*
* joinrels.cpp
* Routines to determine which relations should be joined
*
* Portions Copyright (c) 2020 Huawei Technologies Co.,Ltd.
* Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/gausskernel/optimizer/path/joinrels.cpp
*
* -------------------------------------------------------------------------
*/
#include "postgres.h"
#include "knl/knl_variable.h"
#include "miscadmin.h"
#include "optimizer/dataskew.h"
#include "optimizer/joininfo.h"
#include "optimizer/pathnode.h"
#include "optimizer/paths.h"
#include "optimizer/planner.h"
#include "utils/memutils.h"
#include "utils/guc.h"
#ifdef PGXC
#include "pgxc/pgxc.h"
#endif
#ifdef STREAMPLAN
#include "optimizer/streamplan.h"
#endif
static void make_rels_by_clause_joins(PlannerInfo* root, RelOptInfo* old_rel, ListCell* other_rels);
static void make_rels_by_clauseless_joins(PlannerInfo* root, RelOptInfo* old_rel, ListCell* other_rels);
static bool has_join_restriction(PlannerInfo* root, RelOptInfo* rel);
static bool has_legal_joinclause(PlannerInfo* root, RelOptInfo* rel);
static bool is_dummy_rel(const RelOptInfo* rel);
static void mark_dummy_rel(RelOptInfo* rel);
static bool restriction_is_constant_false(List* restrictlist, bool only_pushed_down);
* join_search_one_level
* Consider ways to produce join relations containing exactly 'level'
* jointree items. (This is one step of the dynamic-programming method
* embodied in standard_join_search.) Join rel nodes for each feasible
* combination of lower-level rels are created and returned in a list.
* Implementation paths are created for each such joinrel, too.
*
* level: level of rels we want to make this time
* root->join_rel_level[j], 1 <= j < level, is a list of rels containing j items
*
* The result is returned in root->join_rel_level[level].
*/
void join_search_one_level(PlannerInfo* root, int level)
{
List** joinrels = root->join_rel_level;
ListCell* r = NULL;
int k;
AssertEreport(joinrels[level] == NIL, MOD_OPT_JOIN, "Join rel list is NIL");
root->join_cur_level = level;
* First, consider left-sided and right-sided plans, in which rels of
* exactly level-1 member relations are joined against initial relations.
* We prefer to join using join clauses, but if we find a rel of level-1
* members that has no join clauses, we will generate Cartesian-product
* joins against all initial rels not already contained in it.
*/
foreach (r, joinrels[level - 1]) {
RelOptInfo* old_rel = (RelOptInfo*)lfirst(r);
bool isTrue = old_rel->joininfo != NIL || old_rel->has_eclass_joins
|| has_join_restriction(root, old_rel);
if (isTrue) {
* There are join clauses or join order restrictions relevant to
* this rel, so consider joins between this rel and (only) those
* initial rels it is linked to by a clause or restriction.
*
* At level 2 this condition is symmetric, so there is no need to
* look at initial rels before this one in the list; we already
* considered such joins when we were at the earlier rel. (The
* mirror-image joins are handled automatically by make_join_rel.)
* In later passes (level > 2), we join rels of the previous level
* to each initial rel they don't already include but have a join
* clause or restriction with.
*/
ListCell* other_rels = NULL;
if (level == 2)
other_rels = lnext(r);
else
other_rels = list_head(joinrels[1]);
make_rels_by_clause_joins(root, old_rel, other_rels);
} else {
* Oops, we have a relation that is not joined to any other
* relation, either directly or by join-order restrictions.
* Cartesian product time.
*
* We consider a cartesian product with each not-already-included
* initial rel, whether it has other join clauses or not. At
* level 2, if there are two or more clauseless initial rels, we
* will redundantly consider joining them in both directions; but
* such cases aren't common enough to justify adding complexity to
* avoid the duplicated effort.
*/
make_rels_by_clauseless_joins(root, old_rel, list_head(joinrels[1]));
}
}
* Now, consider "bushy plans" in which relations of k initial rels are
* joined to relations of level-k initial rels, for 2 <= k <= level-2.
