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Create core infrastructure for KNNGIST.

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This is a heavily revised version of builtin_knngist_core-0.9.  The
ordering operators are no longer mixed in with actual quals, which would
have confused not only humans but significant parts of the planner.
Instead, ordering operators are carried separately throughout planning and
execution.

Since the API for ambeginscan and amrescan functions had to be changed
anyway, this commit takes the opportunity to rationalize that a bit.
RelationGetIndexScan no longer forces a premature index_rescan call;
instead, callers of index_beginscan must call index_rescan too.  Aside from
making the AM-side initialization logic a bit less peculiar, this has the
advantage that we do not make a useless extra am_rescan call when there are
runtime key values.  AMs formerly could not assume that the key values
passed to amrescan were actually valid; now they can.

Teodor Sigaev and Tom Lane
This commit is contained in:
Tom Lane
2010-12-02 20:50:48 -05:00
parent d7e5d151da
commit d583f10b7e
40 changed files with 786 additions and 310 deletions
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198
src/backend/optimizer/path/indxpath.c
View File

@ -89,6 +89,9 @@ static bool match_rowcompare_to_indexcol(IndexOptInfo *index,
Oid opfamily,
RowCompareExpr *clause,
Relids outer_relids);
static List *match_index_to_pathkeys(IndexOptInfo *index, List *pathkeys);
static Expr *match_clause_to_ordering_op(IndexOptInfo *index,
int indexcol, Expr *clause, Oid pk_opfamily);
static Relids indexable_outerrelids(PlannerInfo *root, RelOptInfo *rel);
static bool matches_any_index(RestrictInfo *rinfo, RelOptInfo *rel,
Relids outer_relids);
@ -286,6 +289,7 @@ find_usable_indexes(PlannerInfo *root, RelOptInfo *rel,
IndexOptInfo *index = (IndexOptInfo *) lfirst(ilist);
IndexPath *ipath;
List *restrictclauses;
List *orderbyclauses;
List *index_pathkeys;
List *useful_pathkeys;
bool useful_predicate;
@ -388,9 +392,24 @@ find_usable_indexes(PlannerInfo *root, RelOptInfo *rel,
ForwardScanDirection);
useful_pathkeys = truncate_useless_pathkeys(root, rel,
index_pathkeys);
orderbyclauses = NIL;
}
else if (index->amcanorderbyop && possibly_useful_pathkeys &&
istoplevel && outer_rel == NULL && scantype != ST_BITMAPSCAN)
{
/* see if we can generate ordering operators for query_pathkeys */
orderbyclauses = match_index_to_pathkeys(index,
root->query_pathkeys);
if (orderbyclauses)
useful_pathkeys = root->query_pathkeys;
else
useful_pathkeys = NIL;
}
else
{
useful_pathkeys = NIL;
orderbyclauses = NIL;
}
/*
* 3. Generate an indexscan path if there are relevant restriction
@ -402,6 +421,7 @@ find_usable_indexes(PlannerInfo *root, RelOptInfo *rel,
{
ipath = create_index_path(root, index,
restrictclauses,
orderbyclauses,
useful_pathkeys,
index_is_ordered ?
ForwardScanDirection :
@ -425,6 +445,7 @@ find_usable_indexes(PlannerInfo *root, RelOptInfo *rel,
{
ipath = create_index_path(root, index,
restrictclauses,
NIL,
useful_pathkeys,
BackwardScanDirection,
outer_rel);
@ -1384,6 +1405,179 @@ match_rowcompare_to_indexcol(IndexOptInfo *index,
}
/****************************************************************************
* ---- ROUTINES TO CHECK ORDERING OPERATORS ----
****************************************************************************/
/*
* match_index_to_pathkeys
* Test whether an index can produce output ordered according to the
* given pathkeys using "ordering operators".
*
* If it can, return a list of suitable ORDER BY expressions, each of the form
* "indexedcol operator pseudoconstant". If not, return NIL.
*/
static List *
match_index_to_pathkeys(IndexOptInfo *index, List *pathkeys)
{
List *orderbyexprs = NIL;
ListCell *lc1;
/* Only indexes with the amcanorderbyop property are interesting here */
if (!index->amcanorderbyop)
return NIL;
foreach(lc1, pathkeys)
{
PathKey *pathkey = (PathKey *) lfirst(lc1);
bool found = false;
ListCell *lc2;
/*
* Note: for any failure to match, we just return NIL immediately.
* There is no value in matching just some of the pathkeys.
*/
