractQuery(Datum query, int32 *nkeys,
StrategyNumber n, bool **pmatch)</term>
StrategyNumber n, bool **pmatch, Pointer **extra_data)</term>
<listitem>
<para>
Returns an array of keys given a value to be queried; that is,
@ -104,7 +104,7 @@
should store 0 or -1 into <literal>*nkeys</>, depending on the
semantics of the operator. 0 means that every
value matches the <literal>query</> and a sequential scan should be
produced. -1 means nothing can match the <literal>query</>.
performed. -1 means nothing can match the <literal>query</>.
<literal>pmatch</> is an output argument for use when partial match
is supported. To use it, <function>extractQuery</> must allocate
an array of <literal>*nkeys</> booleans and store its address at
@ -114,25 +114,40 @@
is not required. The variable is initialized to NULL before call,
so this argument can simply be ignored by operator classes that do
not support partial match.
<literal>extra_data</> is an output argument that allows
<function>extractQuery</> to pass additional data to the
<function>consistent</> and <function>comparePartial</> methods.
To use it, <function>extractQuery</> must allocate
an array of <literal>*nkeys</> Pointers and store its address at
<literal>*extra_data</>, then store whatever it wants to into the
individual pointers. The variable is initialized to NULL before
call, so this argument can simply be ignored by operator classes that
do not require extra data. If <literal>*extra_data</> is set, the
whole array is passed to the <function>consistent</> method, and
the appropriate element to the <function>comparePartial</> method.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>bool consistent(bool check[], StrategyNumber n, Datum query, bool *recheck)</term>
<term>bool consistent(bool check[], StrategyNumber n, Datum query,
int32 nkeys, Pointer extra_data[], bool *recheck)</term>
<listitem>
<para>
Returns TRUE if the indexed value satisfies the query operator with
strategy number <literal>n</> (or might satisfy, if the recheck
indication is returned). The <literal>check</> array has
the same length as the number of keys previously returned by
<function>extractQuery</> for this query. Each element of the
indication is returned). The <literal>check</> array has length
<literal>nkeys</>, which is the same as the number of keys previously
returned by <function>extractQuery</> for this <literal>query</> datum.
Each element of the
<literal>check</> array is TRUE if the indexed value contains the
corresponding query key, ie, if (check[i] == TRUE) the i-th key of the
<function>extractQuery</> result array is present in the indexed value.
The original <literal>query</> datum (not the extracted key array!) is
passed in case the <function>consistent</> method needs to consult it.
<literal>extra_data</> is the extra-data array returned by
<function>extractQuery</>, or NULL if none.
On success, <literal>*recheck</> should be set to TRUE if the heap
tuple needs to be rechecked against the query operator, or FALSE if
the index test is exact.
@ -150,7 +165,8 @@
<variablelist>
<varlistentry>
<term>int comparePartial(Datum partial_key, Datum key, StrategyNumber n)</term>
<term>int comparePartial(Datum partial_key, Datum key, StrategyNumber n,
Pointer extra_data)</term>
<listitem>
<para>
Compare a partial-match query to an index key. Returns an integer
@ -160,7 +176,9 @@
indicates that the index scan should stop because no more matches
are possible. The strategy number <literal>n</> of the operator
that generated the partial match query is provided, in case its
semantics are needed to determine when to end the scan.
semantics are needed to determine when to end the scan. Also,
<literal>extra_data</> is the corresponding element of the extra-data
array made by <function>extractQuery</>, or NULL if none.
</para>
</listitem>
</varlistentry>
@ -383,6 +401,13 @@
</para>
<variablelist>
<varlistentry>
<term>btree-gin</term>
<listitem>
<para>B-Tree equivalent functionality for several data types</para>
</listitem>
</varlistentry>
<varlistentry>
<term>hstore</term>
<listitem>