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Create a "sort support" interface API for faster sorting.

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This patch creates an API whereby a btree index opclass can optionally
provide non-SQL-callable support functions for sorting.  In the initial
patch, we only use this to provide a directly-callable comparator function,
which can be invoked with a bit less overhead than the traditional
SQL-callable comparator.  While that should be of value in itself, the real
reason for doing this is to provide a datatype-extensible framework for
more aggressive optimizations, as in Peter Geoghegan's recent work.

Robert Haas and Tom Lane
This commit is contained in:
Tom Lane
2011-12-07 00:18:38 -05:00
parent d2a662182e
commit c6e3ac11b6
30 changed files with 869 additions and 421 deletions
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43
src/backend/utils/cache/lsyscache.c vendored
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@ -244,19 +244,22 @@ get_ordering_op_properties(Oid opno,
}
/*
* get_compare_function_for_ordering_op
* Get the OID of the datatype-specific btree comparison function
* get_sort_function_for_ordering_op
* Get the OID of the datatype-specific btree sort support function,
* or if there is none, the btree comparison function,
* associated with an ordering operator (a "<" or ">" operator).
*
* *cmpfunc receives the comparison function OID.
* *sortfunc receives the support or comparison function OID.
* *issupport is set TRUE if it's a support func, FALSE if a comparison func.
* *reverse is set FALSE if the operator is "<", TRUE if it's ">"
* (indicating the comparison result must be negated before use).
* (indicating that comparison results must be negated before use).
*
* Returns TRUE if successful, FALSE if no btree function can be found.
* (This indicates that the operator is not a valid ordering operator.)
*/
bool
get_compare_function_for_ordering_op(Oid opno, Oid *cmpfunc, bool *reverse)
get_sort_function_for_ordering_op(Oid opno, Oid *sortfunc,
bool *issupport, bool *reverse)
{
Oid opfamily;
Oid opcintype;
@ -267,21 +270,31 @@ get_compare_function_for_ordering_op(Oid opno, Oid *cmpfunc, bool *reverse)
&opfamily, &opcintype, &strategy))
{
/* Found a suitable opfamily, get matching support function */
*cmpfunc = get_opfamily_proc(opfamily,
opcintype,
opcintype,
BTORDER_PROC);
if (!OidIsValid(*cmpfunc)) /* should not happen */
elog(ERROR, "missing support function %d(%u,%u) in opfamily %u",
BTORDER_PROC, opcintype, opcintype, opfamily);
*sortfunc = get_opfamily_proc(opfamily,
opcintype,
opcintype,
BTSORTSUPPORT_PROC);
if (OidIsValid(*sortfunc))
*issupport = true;
else
{
/* opfamily doesn't provide sort support, get comparison func */
*sortfunc = get_opfamily_proc(opfamily,
opcintype,
opcintype,
BTORDER_PROC);
if (!OidIsValid(*sortfunc)) /* should not happen */
elog(ERROR, "missing support function %d(%u,%u) in opfamily %u",
BTORDER_PROC, opcintype, opcintype, opfamily);
*issupport = false;
}
*reverse = (strategy == BTGreaterStrategyNumber);
return true;
}
/* ensure outputs are set on failure */
*cmpfunc = InvalidOid;
*sortfunc = InvalidOid;
*issupport = false;
*reverse = false;
return false;
}