* the nature and use of path keys.
*
*
- * Portions Copyright (c) 1996-2000, PostgreSQL, Inc
+ * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/optimizer/path/pathkeys.c,v 1.28 2000/12/14 22:30:43 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/optimizer/path/pathkeys.c,v 1.72 2005/08/27 22:13:43 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "optimizer/paths.h"
#include "optimizer/planmain.h"
#include "optimizer/tlist.h"
+#include "optimizer/var.h"
#include "parser/parsetree.h"
+#include "parser/parse_expr.h"
#include "parser/parse_func.h"
#include "utils/lsyscache.h"
-
-
-static PathKeyItem *makePathKeyItem(Node *key, Oid sortop);
-static List *make_canonical_pathkey(Query *root, PathKeyItem *item);
-static Var *find_indexkey_var(Query *root, RelOptInfo *rel,
- AttrNumber varattno);
+#include "utils/memutils.h"
+
+
+static PathKeyItem *makePathKeyItem(Node *key, Oid sortop, bool checkType);
+static void generate_outer_join_implications(PlannerInfo *root,
+ List *equi_key_set,
+ Relids *relids);
+static void sub_generate_join_implications(PlannerInfo *root,
+ List *equi_key_set, Relids *relids,
+ Node *item1, Oid sortop1,
+ Relids item1_relids);
+static void process_implied_const_eq(PlannerInfo *root,
+ List *equi_key_set, Relids *relids,
+ Node *item1, Oid sortop1,
+ Relids item1_relids,
+ bool delete_it);
+static List *make_canonical_pathkey(PlannerInfo *root, PathKeyItem *item);
+static Var *find_indexkey_var(PlannerInfo *root, RelOptInfo *rel,
+ AttrNumber varattno);
/*
* create a PathKeyItem node
*/
static PathKeyItem *
-makePathKeyItem(Node *key, Oid sortop)
+makePathKeyItem(Node *key, Oid sortop, bool checkType)
{
PathKeyItem *item = makeNode(PathKeyItem);
+ /*
+ * Some callers pass expressions that are not necessarily of the same
+ * type as the sort operator expects as input (for example when
+ * dealing with an index that uses binary-compatible operators). We
+ * must relabel these with the correct type so that the key
+ * expressions will be seen as equal() to expressions that have been
+ * correctly labeled.
+ */
+ if (checkType)
+ {
+ Oid lefttype,
+ righttype;
+
+ op_input_types(sortop, &lefttype, &righttype);
+ if (exprType(key) != lefttype)
+ key = (Node *) makeRelabelType((Expr *) key,
+ lefttype, -1,
+ COERCE_DONTCARE);
+ }
+
item->key = key;
item->sortop = sortop;
return item;
* The given clause has a mergejoinable operator, so its two sides
* can be considered equal after restriction clause application; in
* particular, any pathkey mentioning one side (with the correct sortop)
- * can be expanded to include the other as well. Record the vars and
+ * can be expanded to include the other as well. Record the exprs and
* associated sortops in the query's equi_key_list for future use.
*
* The query's equi_key_list field points to a list of sublists of PathKeyItem
- * nodes, where each sublist is a set of two or more vars+sortops that have
+ * nodes, where each sublist is a set of two or more exprs+sortops that have
* been identified as logically equivalent (and, therefore, we may consider
* any two in a set to be equal). As described above, we will subsequently
* use direct pointers to one of these sublists to represent any pathkey
* that involves an equijoined variable.
- *
- * This code would actually work fine with expressions more complex than
- * a single Var, but currently it won't see any because check_mergejoinable
- * won't accept such clauses as mergejoinable.
*/
void
-add_equijoined_keys(Query *root, RestrictInfo *restrictinfo)
+add_equijoined_keys(PlannerInfo *root, RestrictInfo *restrictinfo)
{
Expr *clause = restrictinfo->clause;
- PathKeyItem *item1 = makePathKeyItem((Node *) get_leftop(clause),
- restrictinfo->left_sortop);
- PathKeyItem *item2 = makePathKeyItem((Node *) get_rightop(clause),
- restrictinfo->right_sortop);
- List *newset,
- *cursetlink;
+ PathKeyItem *item1 = makePathKeyItem(get_leftop(clause),
+ restrictinfo->left_sortop,
+ false);
+ PathKeyItem *item2 = makePathKeyItem(get_rightop(clause),
+ restrictinfo->right_sortop,
+ false);
+ List *newset;
+ ListCell *cursetlink;
/* We might see a clause X=X; don't make a single-element list from it */
if (equal(item1, item2))
* into our new set. When done, we add the new set to the front of
* equi_key_list.
*
- * It may well be that the two items we're given are already known to
- * be equijoin-equivalent, in which case we don't need to change our
- * data structure. If we find both of them in the same equivalence
- * set to start with, we can quit immediately.
+ * It may well be that the two items we're given are already known to be
+ * equijoin-equivalent, in which case we don't need to change our data
+ * structure. If we find both of them in the same equivalence set to
+ * start with, we can quit immediately.
*
* This is a standard UNION-FIND problem, for which there exist better
* data structures than simple lists. If this code ever proves to be
*/
newset = NIL;
- foreach(cursetlink, root->equi_key_list)
+ /* cannot use foreach here because of possible lremove */
+ cursetlink = list_head(root->equi_key_list);
+ while (cursetlink)
{
- List *curset = lfirst(cursetlink);
- bool item1here = member(item1, curset);
- bool item2here = member(item2, curset);
+ List *curset = (List *) lfirst(cursetlink);
+ bool item1here = list_member(curset, item1);
+ bool item2here = list_member(curset, item2);
+
+ /* must advance cursetlink before lremove possibly pfree's it */
+ cursetlink = lnext(cursetlink);
if (item1here || item2here)
{
- /* If find both in same equivalence set, no need to do any more */
+ /*
+ * If find both in same equivalence set, no need to do any
+ * more
+ */
if (item1here && item2here)
{
/* Better not have seen only one in an earlier set... */
/* Build the new set only when we know we must */
if (newset == NIL)
- newset = lcons(item1, lcons(item2, NIL));
+ newset = list_make2(item1, item2);
/* Found a set to merge into our new set */
- newset = set_union(newset, curset);
+ newset = list_concat_unique(newset, curset);
/*
- * Remove old set from equi_key_list. NOTE this does not
- * change lnext(cursetlink), so the foreach loop doesn't break.
+ * Remove old set from equi_key_list.
*/
- root->equi_key_list = lremove(curset, root->equi_key_list);
- freeList(curset); /* might as well recycle old cons cells */
+ root->equi_key_list = list_delete_ptr(root->equi_key_list, curset);
+ list_free(curset); /* might as well recycle old cons cells */
}
}
/* Build the new set only when we know we must */
if (newset == NIL)
- newset = lcons(item1, lcons(item2, NIL));
+ newset = list_make2(item1, item2);
root->equi_key_list = lcons(newset, root->equi_key_list);
}
* generate_implied_equalities
* Scan the completed equi_key_list for the query, and generate explicit
* qualifications (WHERE clauses) for all the pairwise equalities not
- * already mentioned in the quals. This is useful because the additional
- * clauses help the selectivity-estimation code, and in fact it's
- * *necessary* to ensure that sort keys we think are equivalent really
- * are (see src/backend/optimizer/README for more info).