*
* We only consider bushy-plan joins for pairs of rels where there is a
* suitable join clause (or join order restriction), in order to avoid
* unreasonable growth of planning time.
*/
for (k = 2;; k++) {
int other_level = level - k;
* Since make_join_rel(x, y) handles both x,y and y,x cases, we only
* need to go as far as the halfway point.
*/
if (k > other_level)
break;
foreach (r, joinrels[k]) {
RelOptInfo* old_rel = (RelOptInfo*)lfirst(r);
ListCell* other_rels = NULL;
ListCell* r2 = NULL;
* We can ignore relations without join clauses here, unless they
* participate in join-order restrictions --- then we might have
* to force a bushy join plan.
*/
if (old_rel->joininfo == NIL && !old_rel->has_eclass_joins && !has_join_restriction(root, old_rel))
continue;
if (k == other_level)
other_rels = lnext(r);
else
other_rels = list_head(joinrels[other_level]);
for_each_cell(r2, other_rels)
{
RelOptInfo* new_rel = (RelOptInfo*)lfirst(r2);
if (!bms_overlap(old_rel->relids, new_rel->relids)) {
* OK, we can build a rel of the right level from this
* pair of rels. Do so if there is at least one relevant
* join clause or join order restriction.
*/
if (have_relevant_joinclause(root, old_rel, new_rel) ||
have_join_order_restriction(root, old_rel, new_rel)) {
(void)make_join_rel(root, old_rel, new_rel);
}
}
}
}
}
* Last-ditch effort: if we failed to find any usable joins so far, force
* a set of cartesian-product joins to be generated. This handles the
* special case where all the available rels have join clauses but we
* cannot use any of those clauses yet. This can only happen when we are
* considering a join sub-problem (a sub-joinlist) and all the rels in the
* sub-problem have only join clauses with rels outside the sub-problem.
* An example is
*
* SELECT ... FROM a INNER JOIN b ON TRUE, c, d, ...
* WHERE a.w = c.x and b.y = d.z;
*
* If the "a INNER JOIN b" sub-problem does not get flattened into the
* upper level, we must be willing to make a cartesian join of a and b;
* but the code above will not have done so, because it thought that both
* a and b have joinclauses. We consider only left-sided and right-sided
* cartesian joins in this case (no bushy).
* ----------
*/
if (joinrels[level] == NIL) {
* This loop is just like the first one, except we always
* call make_rels_by_clauseless_joins().
*/
foreach (r, joinrels[level - 1]) {
RelOptInfo* old_rel = (RelOptInfo*)lfirst(r);
make_rels_by_clauseless_joins(root, old_rel, list_head(joinrels[1]));
}
* When special joins are involved, there may be no legal way
* to make an N-way join for some values of N. For example consider
*
* SELECT ... FROM t1 WHERE
* x IN (SELECT ... FROM t2,t3 WHERE ...) AND
* y IN (SELECT ... FROM t4,t5 WHERE ...)
*
* We will flatten this query to a 5-way join problem, but there are
* no 4-way joins that join_is_legal() will consider legal. We have
* to accept failure at level 4 and go on to discover a workable
* bushy plan at level 5.
*
* However, if there are no special joins then join_is_legal() should
* never fail, and so the following sanity check is useful.
* ----------
*/
if (joinrels[level] == NIL && root->join_info_list == NIL &&
root->lateral_info_list == NIL)
ereport(ERROR,
(errmodule(MOD_OPT),
errcode(ERRCODE_OPTIMIZER_INCONSISTENT_STATE),
(errmsg("failed to build any %d-way joins", level))));
}
}
* make_rels_by_clause_joins
* Build joins between the given relation 'old_rel' and other relations
* that participate in join clauses that 'old_rel' also participates in
* (or participate in join-order restrictions with it).
* The join rels are returned in root->join_rel_level[join_cur_level].
*
* Note: at levels above 2 we will generate the same joined relation in
* multiple ways --- for example (a join b) join c is the same RelOptInfo as
* (b join c) join a, though the second case will add a different set of Paths
* to it. This is the reason for using the join_rel_level mechanism, which
* automatically ensures that each new joinrel is only added to the list once.