/* Pathkey must request default sort order for the target opfamily */
if (pathkey->pk_strategy != BTLessStrategyNumber ||
pathkey->pk_nulls_first)
return NIL;
/* If eclass is volatile, no hope of using an indexscan */
if (pathkey->pk_eclass->ec_has_volatile)
return NIL;
/* Try to match eclass member expression(s) to index */
foreach(lc2, pathkey->pk_eclass->ec_members)
{
EquivalenceMember *member = (EquivalenceMember *) lfirst(lc2);
int indexcol;
/* No possibility of match if it references other relations */
if (!bms_equal(member->em_relids, index->rel->relids))
continue;
for (indexcol = 0; indexcol < index->ncolumns; indexcol++)
{
Expr *expr;
expr = match_clause_to_ordering_op(index,
indexcol,
member->em_expr,
pathkey->pk_opfamily);
if (expr)
{
orderbyexprs = lappend(orderbyexprs, expr);
found = true;
break;
}
}
if (found) /* don't want to look at remaining members */
break;
}
if (!found) /* fail if no match for this pathkey */
return NIL;
}
return orderbyexprs; /* success! */
}
/*
* match_clause_to_ordering_op
* Determines whether an ordering operator expression matches an
* index column.
*
* This is similar to, but simpler than, match_clause_to_indexcol.
* We only care about simple OpExpr cases. The input is a bare
* expression that is being ordered by, which must be of the form
* (indexkey op const) or (const op indexkey) where op is an ordering
* operator for the column's opfamily.
*
* 'index' is the index of interest.
* 'indexcol' is a column number of 'index' (counting from 0).
* 'clause' is the ordering expression to be tested.
* 'pk_opfamily' is the btree opfamily describing the required sort order.
*
* If successful, return 'clause' as-is if the indexkey is on the left,
* otherwise a commuted copy of 'clause'. If no match, return NULL.
*/
static Expr *
match_clause_to_ordering_op(IndexOptInfo *index,
int indexcol,
Expr *clause,
Oid pk_opfamily)
{
Oid opfamily = index->opfamily[indexcol];
Node *leftop,
*rightop;
Oid expr_op;
Oid sortfamily;
bool commuted;
/*
* Clause must be a binary opclause.
*/
if (!is_opclause(clause))
return NULL;
leftop = get_leftop(clause);
rightop = get_rightop(clause);
if (!leftop || !rightop)
return NULL;
expr_op = ((OpExpr *) clause)->opno;
/*
* Check for clauses of the form: (indexkey operator constant) or
* (constant operator indexkey).
*/
if (match_index_to_operand(leftop, indexcol, index) &&
!contain_var_clause(rightop) &&
!contain_volatile_functions(rightop))
{
commuted = false;
}
else if (match_index_to_operand(rightop, indexcol, index) &&
!contain_var_clause(leftop) &&
!contain_volatile_functions(leftop))
{
/* Might match, but we need a commuted operator */
expr_op = get_commutator(expr_op);
if (expr_op == InvalidOid)
return NULL;
commuted = true;
}
else
return NULL;
/*
* Is the (commuted) operator an ordering operator for the opfamily?
* And if so, does it yield the right sorting semantics?
*/
sortfamily = get_op_opfamily_sortfamily(expr_op, opfamily);
if (sortfamily != pk_opfamily)
return NULL;
/* We have a match. Return clause or a commuted version thereof. */
if (commuted)
{
OpExpr *newclause = makeNode(OpExpr);
/* flat-copy all the fields of clause */
memcpy(newclause, clause, sizeof(OpExpr));
/* commute it */
newclause->opno = expr_op;
newclause->opfuncid = InvalidOid;
newclause->args = list_make2(rightop, leftop);
clause = (Expr *) newclause;
}
return clause;
}
/****************************************************************************
* ---- ROUTINES TO DO PARTIAL INDEX PREDICATE TESTS ----
****************************************************************************/
@ -2630,7 +2824,7 @@ expand_indexqual_rowcompare(RestrictInfo *rinfo,
expr_op = linitial_oid(clause->opnos);
if (!var_on_left)
expr_op = get_commutator(expr_op);
get_op_opfamily_properties(expr_op, index->opfamily[indexcol],
get_op_opfamily_properties(expr_op, index->opfamily[indexcol], false,
&op_strategy,
&op_lefttype,
&op_righttype);
@ -2698,7 +2892,7 @@ expand_indexqual_rowcompare(RestrictInfo *rinfo,
break;
/* Add opfamily and datatypes to lists */
get_op_opfamily_properties(expr_op, index->opfamily[i],
get_op_opfamily_properties(expr_op, index->opfamily[i], false,
&op_strategy,
&op_lefttype,
&op_righttype);