+ * already mentioned in the quals; or remove qualifications found to be
+ * redundant.
+ *
+ * Adding deduced equalities is useful because the additional clauses help
+ * the selectivity-estimation code and may allow better joins to be chosen;
+ * and in fact it's *necessary* to ensure that sort keys we think are
+ * equivalent really are (see src/backend/optimizer/README for more info).
+ *
+ * If an equi_key_list set includes any constants then we adopt a different
+ * strategy: we record all the "var = const" deductions we can make, and
+ * actively remove all the "var = var" clauses that are implied by the set
+ * (including the clauses that originally gave rise to the set!). The reason
+ * is that given input like "a = b AND b = 42", once we have deduced "a = 42"
+ * there is no longer any need to apply the clause "a = b"; not only is
+ * it a waste of time to check it, but we will misestimate selectivity if the
+ * clause is left in. So we must remove it. For this purpose, any pathkey
+ * item that mentions no Vars of the current level can be taken as a constant.
+ * (The only case where this would be risky is if the item contains volatile
+ * functions; but we will never consider such an expression to be a pathkey
+ * at all, because check_mergejoinable() will reject it.)
+ *
+ * Also, when we have constants in an equi_key_list we can try to propagate
+ * the constants into outer joins; see generate_outer_join_implications
+ * for discussion.
*
* This routine just walks the equi_key_list to find all pairwise equalities.
- * We call process_implied_equality (in plan/initsplan.c) to determine whether
- * each is already known and add it to the proper restrictinfo list if not.
+ * We call process_implied_equality (in plan/initsplan.c) to adjust the
+ * restrictinfo datastructures for each pair.
*/
void
-generate_implied_equalities(Query *root)
+generate_implied_equalities(PlannerInfo *root)
{
- List *cursetlink;
+ ListCell *cursetlink;
foreach(cursetlink, root->equi_key_list)
{
- List *curset = lfirst(cursetlink);
- List *ptr1;
+ List *curset = (List *) lfirst(cursetlink);
+ int nitems = list_length(curset);
+ Relids *relids;
+ bool have_consts;
+ ListCell *ptr1;
+ int i1;
/*
* A set containing only two items cannot imply any equalities
- * beyond the one that created the set, so we can skip it.
+ * beyond the one that created the set, so we can skip it ---
+ * unless outer joins appear in the query.
*/
- if (length(curset) < 3)
+ if (nitems < 3 && !root->hasOuterJoins)
continue;
/*
- * Match each item in the set with all that appear after it
- * (it's sufficient to generate A=B, need not process B=A too).
+ * Collect info about relids mentioned in each item. For this
+ * routine we only really care whether there are any at all in
+ * each item, but process_implied_equality() needs the exact sets,
+ * so we may as well pull them here.
*/
+ relids = (Relids *) palloc(nitems * sizeof(Relids));
+ have_consts = false;
+ i1 = 0;
foreach(ptr1, curset)
{
PathKeyItem *item1 = (PathKeyItem *) lfirst(ptr1);
- List *ptr2;
- foreach(ptr2, lnext(ptr1))
+ relids[i1] = pull_varnos(item1->key);
+ if (bms_is_empty(relids[i1]))
+ have_consts = true;
+ i1++;
+ }
+
+ /*
+ * Match each item in the set with all that appear after it (it's
+ * sufficient to generate A=B, need not process B=A too).
+ *
+ * A set containing only two items cannot imply any equalities
+ * beyond the one that created the set, so we can skip this
+ * processing in that case.
+ */
+ if (nitems >= 3)
+ {
+ i1 = 0;
+ foreach(ptr1, curset)
+ {
+ PathKeyItem *item1 = (PathKeyItem *) lfirst(ptr1);
+ bool i1_is_variable = !bms_is_empty(relids[i1]);
+ ListCell *ptr2;
+ int i2 = i1 + 1;
+
+ for_each_cell(ptr2, lnext(ptr1))
+ {
+ PathKeyItem *item2 = (PathKeyItem *) lfirst(ptr2);
+ bool i2_is_variable = !bms_is_empty(relids[i2]);
+
+ /*
+ * If it's "const = const" then just ignore it altogether.
+ * There is no place in the restrictinfo structure to
+ * store it. (If the two consts are in fact unequal, then
+ * propagating the comparison to Vars will cause us to
+ * produce zero rows out, as expected.)
+ */
+ if (i1_is_variable || i2_is_variable)
+ {
+ /*
+ * Tell process_implied_equality to delete the clause,
+ * not add it, if it's "var = var" and we have
+ * constants present in the list.
+ */
+ bool delete_it = (have_consts &&
+ i1_is_variable &&
+ i2_is_variable);
+
+ process_implied_equality(root,
+ item1->key, item2->key,
+ item1->sortop, item2->sortop,
+ relids[i1], relids[i2],
+ delete_it);
+ }
+ i2++;
+ }
+ i1++;
+ }
+ }
+
+ /*
+ * If we have constant(s) and outer joins, try to propagate the
+ * constants through outer-join quals.
+ */
+ if (have_consts && root->hasOuterJoins)
+ generate_outer_join_implications(root, curset, relids);
+ }
+}
+
+/*
+ * generate_outer_join_implications
+ * Generate clauses that can be deduced in outer-join situations.
+ *
+ * When we have mergejoinable clauses A = B that are outer-join clauses,
+ * we can't blindly combine them with other clauses A = C to deduce B = C,
+ * since in fact the "equality" A = B won't necessarily hold above the
+ * outer join (one of the variables might be NULL instead). Nonetheless
+ * there are cases where we can add qual clauses using transitivity.
+ *
+ * One case that we look for here is an outer-join clause OUTERVAR = INNERVAR
+ * combined with a pushed-down (valid everywhere) clause OUTERVAR = CONSTANT.
+ * It is safe and useful to push a clause INNERVAR = CONSTANT into the
+ * evaluation of the inner (nullable) relation, because any inner rows not
+ * meeting this condition will not contribute to the outer-join result anyway.
+ * (Any outer rows they could join to will be eliminated by the pushed-down
+ * clause.)
+ *
+ * Note that the above rule does not work for full outer joins, nor for
+ * pushed-down restrictions on an inner-side variable; nor is it very
+ * interesting to consider cases where the pushed-down clause involves
+ * relations entirely outside the outer join, since such clauses couldn't
+ * be pushed into the inner side's scan anyway. So the restriction to
+ * outervar = pseudoconstant is not really giving up anything.