*
* 'old_rel' is the relation entry for the relation to be joined
* 'other_rels': the first cell in a linked list containing the other
* rels to be considered for joining
*
* Currently, this is only used with initial rels in other_rels, but it
* will work for joining to joinrels too.
*/
static void make_rels_by_clause_joins(PlannerInfo* root, RelOptInfo* old_rel, ListCell* other_rels)
{
ListCell* l = NULL;
for_each_cell(l, other_rels)
{
RelOptInfo* other_rel = (RelOptInfo*)lfirst(l);
if (!bms_overlap(old_rel->relids, other_rel->relids) &&
(have_relevant_joinclause(root, old_rel, other_rel) ||
have_join_order_restriction(root, old_rel, other_rel))) {
(void)make_join_rel(root, old_rel, other_rel);
}
}
}
* make_rels_by_clauseless_joins
* Given a relation 'old_rel' and a list of other relations
* 'other_rels', create a join relation between 'old_rel' and each
* member of 'other_rels' that isn't already included in 'old_rel'.
* The join rels are returned in root->join_rel_level[join_cur_level].
*
* 'old_rel' is the relation entry for the relation to be joined
* 'other_rels': the first cell of a linked list containing the
* other rels to be considered for joining
*
* Currently, this is only used with initial rels in other_rels, but it would
* work for joining to joinrels too.
*/
static void make_rels_by_clauseless_joins(PlannerInfo* root, RelOptInfo* old_rel, ListCell* other_rels)
{
ListCell* l = NULL;
for_each_cell(l, other_rels)
{
RelOptInfo* other_rel = (RelOptInfo*)lfirst(l);
if (!bms_overlap(other_rel->relids, old_rel->relids)) {
(void)make_join_rel(root, old_rel, other_rel);
}
}
}
* join_is_legal
* Determine whether a proposed join is legal given the query's
* join order constraints; and if it is, determine the join type.
*
* Caller must supply not only the two rels, but the union of their relids.
* (We could simplify the API by computing joinrelids locally, but this
* would be redundant work in the normal path through make_join_rel.)
*
* On success, *sjinfo_p is set to NULL if this is to be a plain inner join,
* else it's set to point to the associated SpecialJoinInfo node. Also,
* *reversed_p is set TRUE if the given relations need to be swapped to
* match the SpecialJoinInfo node.
*/
static bool join_is_legal(PlannerInfo* root, RelOptInfo* rel1, RelOptInfo* rel2, Relids joinrelids,
SpecialJoinInfo** sjinfo_p, bool* reversed_p, bool* straight_join_p)
{
SpecialJoinInfo* match_sjinfo = NULL;
bool reversed = false;
bool straight_join = false;
bool unique_exchange = false;
bool must_be_leftjoin = false;
bool lateral_fwd = false;
bool lateral_rev = false;
ListCell* l = NULL;
* Ensure output params are set on failure return. This is just to
* suppress uninitialized-variable warnings from overly anal compilers.
*/
*sjinfo_p = NULL;
*reversed_p = false;
*straight_join_p = false;
* If we have any special joins, the proposed join might be illegal; and
* in any case we have to determine its join type. Scan the join info
* list for matches and conflicts.
*/
foreach (l, root->join_info_list) {
SpecialJoinInfo* sjinfo = (SpecialJoinInfo*)lfirst(l);
if (sjinfo->is_straight_join) {
straight_join = true;
}
* This special join is not relevant unless its RHS overlaps the
* proposed join. (Check this first as a fast path for dismissing
* most irrelevant SJs quickly.)
*/
if (!bms_overlap(sjinfo->min_righthand, joinrelids))
continue;
* Also, not relevant if proposed join is fully contained within RHS
* (ie, we're still building up the RHS).
*/
if (bms_is_subset(joinrelids, sjinfo->min_righthand))
continue;
* Also, not relevant if SJ is already done within either input.
