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Remove support for OR'd indexscans internal to a single IndexScan plan

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node, as this behavior is now better done as a bitmap OR indexscan.
This allows considerable simplification in nodeIndexscan.c itself as
well as several planner modules concerned with indexscan plan generation.
Also we can improve the sharing of code between regular and bitmap
indexscans, since they are now working with nigh-identical Plan nodes.
This commit is contained in:
Tom Lane
2005-04-25 01:30:14 +00:00
parent 186655e9a5
commit 5b05185262
21 changed files with 711 additions and 1924 deletions
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156
src/backend/optimizer/path/indxpath.c
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@ -9,7 +9,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/path/indxpath.c,v 1.177 2005/04/23 01:57:34 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/path/indxpath.c,v 1.178 2005/04/25 01:30:13 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -58,10 +58,6 @@ static List *find_usable_indexes(Query *root, RelOptInfo *rel,
List *clauses, List *outer_clauses,
bool istoplevel, bool isjoininner,
Relids outer_relids);
static List *generate_bitmap_or_paths(Query *root, RelOptInfo *rel,
List *clauses, List *outer_clauses,
bool isjoininner,
Relids outer_relids);
static Path *choose_bitmap_and(Query *root, RelOptInfo *rel, List *paths);
static int bitmap_path_comparator(const void *a, const void *b);
static Cost bitmap_and_cost_est(Query *root, RelOptInfo *rel, List *paths);
@ -365,7 +361,7 @@ find_usable_indexes(Query *root, RelOptInfo *rel,
* for the purpose of generating indexquals, but are not to be searched for
* ORs. (See find_usable_indexes() for motivation.)
*/
static List *
List *
generate_bitmap_or_paths(Query *root, RelOptInfo *rel,
List *clauses, List *outer_clauses,
bool isjoininner,
@ -520,11 +516,7 @@ choose_bitmap_and(Query *root, RelOptInfo *rel, List *paths)
paths = list_make1(patharray[0]);
costsofar = bitmap_and_cost_est(root, rel, paths);
if (IsA(patharray[0], IndexPath))
{
Assert(list_length(((IndexPath *) patharray[0])->indexclauses) == 1);
qualsofar = (List *) linitial(((IndexPath *) patharray[0])->indexclauses);
qualsofar = list_copy(qualsofar);
}
qualsofar = list_copy(((IndexPath *) patharray[0])->indexclauses);
else
qualsofar = NIL;
lastcell = list_head(paths); /* for quick deletions */
@ -537,8 +529,7 @@ choose_bitmap_and(Query *root, RelOptInfo *rel, List *paths)
if (IsA(newpath, IndexPath))
{
Assert(list_length(((IndexPath *) newpath)->indexclauses) == 1);
newqual = (List *) linitial(((IndexPath *) newpath)->indexclauses);
newqual = ((IndexPath *) newpath)->indexclauses;
if (list_difference(newqual, qualsofar) == NIL)
continue; /* redundant */
}
@ -714,108 +705,6 @@ group_clauses_by_indexkey(IndexOptInfo *index,
}
/*
* group_clauses_by_indexkey_for_or
* Generate a list of sublists of clauses that can be used with an index
* to find rows matching an OR subclause.
*
* This is essentially just like group_clauses_by_indexkey() except that
* we can use the given clause (or any AND subclauses of it) as well as
* top-level restriction clauses of the relation. Furthermore, we demand
* that at least one such use be made, otherwise we fail and return NIL.
* (Any path we made without such a use would be redundant with non-OR
* indexscans.)
*
* XXX When we generate an indexqual list that uses both the OR subclause
* and top-level restriction clauses, we end up with a slightly inefficient
* plan because create_indexscan_plan is not very bright about figuring out
* which restriction clauses are implied by the generated indexqual condition.
* Currently we'll end up rechecking both the OR clause and the top-level
* restriction clause as qpquals. FIXME someday.