+ *
+ * For full-join cases, we can only do something useful if it's a FULL JOIN
+ * USING and a merged column has a restriction MERGEDVAR = CONSTANT. By
+ * the time it gets here, the restriction will look like
+ * COALESCE(LEFTVAR, RIGHTVAR) = CONSTANT
+ * and we will have a join clause LEFTVAR = RIGHTVAR that we can match the
+ * COALESCE expression to. In this situation we can push LEFTVAR = CONSTANT
+ * and RIGHTVAR = CONSTANT into the input relations, since any rows not
+ * meeting these conditions cannot contribute to the join result.
+ *
+ * Again, there isn't any traction to be gained by trying to deal with
+ * clauses comparing a mergedvar to a non-pseudoconstant. So we can make
+ * use of the equi_key_lists to quickly find the interesting pushed-down
+ * clauses. The interesting outer-join clauses were accumulated for us by
+ * distribute_qual_to_rels.
+ *
+ * equi_key_set: a list of PathKeyItems that are known globally equivalent,
+ * at least one of which is a pseudoconstant.
+ * relids: an array of Relids sets showing the relation membership of each
+ * PathKeyItem in equi_key_set.
+ */
+static void
+generate_outer_join_implications(PlannerInfo *root,
+ List *equi_key_set,
+ Relids *relids)
+{
+ ListCell *l;
+ int i = 0;
+
+ /* Process each non-constant element of equi_key_set */
+ foreach(l, equi_key_set)
+ {
+ PathKeyItem *item1 = (PathKeyItem *) lfirst(l);
+
+ if (!bms_is_empty(relids[i]))
+ {
+ sub_generate_join_implications(root, equi_key_set, relids,
+ item1->key,
+ item1->sortop,
+ relids[i]);
+ }
+ i++;
+ }
+}
+
+/*
+ * sub_generate_join_implications
+ * Propagate a constant equality through outer join clauses.
+ *
+ * The item described by item1/sortop1/item1_relids has been determined
+ * to be equal to the constant(s) listed in equi_key_set. Recursively
+ * trace out the implications of this.
+ *
+ * equi_key_set and relids are as for generate_outer_join_implications.
+ */
+static void
+sub_generate_join_implications(PlannerInfo *root,
+ List *equi_key_set, Relids *relids,
+ Node *item1, Oid sortop1, Relids item1_relids)
+
+{
+ ListCell *l;
+
+ /*
+ * Examine each mergejoinable outer-join clause with OUTERVAR on left,
+ * looking for an OUTERVAR identical to item1
+ */
+ foreach(l, root->left_join_clauses)
+ {
+ RestrictInfo *rinfo = (RestrictInfo *) lfirst(l);
+ Node *leftop = get_leftop(rinfo->clause);
+
+ if (equal(leftop, item1) && rinfo->left_sortop == sortop1)
+ {
+ /*
+ * Match, so find constant member(s) of set and generate
+ * implied INNERVAR = CONSTANT
+ */
+ Node *rightop = get_rightop(rinfo->clause);
+
+ process_implied_const_eq(root, equi_key_set, relids,
+ rightop,
+ rinfo->right_sortop,
+ rinfo->right_relids,
+ false);
+ /*
+ * We can remove explicit tests of this outer-join qual, too,
+ * since we now have tests forcing each of its sides
+ * to the same value.
+ */
+ process_implied_equality(root,
+ leftop, rightop,
+ rinfo->left_sortop, rinfo->right_sortop,
+ rinfo->left_relids, rinfo->right_relids,
+ true);
+ /*
+ * And recurse to see if we can deduce anything from
+ * INNERVAR = CONSTANT
+ */
+ sub_generate_join_implications(root, equi_key_set, relids,
+ rightop,
+ rinfo->right_sortop,
+ rinfo->right_relids);
+ }
+ }
+
+ /* The same, looking at clauses with OUTERVAR on right */
+ foreach(l, root->right_join_clauses)
+ {
+ RestrictInfo *rinfo = (RestrictInfo *) lfirst(l);
+ Node *rightop = get_rightop(rinfo->clause);
+
+ if (equal(rightop, item1) && rinfo->right_sortop == sortop1)
+ {
+ /*
+ * Match, so find constant member(s) of set and generate
+ * implied INNERVAR = CONSTANT
+ */
+ Node *leftop = get_leftop(rinfo->clause);
+
+ process_implied_const_eq(root, equi_key_set, relids,
+ leftop,
+ rinfo->left_sortop,
+ rinfo->left_relids,
+ false);
+ /*
+ * We can remove explicit tests of this outer-join qual, too,
+ * since we now have tests forcing each of its sides
+ * to the same value.
+ */
+ process_implied_equality(root,
+ leftop, rightop,
+ rinfo->left_sortop, rinfo->right_sortop,
+ rinfo->left_relids, rinfo->right_relids,
+ true);
+ /*
+ * And recurse to see if we can deduce anything from
+ * INNERVAR = CONSTANT
+ */
+ sub_generate_join_implications(root, equi_key_set, relids,
+ leftop,
+ rinfo->left_sortop,
+ rinfo->left_relids);
+ }
+ }
+
+ /*
+ * Only COALESCE(x,y) items can possibly match full joins
+ */
+ if (IsA(item1, CoalesceExpr))
+ {
+ CoalesceExpr *cexpr = (CoalesceExpr *) item1;
+ Node *cfirst;
+ Node *csecond;
+
+ if (list_length(cexpr->args) != 2)
+ return;
+ cfirst = (Node *) linitial(cexpr->args);
+ csecond = (Node *) lsecond(cexpr->args);
+
+ /*
+ * Examine each mergejoinable full-join clause, looking for a
+ * clause of the form "x = y" matching the COALESCE(x,y) expression
+ */
+ foreach(l, root->full_join_clauses)
+ {
+ RestrictInfo *rinfo = (RestrictInfo *) lfirst(l);
+ Node *leftop = get_leftop(rinfo->clause);
+ Node *rightop = get_rightop(rinfo->clause);
+
+ /*
+ * We can assume the COALESCE() inputs are in the same order
+ * as the join clause, since both were automatically generated
+ * in the cases we care about.
+ *
+ * XXX currently this may fail to match in cross-type cases
+ * because the COALESCE will contain typecast operations while
+ * the join clause may not (if there is a cross-type mergejoin
+ * operator available for the two column types).
+ * Is it OK to strip implicit coercions from the COALESCE
+ * arguments? What of the sortops in such cases?