*/
if (bms_is_subset(sjinfo->min_lefthand, rel1->relids) && bms_is_subset(sjinfo->min_righthand, rel1->relids))
continue;
if (bms_is_subset(sjinfo->min_lefthand, rel2->relids) && bms_is_subset(sjinfo->min_righthand, rel2->relids))
continue;
* If it's a semijoin and we already joined the RHS to any other rels
* within either input, then we must have unique-ified the RHS at that
* point (see below). Therefore the semijoin is no longer relevant in
* this join path.
*/
if (sjinfo->jointype == JOIN_SEMI) {
if (bms_is_subset(sjinfo->syn_righthand, rel1->relids) && !bms_equal(sjinfo->syn_righthand, rel1->relids))
continue;
if (bms_is_subset(sjinfo->syn_righthand, rel2->relids) && !bms_equal(sjinfo->syn_righthand, rel2->relids))
continue;
}
* If one input contains min_lefthand and the other contains
* min_righthand, then we can perform the SJ at this join.
*
* Reject if we get matches to more than one SJ; that implies we're
* considering something that's not really valid.
*/
if (bms_is_subset(sjinfo->min_lefthand, rel1->relids) && bms_is_subset(sjinfo->min_righthand, rel2->relids)) {
if (match_sjinfo != NULL)
return false;
match_sjinfo = sjinfo;
reversed = false;
if (sjinfo->jointype == JOIN_SEMI && bms_equal(sjinfo->syn_righthand, rel2->relids) &&
create_unique_path(root, rel2, (Path*)linitial(rel2->cheapest_total_path), sjinfo) != NULL) {
unique_exchange = true;
}
} else if (bms_is_subset(sjinfo->min_lefthand, rel2->relids) &&
bms_is_subset(sjinfo->min_righthand, rel1->relids)) {
if (match_sjinfo != NULL)
return false;
match_sjinfo = sjinfo;
reversed = true;
if (sjinfo->jointype == JOIN_SEMI && bms_equal(sjinfo->syn_righthand, rel1->relids) &&
create_unique_path(root, rel1, (Path*)linitial(rel1->cheapest_total_path), sjinfo) != NULL) {
unique_exchange = true;
}
} else if (sjinfo->jointype == JOIN_SEMI && bms_equal(sjinfo->syn_righthand, rel2->relids) &&
((Path*)linitial(rel2->cheapest_total_path))->param_info == NULL &&
create_unique_path(root, rel2, (Path*)linitial(rel2->cheapest_total_path), sjinfo) != NULL) {
* For a semijoin, we can join the RHS to anything else by
* unique-ifying the RHS (if the RHS can be unique-ified).
* We will only get here if we have the full RHS but less
* than min_lefthand on the LHS.
*
* The reason to consider such a join path is exemplified by
* SELECT ... FROM a,b WHERE (a.x,b.y) IN (SELECT c1,c2 FROM c)
* If we insist on doing this as a semijoin we will first have
* to form the cartesian product of A*B. But if we unique-ify
* C then the semijoin becomes a plain innerjoin and we can join
* in any order, eg C to A and then to B. When C is much smaller
* than A and B this can be a huge win. So we allow C to be
* joined to just A or just B here, and then make_join_rel has
* to handle the case properly.
*
* Note that actually we'll allow unique-ified C to be joined to
* some other relation D here, too. That is legal, if usually not
* very sane, and this routine is only concerned with legality not
* with whether the join is good strategy.
* ----------
*/
if (match_sjinfo != NULL)
return false;
match_sjinfo = sjinfo;
unique_exchange = true;
reversed = false;
} else if (sjinfo->jointype == JOIN_SEMI && bms_equal(sjinfo->syn_righthand, rel1->relids) &&
((Path*)linitial(rel1->cheapest_total_path))->param_info == NULL &&
create_unique_path(root, rel1, (Path*)linitial(rel1->cheapest_total_path), sjinfo) != NULL) {
if (match_sjinfo != NULL)
return false;
match_sjinfo = sjinfo;
unique_exchange = true;
reversed = true;
} else {
* Otherwise, the proposed join overlaps the RHS but isn't a valid
* implementation of this SJ. But don't panic quite yet: the RHS
* violation might have occurred previously, in one or both input
* relations, in which case we must have previously decided that
* it was OK to commute some other SJ with this one. If we need
* to perform this join to finish building up the RHS, rejecting
* it could lead to not finding any plan at all. (This can occur
* because of the heuristics elsewhere in this file that postpone
* clauseless joins: we might not consider doing a clauseless join
* within the RHS until after we've performed other, validly
* commutable SJs with one or both sides of the clauseless join.)