*/
List *
group_clauses_by_indexkey_for_or(IndexOptInfo *index, Expr *orsubclause)
{
List *clausegroup_list = NIL;
bool matched = false;
int indexcol = 0;
Oid *classes = index->classlist;
do
{
Oid curClass = classes[0];
List *clausegroup = NIL;
ListCell *item;
/* Try to match the OR subclause to the index key */
if (IsA(orsubclause, RestrictInfo))
{
if (match_clause_to_indexcol(index, indexcol, curClass,
(RestrictInfo *) orsubclause,
NULL))
{
clausegroup = lappend(clausegroup, orsubclause);
matched = true;
}
}
else if (and_clause((Node *) orsubclause))
{
foreach(item, ((BoolExpr *) orsubclause)->args)
{
RestrictInfo *subsubclause = (RestrictInfo *) lfirst(item);
if (IsA(subsubclause, RestrictInfo) &&
match_clause_to_indexcol(index, indexcol, curClass,
subsubclause,
NULL))
{
clausegroup = lappend(clausegroup, subsubclause);
matched = true;
}
}
}
/*
* If we found no clauses for this indexkey in the OR subclause
* itself, try looking in the rel's top-level restriction list.
*
* XXX should we always search the top-level list? Slower but could
* sometimes yield a better plan.
*/
if (clausegroup == NIL)
{
foreach(item, index->rel->baserestrictinfo)
{
RestrictInfo *rinfo = (RestrictInfo *) lfirst(item);
if (match_clause_to_indexcol(index, indexcol, curClass,
rinfo,
NULL))
clausegroup = lappend(clausegroup, rinfo);
}
}
/*
* If still no clauses match this key, we're done; we don't want
* to look at keys to its right.
*/
if (clausegroup == NIL)
break;
clausegroup_list = lappend(clausegroup_list, clausegroup);
indexcol++;
classes++;
} while (!DoneMatchingIndexKeys(classes));
/* if OR clause was not used then forget it, per comments above */
if (!matched)
return NIL;
return clausegroup_list;
}
/*
* match_clause_to_indexcol()
* Determines whether a restriction clause matches a column of an index.
@ -2017,7 +1906,7 @@ find_clauses_for_join(Query *root, RelOptInfo *rel,
* of RestrictInfos.
*
* This is used to flatten out the result of group_clauses_by_indexkey()
* or one of its sibling routines, to produce an indexclauses list.
* to produce an indexclauses list.
*/
List *
flatten_clausegroups_list(List *clausegroups)
@ -2030,39 +1919,6 @@ flatten_clausegroups_list(List *clausegroups)
return allclauses;
}
/*
* make_expr_from_indexclauses()
* Given an indexclauses structure, produce an ordinary boolean expression.
*
* This consists of stripping out the RestrictInfo nodes and inserting
* explicit AND and OR nodes as needed. There's not much to it, but
* the functionality is needed in a few places, so centralize the logic.
*/
Expr *
make_expr_from_indexclauses(List *indexclauses)
{
List *orclauses = NIL;
ListCell *orlist;
/* There's no such thing as an indexpath with zero scans */
Assert(indexclauses != NIL);
foreach(orlist, indexclauses)
{
List *andlist = (List *) lfirst(orlist);
/* Strip RestrictInfos */
andlist = get_actual_clauses(andlist);
/* Insert AND node if needed, and add to orclauses list */
orclauses = lappend(orclauses, make_ands_explicit(andlist));
}
if (list_length(orclauses) > 1)
return make_orclause(orclauses);
else
return (Expr *) linitial(orclauses);
}
/****************************************************************************
* ---- ROUTINES TO CHECK OPERANDS ----
@ -2403,7 +2259,7 @@ match_special_index_operator(Expr *clause, Oid opclass,
*
* The input list is ordered by index key, and so the output list is too.
* (The latter is not depended on by any part of the planner, so far as I can
* tell; but some parts of the executor do assume that the indxqual list
* tell; but some parts of the executor do assume that the indexqual list
* ultimately delivered to the executor is so ordered. One such place is
* _bt_preprocess_keys() in the btree support. Perhaps that ought to be fixed
* someday --- tgl 7/00)