+ */
+ if (equal(leftop, cfirst) &&
+ equal(rightop, csecond) &&
+ rinfo->left_sortop == sortop1 &&
+ rinfo->right_sortop == sortop1)
{
- PathKeyItem *item2 = (PathKeyItem *) lfirst(ptr2);
+ /*
+ * Match, so find constant member(s) of set and generate
+ * implied LEFTVAR = CONSTANT
+ */
+ process_implied_const_eq(root, equi_key_set, relids,
+ leftop,
+ rinfo->left_sortop,
+ rinfo->left_relids,
+ false);
+ /* ... and RIGHTVAR = CONSTANT */
+ process_implied_const_eq(root, equi_key_set, relids,
+ rightop,
+ rinfo->right_sortop,
+ rinfo->right_relids,
+ false);
+ /* ... and remove COALESCE() = CONSTANT */
+ process_implied_const_eq(root, equi_key_set, relids,
+ item1,
+ sortop1,
+ item1_relids,
+ true);
+ /*
+ * We can remove explicit tests of this outer-join qual, too,
+ * since we now have tests forcing each of its sides
+ * to the same value.
+ */
+ process_implied_equality(root,
+ leftop, rightop,
+ rinfo->left_sortop,
+ rinfo->right_sortop,
+ rinfo->left_relids,
+ rinfo->right_relids,
+ true);
+ /*
+ * And recurse to see if we can deduce anything from
+ * LEFTVAR = CONSTANT
+ */
+ sub_generate_join_implications(root, equi_key_set, relids,
+ leftop,
+ rinfo->left_sortop,
+ rinfo->left_relids);
+ /* ... and RIGHTVAR = CONSTANT */
+ sub_generate_join_implications(root, equi_key_set, relids,
+ rightop,
+ rinfo->right_sortop,
+ rinfo->right_relids);
- process_implied_equality(root, item1->key, item2->key,
- item1->sortop, item2->sortop);
}
}
}
}
+/*
+ * process_implied_const_eq
+ * Apply process_implied_equality with the given item and each
+ * pseudoconstant member of equi_key_set.
+ *
+ * equi_key_set and relids are as for generate_outer_join_implications,
+ * the other parameters as for process_implied_equality.
+ */
+static void
+process_implied_const_eq(PlannerInfo *root, List *equi_key_set, Relids *relids,
+ Node *item1, Oid sortop1, Relids item1_relids,
+ bool delete_it)
+{
+ ListCell *l;
+ bool found = false;
+ int i = 0;
+
+ foreach(l, equi_key_set)
+ {
+ PathKeyItem *item2 = (PathKeyItem *) lfirst(l);
+
+ if (bms_is_empty(relids[i]))
+ {
+ process_implied_equality(root,
+ item1, item2->key,
+ sortop1, item2->sortop,
+ item1_relids, NULL,
+ delete_it);
+ found = true;
+ }
+ i++;
+ }
+ /* Caller screwed up if no constants in list */
+ Assert(found);
+}
+
+/*
+ * exprs_known_equal
+ * Detect whether two expressions are known equal due to equijoin clauses.
+ *
+ * Note: does not bother to check for "equal(item1, item2)"; caller must
+ * check that case if it's possible to pass identical items.
+ */
+bool
+exprs_known_equal(PlannerInfo *root, Node *item1, Node *item2)
+{
+ ListCell *cursetlink;
+
+ foreach(cursetlink, root->equi_key_list)
+ {
+ List *curset = (List *) lfirst(cursetlink);
+ bool item1member = false;
+ bool item2member = false;
+ ListCell *ptr;
+
+ foreach(ptr, curset)
+ {
+ PathKeyItem *pitem = (PathKeyItem *) lfirst(ptr);
+
+ if (equal(item1, pitem->key))
+ item1member = true;
+ else if (equal(item2, pitem->key))
+ item2member = true;
+ /* Exit as soon as equality is proven */
+ if (item1member && item2member)
+ return true;
+ }
+ }
+ return false;
+}
+
+
/*
* make_canonical_pathkey
* Given a PathKeyItem, find the equi_key_list subset it is a member of,
* scanning the WHERE clause for equijoin operators.
*/
static List *
-make_canonical_pathkey(Query *root, PathKeyItem *item)
+make_canonical_pathkey(PlannerInfo *root, PathKeyItem *item)
{
- List *cursetlink;
List *newset;
+ ListCell *cursetlink;
foreach(cursetlink, root->equi_key_list)
{
- List *curset = lfirst(cursetlink);
+ List *curset = (List *) lfirst(cursetlink);
- if (member(item, curset))
+ if (list_member(curset, item))
return curset;
}
- newset = makeList1(item);
+ newset = list_make1(item);
root->equi_key_list = lcons(newset, root->equi_key_list);
return newset;
}
* scanning the WHERE clause for equijoin operators.
*/
List *
-canonicalize_pathkeys(Query *root, List *pathkeys)
+canonicalize_pathkeys(PlannerInfo *root, List *pathkeys)
{
List *new_pathkeys = NIL;
- List *i;
+ ListCell *l;
- foreach(i, pathkeys)
+ foreach(l, pathkeys)
{
- List *pathkey = (List *) lfirst(i);
+ List *pathkey = (List *) lfirst(l);
PathKeyItem *item;
List *cpathkey;
* set by definition.
*/
Assert(pathkey != NIL);
- item = (PathKeyItem *) lfirst(pathkey);
+ item = (PathKeyItem *) linitial(pathkey);
cpathkey = make_canonical_pathkey(root, item);
+
/*
- * Eliminate redundant ordering requests --- ORDER BY A,A
- * is the same as ORDER BY A. We want to check this only
- * after we have canonicalized the keys, so that equivalent-key
- * knowledge is used when deciding if an item is redundant.
+ * Eliminate redundant ordering requests --- ORDER BY A,A is the
+ * same as ORDER BY A. We want to check this only after we have
+ * canonicalized the keys, so that equivalent-key knowledge is
+ * used when deciding if an item is redundant.
*/
- if (!ptrMember(cpathkey, new_pathkeys))
- new_pathkeys = lappend(new_pathkeys, cpathkey);
+ new_pathkeys = list_append_unique_ptr(new_pathkeys, cpathkey);
}
return new_pathkeys;
}
+
+/*
+ * count_canonical_peers
+ * Given a PathKeyItem, find the equi_key_list subset it is a member of,
+ * if any. If so, return the number of other members of the set.
+ * If not, return 0 (without actually adding it to our equi_key_list).
+ *
+ * This is a hack to support the rather bogus heuristics in
+ * convert_subquery_pathkeys.
+ */
+static int
+count_canonical_peers(PlannerInfo *root, PathKeyItem *item)
+{
+ ListCell *cursetlink;
+
+ foreach(cursetlink, root->equi_key_list)
+ {
+ List *curset = (List *) lfirst(cursetlink);
+
+ if (list_member(curset, item))
+ return list_length(curset) - 1;
+ }
+ return 0;
+}
+
/****************************************************************************
* PATHKEY COMPARISONS
****************************************************************************/
PathKeysComparison
compare_pathkeys(List *keys1, List *keys2)
{
- List *key1,
+ ListCell *key1,
*key2;
- for (key1 = keys1, key2 = keys2;
- key1 != NIL && key2 != NIL;
- key1 = lnext(key1), key2 = lnext(key2))
+ forboth(key1, keys1, key2, keys2)
{
- List *subkey1 = lfirst(key1);
- List *subkey2 = lfirst(key2);
+ List *subkey1 = (List *) lfirst(key1);
+ List *subkey2 = (List *) lfirst(key2);
/*
- * XXX would like to check that we've been given canonicalized input,
- * but query root not accessible here...