* This consideration boils down to the rule that if both inputs
* overlap the RHS, we can allow the join --- they are either
* fully within the RHS, or represent previously-allowed joins to
* rels outside it.
*/
if (bms_overlap(rel1->relids, sjinfo->min_righthand) && bms_overlap(rel2->relids, sjinfo->min_righthand))
continue;
* The proposed join could still be legal, but only if we're
* allowed to associate it into the RHS of this SJ. That means
* this SJ must be a LEFT join (not SEMI or ANTI, and certainly
* not FULL) and the proposed join must not overlap the LHS.
*/
if ((sjinfo->jointype != JOIN_LEFT && sjinfo->jointype != JOIN_LEFT_ANTI_FULL) ||
bms_overlap(joinrelids, sjinfo->min_lefthand))
return false;
* To be valid, the proposed join must be a LEFT join; otherwise
* it can't associate into this SJ's RHS. But we may not yet have
* found the SpecialJoinInfo matching the proposed join, so we
* can't test that yet. Remember the requirement for later.
*/
must_be_leftjoin = true;
}
}
* Fail if violated any SJ's RHS and didn't match to a LEFT SJ: the
* proposed join can't associate into an SJ's RHS.
*
* Also, fail if the proposed join's predicate isn't strict; we're
* essentially checking to see if we can apply outer-join identity 3, and
* that's a requirement. (This check may be redundant with checks in
* make_outerjoininfo, but I'm not quite sure, and it's cheap to test.)
*/
if (must_be_leftjoin &&
(match_sjinfo == NULL ||
(match_sjinfo->jointype != JOIN_LEFT && match_sjinfo->jointype != JOIN_LEFT_ANTI_FULL) ||
!match_sjinfo->lhs_strict))
return false;
* We also have to check for constraints imposed by LATERAL references.
* The proposed rels could each contain lateral references to the other,
* in which case the join is impossible. If there are lateral references
* in just one direction, then the join has to be done with a nestloop
* with the lateral referencer on the inside. If the join matches an SJ
* that cannot be implemented by such a nestloop, the join is impossible.
*/
lateral_fwd = lateral_rev = false;
foreach(l, root->lateral_info_list)
{
LateralJoinInfo *ljinfo = (LateralJoinInfo *) lfirst(l);
if (bms_is_subset(ljinfo->lateral_rhs, rel2->relids) &&
bms_overlap(ljinfo->lateral_lhs, rel1->relids))
{
if (lateral_rev)
return false;
lateral_fwd = true;
if (!bms_is_subset(ljinfo->lateral_lhs, rel1->relids))
return false;
if (match_sjinfo &&
((reversed && !unique_exchange) || match_sjinfo->jointype == JOIN_FULL))
return false;
}
if (bms_is_subset(ljinfo->lateral_rhs, rel1->relids) &&
bms_overlap(ljinfo->lateral_lhs, rel2->relids))
{
if (lateral_fwd)
return false;
lateral_rev = true;
if (!bms_is_subset(ljinfo->lateral_lhs, rel2->relids))
return false;
if (match_sjinfo &&
((!reversed && !unique_exchange) || match_sjinfo->jointype == JOIN_FULL))
return false;
}
}
*sjinfo_p = match_sjinfo;
*reversed_p = reversed;
*straight_join_p = straight_join;
return true;
}
static inline bool IsAsofRelOptInfo(RelOptInfo* rel)
{
ListCell *cell = NULL;
foreach (cell, rel->joininfo) {
RestrictInfo* ri = (RestrictInfo*)lfirst(cell);
if (ri->is_asof) {
return true;
}
}
return false;
}
* IsAsofJoin
* check is it asof join
*/
bool IsAsofJoin(RelOptInfo* rel1, RelOptInfo* rel2)
{
return IsAsofRelOptInfo(rel1) && IsAsofRelOptInfo(rel2);
}
* make_join_rel
* Find or create a join RelOptInfo that represents the join of
* the two given rels, and add to it path information for paths
* created with the two rels as outer and inner rel.
