</varlistentry>

</variablelist>

To implement these methods in a generic way, the operator class

defines its own internal support functions.

(For instance, the <quote>min/max</> operator classes implement

support functions for the four inequality operators for their data type.)

Additionally, the operator class must supply appropriate

operator entries,

to enable the optimizer to use the index when those operators are

used in queries.

The core distribution includes support for two types of operator classes:

minmax and inclusion. Operator class definitions using them are shipped for

in-core data types as appropriate. Additional operator classes can be

defined by the user for other datatypes using equivalent definitions,

without having to write any source code; appropriate catalog entries being

declared is enough. Note that assumptions about the semantics of operator

strategies are embedded in the support procedures's source code.

</para>

<para>

Operator classes that implement completely different semantics are also

possible, provided implementations of the four main support procedures

described above are written. Note that backwards compatibility across major

releases is not guaranteed: for example, additional support procedures might

be required in later releases.

</para>

<para>

To write an operator class for a datatype that implements a totally

ordered set, it is possible to use the Minmax support procedures

alongside the corresponding operators, as shown in

<xref linkend="brin-extensibility-minmax-table">.

All operator class members (procedures and operators) are mandatory.

</para>

<table id="brin-extensibility-minmax-table">

<title>Procedure and Support Numbers for Minmax Operator Classes</title>

<tgroup cols="2">

<thead>

<row>

<entry>Operator class member</entry>

<entry>Object</entry>

</row>

</thead>

<tbody>

<row>

<entry>Support Procedure 1</entry>

<entry>function <function>brin_minmax_opcinfo()</function></entry>

</row>

<row>

<entry>Support Procedure 2</entry>

<entry>function <function>brin_minmax_add_value()</function></entry>

</row>

<row>

<entry>Support Procedure 3</entry>

<entry>function <function>brin_minmax_consistent()</function></entry>

</row>

<row>

<entry>Support Procedure 4</entry>

<entry>function <function>brin_minmax_union()</function></entry>

</row>

<row>

<entry>Operator Strategy 1</entry>

<entry>operator less-than</entry>

</row>

<row>

<entry>Operator Strategy 2</entry>

<entry>operator less-than-or-equal-to</entry>

</row>

<row>

<entry>Operator Strategy 3</entry>

<entry>operator equal-to</entry>

</row>

<row>

<entry>Operator Strategy 4</entry>

<entry>operator greater-than-or-equal-to</entry>

</row>

<row>

<entry>Operator Strategy 5</entry>

<entry>operator greater-than</entry>

</row>

</tbody>

</tgroup>

</table>

</sect1>

</chapter>

brinbulkdelete(PG_FUNCTION_ARGS)

if (action==BLK_NEEDS_REDO)

{

Sizetuplen;

BrinTuple*mmtuple;

BrinTuple*brintuple;

Pagepage;

OffsetNumberoffnum;

mmtuple= (BrinTuple*)XLogRecGetBlockData(record,0,&tuplen);

brintuple= (BrinTuple*)XLogRecGetBlockData(record,0,&tuplen);

page= (Page)BufferGetPage(buffer);

elog(PANIC,"brin_xlog_samepage_update: invalid max offset number");

PageIndexDeleteNoCompact(page,&offnum,1);

offnum=PageAddItem(page, (Item)mmtuple,tuplen,offnum, true, false);

offnum=PageAddItem(page, (Item)brintuple,tuplen,offnum, true, false);

if (offnum==InvalidOffsetNumber)

elog(PANIC,"brin_xlog_samepage_update: failed to add tuple");