+ * XXX would like to check that we've been given canonicalized
+ * input, but PlannerInfo not accessible here...
*/
#ifdef NOT_USED
- Assert(ptrMember(subkey1, root->equi_key_list));
- Assert(ptrMember(subkey2, root->equi_key_list));
+ Assert(list_member_ptr(root->equi_key_list, subkey1));
+ Assert(list_member_ptr(root->equi_key_list, subkey2));
#endif
/*
* We will never have two subkeys where one is a subset of the
- * other, because of the canonicalization process. Either they
+ * other, because of the canonicalization process. Either they
* are equal or they ain't. Furthermore, we only need pointer
* comparison to detect equality.
*/
* the other list are not NIL --- no pathkey list should ever have a
* NIL sublist.)
*/
- if (key1 == NIL && key2 == NIL)
- return PATHKEYS_EQUAL;
- if (key1 != NIL)
- return PATHKEYS_BETTER1;/* key1 is longer */
- return PATHKEYS_BETTER2; /* key2 is longer */
-}
-
-/*
- * compare_noncanonical_pathkeys
- * Compare two pathkeys to see if they are equivalent, and if not whether
- * one is "better" than the other. This is used when we must compare
- * non-canonicalized pathkeys.
- *
- * A pathkey can be considered better than another if it is a superset:
- * it contains all the keys of the other plus more. For example, either
- * ((A) (B)) or ((A B)) is better than ((A)).
- *
- * Currently, the only user of this routine is grouping_planner(),
- * and it will only pass single-element sublists (from
- * make_pathkeys_for_sortclauses). Therefore we don't have to do the
- * full two-way-subset-inclusion test on each pair of sublists that is
- * implied by the above statement. Instead we just verify they are
- * singleton lists and then do an equal(). This could be improved if
- * necessary.
- */
-PathKeysComparison
-compare_noncanonical_pathkeys(List *keys1, List *keys2)
-{
- List *key1,
- *key2;
-
- for (key1 = keys1, key2 = keys2;
- key1 != NIL && key2 != NIL;
- key1 = lnext(key1), key2 = lnext(key2))
- {
- List *subkey1 = lfirst(key1);
- List *subkey2 = lfirst(key2);
-
- Assert(length(subkey1) == 1);
- Assert(length(subkey2) == 1);
- if (!equal(subkey1, subkey2))
- return PATHKEYS_DIFFERENT; /* no need to keep looking */
- }
-
- /*
- * If we reached the end of only one list, the other is longer and
- * therefore not a subset. (We assume the additional sublist(s) of
- * the other list are not NIL --- no pathkey list should ever have a
- * NIL sublist.)
- */
- if (key1 == NIL && key2 == NIL)
+ if (key1 == NULL && key2 == NULL)
return PATHKEYS_EQUAL;
- if (key1 != NIL)
- return PATHKEYS_BETTER1;/* key1 is longer */
+ if (key1 != NULL)
+ return PATHKEYS_BETTER1; /* key1 is longer */
return PATHKEYS_BETTER2; /* key2 is longer */
}
{
switch (compare_pathkeys(keys1, keys2))
{
- case PATHKEYS_EQUAL:
- case PATHKEYS_BETTER2:
- return true;
- default:
- break;
- }
- return false;
-}
-
-/*
- * noncanonical_pathkeys_contained_in
- * The same, when we don't have canonical pathkeys.
- */
-bool
-noncanonical_pathkeys_contained_in(List *keys1, List *keys2)
-{
- switch (compare_noncanonical_pathkeys(keys1, keys2))
- {
- case PATHKEYS_EQUAL:
- case PATHKEYS_BETTER2:
+ case PATHKEYS_EQUAL:
+ case PATHKEYS_BETTER2:
return true;
default:
break;
CostSelector cost_criterion)
{
Path *matched_path = NULL;
- List *i;
+ ListCell *l;
- foreach(i, paths)
+ foreach(l, paths)
{
- Path *path = (Path *) lfirst(i);
+ Path *path = (Path *) lfirst(l);
/*
* Since cost comparison is a lot cheaper than pathkey comparison,
double fraction)
{
Path *matched_path = NULL;
- List *i;
+ ListCell *l;
- foreach(i, paths)
+ foreach(l, paths)
{
- Path *path = (Path *) lfirst(i);
+ Path *path = (Path *) lfirst(l);
/*
* Since cost comparison is a lot cheaper than pathkey comparison,
*
* If 'scandir' is BackwardScanDirection, attempt to build pathkeys
* representing a backwards scan of the index. Return NIL if can't do it.
+ *
+ * We generate the full pathkeys list whether or not all are useful for the
+ * current query. Caller should do truncate_useless_pathkeys().
*/
List *
-build_index_pathkeys(Query *root,
- RelOptInfo *rel,
+build_index_pathkeys(PlannerInfo *root,
IndexOptInfo *index,
ScanDirection scandir)
{
List *retval = NIL;
int *indexkeys = index->indexkeys;
Oid *ordering = index->ordering;
- PathKeyItem *item;
- Oid sortop;
-
- if (!indexkeys || indexkeys[0] == 0 ||
- !ordering || ordering[0] == InvalidOid)
- return NIL; /* unordered index? */
+ ListCell *indexprs_item = list_head(index->indexprs);
- if (index->indproc)
+ while (*ordering != InvalidOid)
{
- /* Functional index: build a representation of the function call */
- Func *funcnode = makeNode(Func);
- List *funcargs = NIL;
-
- funcnode->funcid = index->indproc;
- funcnode->functype = get_func_rettype(index->indproc);
- funcnode->func_fcache = NULL;
-
- while (*indexkeys != 0)
- {
- funcargs = lappend(funcargs,
- find_indexkey_var(root, rel, *indexkeys));
- indexkeys++;
- }
+ PathKeyItem *item;
+ Oid sortop;
+ Node *indexkey;
+ List *cpathkey;
sortop = *ordering;
if (ScanDirectionIsBackward(scandir))
{
sortop = get_commutator(sortop);
if (sortop == InvalidOid)
- return NIL; /* oops, no reverse sort operator? */
+ break; /* oops, no reverse sort operator? */
}
- /* Make a one-sublist pathkeys list for the function expression */
- item = makePathKeyItem((Node *) make_funcclause(funcnode, funcargs),
- sortop);
- retval = lcons(make_canonical_pathkey(root, item), NIL);
- }
- else
- {
- /* Normal non-functional index */
- while (*indexkeys != 0 && *ordering != InvalidOid)
+ if (*indexkeys != 0)
{
- Var *relvar = find_indexkey_var(root, rel, *indexkeys);
- List *cpathkey;
+ /* simple index column */
+ indexkey = (Node *) find_indexkey_var(root, index->rel,
+ *indexkeys);
+ }
+ else
+ {
+ /* expression --- assume we need not copy it */
+ if (indexprs_item == NULL)
+ elog(ERROR, "wrong number of index expressions");
+ indexkey = (Node *) lfirst(indexprs_item);
+ indexprs_item = lnext(indexprs_item);
+ }
- sortop = *ordering;
- if (ScanDirectionIsBackward(scandir))
- {
- sortop = get_commutator(sortop);
- if (sortop == InvalidOid)
- break; /* oops, no reverse sort operator? */
- }
+ /* OK, make a sublist for this sort key */
+ item = makePathKeyItem(indexkey, sortop, true);
+ cpathkey = make_canonical_pathkey(root, item);
- /* OK, make a sublist for this sort key */
- item = makePathKeyItem((Node *) relvar, sortop);
- cpathkey = make_canonical_pathkey(root, item);
- /*
- * Eliminate redundant ordering info; could happen if query
- * is such that index keys are equijoined...
- */
- if (!ptrMember(cpathkey, retval))
- retval = lappend(retval, cpathkey);
- indexkeys++;
- ordering++;
- }
+ /*
+ * Eliminate redundant ordering info; could happen if query is
+ * such that index keys are equijoined...
+ */
+ retval = list_append_unique_ptr(retval, cpathkey);
+
+ indexkeys++;
+ ordering++;
}
return retval;
* gin up a Var node the hard way.
*/
static Var *
-find_indexkey_var(Query *root, RelOptInfo *rel, AttrNumber varattno)
+find_indexkey_var(PlannerInfo *root, RelOptInfo *rel, AttrNumber varattno)
{
- List *temp;
- int relid;
+ ListCell *temp;
+ Index relid;
Oid reloid,
vartypeid;
int32 type_mod;
- foreach(temp, rel->targetlist)
+ foreach(temp, rel->reltargetlist)
{
- Var *tle_var = get_expr(lfirst(temp));
+ Var *var = (Var *) lfirst(temp);
- if (IsA(tle_var, Var) &&tle_var->varattno == varattno)
- return tle_var;
+ if (IsA(var, Var) &&
+ var->varattno == varattno)
+ return var;
}
- relid = lfirsti(rel->relids);
- reloid = getrelid(relid, root->rtable);
- vartypeid = get_atttype(reloid, varattno);
- type_mod = get_atttypmod(reloid, varattno);
+ relid = rel->relid;
+ reloid = getrelid(relid, root->parse->rtable);
+ get_atttypetypmod(reloid, varattno, &vartypeid, &type_mod);
return makeVar(relid, varattno, vartypeid, type_mod, 0);
}
+/*
+ * convert_subquery_pathkeys
+ * Build a pathkeys list that describes the ordering of a subquery's
+ * result, in the terms of the outer query. This is essentially a
+ * task of conversion.
+ *
+ * 'rel': outer query's RelOptInfo for the subquery relation.
+ * 'subquery_pathkeys': the subquery's output pathkeys, in its terms.
+ *
+ * It is not necessary for caller to do truncate_useless_pathkeys(),
+ * because we select keys in a way that takes usefulness of the keys into
+ * account.
+ */
+List *
+convert_subquery_pathkeys(PlannerInfo *root, RelOptInfo *rel,
+ List *subquery_pathkeys)
+{
+ List *retval = NIL;
+ int retvallen = 0;
+ int outer_query_keys = list_length(root->query_pathkeys);
+ List *sub_tlist = rel->subplan->targetlist;
+ ListCell *i;
+
+ foreach(i, subquery_pathkeys)
+ {
+ List *sub_pathkey = (List *) lfirst(i);
+ ListCell *j;
+ PathKeyItem *best_item = NULL;
+ int best_score = 0;
+ List *cpathkey;
+
+ /*
+ * The sub_pathkey could contain multiple elements (representing
+ * knowledge that multiple items are effectively equal). Each
+ * element might match none, one, or more of the output columns
+ * that are visible to the outer query. This means we may have
+ * multiple possible representations of the sub_pathkey in the
+ * context of the outer query. Ideally we would generate them all
+ * and put them all into a pathkey list of the outer query,
+ * thereby propagating equality knowledge up to the outer query.
+ * Right now we cannot do so, because the outer query's canonical
+ * pathkey sets are already frozen when this is called. Instead
+ * we prefer the one that has the highest "score" (number of
+ * canonical pathkey peers, plus one if it matches the outer
+ * query_pathkeys). This is the most likely to be useful in the
+ * outer query.
+ */
+ foreach(j, sub_pathkey)
+ {
+ PathKeyItem *sub_item = (PathKeyItem *) lfirst(j);
+ Node *sub_key = sub_item->key;
+ ListCell *k;
+
+ foreach(k, sub_tlist)
+ {
+ TargetEntry *tle = (TargetEntry *) lfirst(k);
+
+ if (!tle->resjunk &&
+ equal(tle->expr, sub_key))
+ {
+ /* Found a representation for this sub_key */
+ Var *outer_var;
+ PathKeyItem *outer_item;
+ int score;
+
+ outer_var = makeVar(rel->relid,
+ tle->resno,
+ exprType((Node *) tle->expr),
+ exprTypmod((Node *) tle->expr),
+ 0);
+ outer_item = makePathKeyItem((Node *) outer_var,
+ sub_item->sortop,
+ true);
+ /* score = # of mergejoin peers */
+ score = count_canonical_peers(root, outer_item);
+ /* +1 if it matches the proper query_pathkeys item */
+ if (retvallen < outer_query_keys &&
+ list_member(list_nth(root->query_pathkeys, retvallen), outer_item))
+ score++;
+ if (score > best_score)
+ {
+ best_item = outer_item;
+ best_score = score;
+ }
+ }
+ }
+ }
+
+ /*
+ * If we couldn't find a representation of this sub_pathkey, we're
+ * done (we can't use the ones to its right, either).
+ */
+ if (!best_item)
+ break;
+
+ /* Canonicalize the chosen item (we did not before) */
+ cpathkey = make_canonical_pathkey(root, best_item);
+
+ /*
+ * Eliminate redundant ordering info; could happen if outer query
+ * equijoins subquery keys...
+ */
+ if (!list_member_ptr(retval, cpathkey))
+ {
+ retval = lappend(retval, cpathkey);
+ retvallen++;
+ }
+ }
+
+ return retval;
+}
+
/*
* build_join_pathkeys
* Build the path keys for a join relation constructed by mergejoin or
* vars they were joined with; furthermore, it doesn't matter what kind
* of join algorithm is actually used.
*
+ * EXCEPTION: in a FULL or RIGHT join, we cannot treat the result as
+ * having the outer path's path keys, because null lefthand rows may be
+ * inserted at random points. It must be treated as unsorted.
+ *
* 'joinrel' is the join relation that paths are being formed for
+ * 'jointype' is the join type (inner, left, full, etc)
* 'outer_pathkeys' is the list of the current outer path's path keys
*
* Returns the list of new path keys.
*/
List *
-build_join_pathkeys(Query *root,
+build_join_pathkeys(PlannerInfo *root,
RelOptInfo *joinrel,
+ JoinType jointype,
List *outer_pathkeys)
{
+ if (jointype == JOIN_FULL || jointype == JOIN_RIGHT)
+ return NIL;
/*
* This used to be quite a complex bit of code, but now that all
List *tlist)
{
List *pathkeys = NIL;
- List *i;
+ ListCell *l;
- foreach(i, sortclauses)
+ foreach(l, sortclauses)
{
- SortClause *sortcl = (SortClause *) lfirst(i);
+ SortClause *sortcl = (SortClause *) lfirst(l);
Node *sortkey;
PathKeyItem *pathkey;
sortkey = get_sortgroupclause_expr(sortcl, tlist);
- pathkey = makePathKeyItem(sortkey, sortcl->sortop);
+ pathkey = makePathKeyItem(sortkey, sortcl->sortop, true);
/*
* The pathkey becomes a one-element sublist, for now;
* canonicalize_pathkeys() might replace it with a longer sublist
* later.
*/
- pathkeys = lappend(pathkeys, lcons(pathkey, NIL));
+ pathkeys = lappend(pathkeys, list_make1(pathkey));
}
return pathkeys;
}
*
* RestrictInfo contains fields in which we may cache the result
* of looking up the canonical pathkeys for the left and right sides
- * of the mergeclause. (Note that in normal cases they will be the
+ * of the mergeclause. (Note that in normal cases they will be the
* same, but not if the mergeclause appears above an OUTER JOIN.)
* This is a worthwhile savings because these routines will be invoked
* many times when dealing with a many-relation query.
+ *
+ * We have to be careful that the cached values are palloc'd in the same
+ * context the RestrictInfo node itself is in. This is not currently a
+ * problem for normal planning, but it is an issue for GEQO planning.
*/
-static void
-cache_mergeclause_pathkeys(Query *root, RestrictInfo *restrictinfo)
+void
+cache_mergeclause_pathkeys(PlannerInfo *root, RestrictInfo *restrictinfo)
{
Node *key;
PathKeyItem *item;
+ MemoryContext oldcontext;
Assert(restrictinfo->mergejoinoperator != InvalidOid);
if (restrictinfo->left_pathkey == NIL)
{
- key = (Node *) get_leftop(restrictinfo->clause);
- item = makePathKeyItem(key, restrictinfo->left_sortop);
+ oldcontext = MemoryContextSwitchTo(GetMemoryChunkContext(restrictinfo));
+ key = get_leftop(restrictinfo->clause);
+ item = makePathKeyItem(key, restrictinfo->left_sortop, false);
restrictinfo->left_pathkey = make_canonical_pathkey(root, item);
+ MemoryContextSwitchTo(oldcontext);
}
if (restrictinfo->right_pathkey == NIL)
{
- key = (Node *) get_rightop(restrictinfo->clause);
- item = makePathKeyItem(key, restrictinfo->right_sortop);
+ oldcontext = MemoryContextSwitchTo(GetMemoryChunkContext(restrictinfo));
+ key = get_rightop(restrictinfo->clause);
+ item = makePathKeyItem(key, restrictinfo->right_sortop, false);
restrictinfo->right_pathkey = make_canonical_pathkey(root, item);
+ MemoryContextSwitchTo(oldcontext);
}
}
* of the join.
*/
List *
-find_mergeclauses_for_pathkeys(Query *root,
+find_mergeclauses_for_pathkeys(PlannerInfo *root,
List *pathkeys,
List *restrictinfos)
{
List *mergeclauses = NIL;
- List *i;
+ ListCell *i;
+
+ /* make sure we have pathkeys cached in the clauses */
+ foreach(i, restrictinfos)
+ {
+ RestrictInfo *restrictinfo = (RestrictInfo *) lfirst(i);
+
+ cache_mergeclause_pathkeys(root, restrictinfo);
+ }
foreach(i, pathkeys)
{
- List *pathkey = lfirst(i);
- RestrictInfo *matched_restrictinfo = NULL;
- List *j;
+ List *pathkey = (List *) lfirst(i);
+ List *matched_restrictinfos = NIL;
+ ListCell *j;
/*
* We can match a pathkey against either left or right side of any
- * mergejoin clause we haven't used yet. For the moment we use a
- * dumb "greedy" algorithm with no backtracking. Is it worth being
- * any smarter to make a longer list of usable mergeclauses?
- * Probably not.
+ * mergejoin clause. (We examine both sides since we aren't told
+ * if the given pathkeys are for inner or outer input path; no
+ * confusion is possible.) Furthermore, if there are multiple
+ * matching clauses, take them all. In plain inner-join scenarios
+ * we expect only one match, because redundant-mergeclause
+ * elimination will have removed any redundant mergeclauses from
+ * the input list. However, in outer-join scenarios there might be
+ * multiple matches. An example is
+ *
+ * select * from a full join b on a.v1 = b.v1 and a.v2 = b.v2 and
+ * a.v1 = b.v2;
+ *
+ * Given the pathkeys ((a.v1), (a.v2)) it is okay to return all three
+ * clauses (in the order a.v1=b.v1, a.v1=b.v2, a.v2=b.v2) and
+ * indeed we *must* do so or we will be unable to form a valid
+ * plan.
*/
foreach(j, restrictinfos)
{
- RestrictInfo *restrictinfo = lfirst(j);
+ RestrictInfo *restrictinfo = (RestrictInfo *) lfirst(j);
- cache_mergeclause_pathkeys(root, restrictinfo);
/*
- * We can compare canonical pathkey sublists by simple
- * pointer equality; see compare_pathkeys.
+ * We can compare canonical pathkey sublists by simple pointer
+ * equality; see compare_pathkeys.
*/
if ((pathkey == restrictinfo->left_pathkey ||
pathkey == restrictinfo->right_pathkey) &&
- !ptrMember(restrictinfo, mergeclauses))
+ !list_member_ptr(mergeclauses, restrictinfo))
{
- matched_restrictinfo = restrictinfo;
- break;
+ matched_restrictinfos = lappend(matched_restrictinfos,
+ restrictinfo);
}
}
* sort-key positions in the pathkeys are useless. (But we can
* still mergejoin if we found at least one mergeclause.)
*/
- if (!matched_restrictinfo)
+ if (matched_restrictinfos == NIL)
break;
/*
- * If we did find a usable mergeclause for this sort-key position,
- * add it to result list.
+ * If we did find usable mergeclause(s) for this sort-key
+ * position, add them to result list.
*/
- mergeclauses = lappend(mergeclauses, matched_restrictinfo);
+ mergeclauses = list_concat(mergeclauses, matched_restrictinfos);
}
return mergeclauses;
* just make the keys, eh?
*/
List *
-make_pathkeys_for_mergeclauses(Query *root,
+make_pathkeys_for_mergeclauses(PlannerInfo *root,
List *mergeclauses,
RelOptInfo *rel)
{
List *pathkeys = NIL;
- List *i;
+ ListCell *l;
- foreach(i, mergeclauses)
+ foreach(l, mergeclauses)
{
- RestrictInfo *restrictinfo = (RestrictInfo *) lfirst(i);
- Node *key;
+ RestrictInfo *restrictinfo = (RestrictInfo *) lfirst(l);
List *pathkey;
cache_mergeclause_pathkeys(root, restrictinfo);
- key = (Node *) get_leftop(restrictinfo->clause);
- if (IsA(key, Var) && intMember(((Var *) key)->varno, rel->relids))
+ if (bms_is_subset(restrictinfo->left_relids, rel->relids))
{
/* Rel is left side of mergeclause */
pathkey = restrictinfo->left_pathkey;
}
+ else if (bms_is_subset(restrictinfo->right_relids, rel->relids))
+ {
+ /* Rel is right side of mergeclause */
+ pathkey = restrictinfo->right_pathkey;
+ }
else
{
- key = (Node *) get_rightop(restrictinfo->clause);
- if (IsA(key, Var) && intMember(((Var *) key)->varno, rel->relids))
- {
- /* Rel is right side of mergeclause */
- pathkey = restrictinfo->right_pathkey;
- }
- else
- {
- elog(ERROR, "make_pathkeys_for_mergeclauses: can't identify which side of mergeclause to use");
- pathkey = NIL; /* keep compiler quiet */
- }
+ elog(ERROR, "could not identify which side of mergeclause to use");
+ pathkey = NIL; /* keep compiler quiet */
}
/*
- * When we are given multiple merge clauses, it's possible that some
- * clauses refer to the same vars as earlier clauses. There's no
- * reason for us to specify sort keys like (A,B,A) when (A,B) will
- * do --- and adding redundant sort keys makes add_path think that
- * this sort order is different from ones that are really the same,
- * so don't do it. Since we now have a canonicalized pathkey,
- * a simple ptrMember test is sufficient to detect redundant keys.
+ * When we are given multiple merge clauses, it's possible that
+ * some clauses refer to the same vars as earlier clauses. There's
+ * no reason for us to specify sort keys like (A,B,A) when (A,B)
+ * will do --- and adding redundant sort keys makes add_path think
+ * that this sort order is different from ones that are really the
+ * same, so don't do it. Since we now have a canonicalized
+ * pathkey, a simple ptrMember test is sufficient to detect
+ * redundant keys.
*/
- if (!ptrMember(pathkey, pathkeys))
- pathkeys = lappend(pathkeys, pathkey);
+ pathkeys = list_append_unique_ptr(pathkeys, pathkey);
}
return pathkeys;
/*
* pathkeys_useful_for_merging
* Count the number of pathkeys that may be useful for mergejoins
- * above the given relation (by looking at its joininfo lists).
+ * above the given relation (by looking at its joininfo list).
*
* We consider a pathkey potentially useful if it corresponds to the merge
* ordering of either side of any joinclause for the rel. This might be
- * overoptimistic, since joinclauses that appear in different join lists
+ * overoptimistic, since joinclauses that require different other relations
* might never be usable at the same time, but trying to be exact is likely
* to be more trouble than it's worth.
*/
int
-pathkeys_useful_for_merging(Query *root, RelOptInfo *rel, List *pathkeys)
+pathkeys_useful_for_merging(PlannerInfo *root, RelOptInfo *rel, List *pathkeys)
{
int useful = 0;
- List *i;
+ ListCell *i;
foreach(i, pathkeys)
{
- List *pathkey = lfirst(i);
+ List *pathkey = (List *) lfirst(i);
bool matched = false;
- List *j;
+ ListCell *j;
foreach(j, rel->joininfo)
{
- JoinInfo *joininfo = (JoinInfo *) lfirst(j);
- List *k;
-
- foreach(k, joininfo->jinfo_restrictinfo)
- {
- RestrictInfo *restrictinfo = (RestrictInfo *) lfirst(k);
+ RestrictInfo *restrictinfo = (RestrictInfo *) lfirst(j);
- if (restrictinfo->mergejoinoperator == InvalidOid)
- continue;
- cache_mergeclause_pathkeys(root, restrictinfo);
- /*
- * We can compare canonical pathkey sublists by simple
- * pointer equality; see compare_pathkeys.
- */
- if (pathkey == restrictinfo->left_pathkey ||
- pathkey == restrictinfo->right_pathkey)
- {
- matched = true;
- break;
- }
- }
+ if (restrictinfo->mergejoinoperator == InvalidOid)
+ continue;
+ cache_mergeclause_pathkeys(root, restrictinfo);
- if (matched)
+ /*
+ * We can compare canonical pathkey sublists by simple
+ * pointer equality; see compare_pathkeys.
+ */
+ if (pathkey == restrictinfo->left_pathkey ||
+ pathkey == restrictinfo->right_pathkey)
+ {
+ matched = true;
break;
+ }
}
/*
*
* Unlike merge pathkeys, this is an all-or-nothing affair: it does us
* no good to order by just the first key(s) of the requested ordering.
- * So the result is always either 0 or length(root->query_pathkeys).
+ * So the result is always either 0 or list_length(root->query_pathkeys).
*/
int
-pathkeys_useful_for_ordering(Query *root, List *pathkeys)
+pathkeys_useful_for_ordering(PlannerInfo *root, List *pathkeys)
{
if (root->query_pathkeys == NIL)
return 0; /* no special ordering requested */
if (pathkeys_contained_in(root->query_pathkeys, pathkeys))
{
/* It's useful ... or at least the first N keys are */
- return length(root->query_pathkeys);
+ return list_length(root->query_pathkeys);
}
return 0; /* path ordering not useful */
* Shorten the given pathkey list to just the useful pathkeys.
*/
List *
-truncate_useless_pathkeys(Query *root,
+truncate_useless_pathkeys(PlannerInfo *root,
RelOptInfo *rel,
List *pathkeys)
{
nuseful2 = pathkeys_useful_for_ordering(root, pathkeys);
if (nuseful2 > nuseful)
nuseful = nuseful2;
- /* Note: not safe to modify input list destructively, but we can avoid
+
+ /*
+ * Note: not safe to modify input list destructively, but we can avoid
* copying the list if we're not actually going to change it
*/
- if (nuseful == length(pathkeys))
+ if (nuseful == list_length(pathkeys))
return pathkeys;
else
- return ltruncate(nuseful, listCopy(pathkeys));
+ return list_truncate(list_copy(pathkeys), nuseful);
}
projects / postgresql / blobdiff