* (The join rel may already contain paths generated from other
* pairs of rels that add up to the same set of base rels.)
*
* NB: will return NULL if attempted join is not valid. This can happen
* when working with outer joins, or with IN or EXISTS clauses that have been
* turned into joins.
*/
RelOptInfo* make_join_rel(PlannerInfo* root, RelOptInfo* rel1, RelOptInfo* rel2)
{
Relids joinrelids;
SpecialJoinInfo* sjinfo = NULL;
bool reversed = false;
bool straight_join = false;
SpecialJoinInfo sjinfo_data;
RelOptInfo* joinrel = NULL;
List* restrictlist = NIL;
AssertEreport(!bms_overlap(rel1->relids, rel2->relids), MOD_OPT_JOIN, "rel sets are overlapped");
joinrelids = bms_union(rel1->relids, rel2->relids);
if (!join_is_legal(root, rel1, rel2, joinrelids, &sjinfo, &reversed, &straight_join)) {
bms_free_ext(joinrelids);
return NULL;
}
if (reversed) {
RelOptInfo* trel = rel1;
rel1 = rel2;
rel2 = trel;
}
* If it's a plain inner join, then we won't have found anything in
* join_info_list. Make up a SpecialJoinInfo so that selectivity
* estimation functions will know what's being joined.
*/
if (sjinfo == NULL) {
sjinfo = &sjinfo_data;
sjinfo->type = T_SpecialJoinInfo;
sjinfo->min_lefthand = rel1->relids;
sjinfo->min_righthand = rel2->relids;
sjinfo->syn_lefthand = rel1->relids;
sjinfo->syn_righthand = rel2->relids;
sjinfo->jointype = JOIN_INNER;
sjinfo->lhs_strict = false;
sjinfo->is_straight_join = straight_join;
sjinfo->delay_upper_joins = false;
sjinfo->join_quals = NIL;
}
sjinfo->varratio_cached = true;
* Find or build the join RelOptInfo, and compute the restrictlist that
* goes with this particular joining.
*/
joinrel = build_join_rel(root, joinrelids, rel1, rel2, sjinfo, &restrictlist);
* If we've already proven this join is empty, we needn't consider any
* more paths for it.
*/
if (is_dummy_rel(joinrel)) {
bms_free_ext(joinrelids);
return joinrel;
}
int work_mem_orig = u_sess->opt_cxt.op_work_mem;
int esti_op_mem_orig = root->glob->estiopmem;
if (root->glob->minopmem > 0 && bms_num_members(root->all_baserels) != bms_num_members(joinrel->relids)) {
root->glob->estiopmem =
(int)(root->glob->estiopmem /
ceil(LOG2((double)bms_num_members(root->all_baserels) / bms_num_members(joinrel->relids))));
root->glob->estiopmem = Max(root->glob->minopmem, root->glob->estiopmem);
u_sess->opt_cxt.op_work_mem = Min(root->glob->estiopmem, OPT_MAX_OP_MEM);
AssertEreport(u_sess->opt_cxt.op_work_mem > 0, MOD_OPT_JOIN, "work memory is 0");
}
* Consider paths using each rel as both outer and inner. Depending on
* the join type, a provably empty outer or inner rel might mean the join
* is provably empty too; in which case throw away any previously computed
* paths and mark the join as dummy. (We do it this way since it's
* conceivable that dummy-ness of a multi-element join might only be
* noticeable for certain construction paths.)
*
* Also, a provably constant-false join restriction typically means that
* we can skip evaluating one or both sides of the join. We do this by
* marking the appropriate rel as dummy. For outer joins, a
* constant-false restriction that is pushed down still means the whole
* join is dummy, while a non-pushed-down one means that no inner rows
* will join so we can treat the inner rel as dummy.
*
* We need only consider the jointypes that appear in join_info_list, plus
* JOIN_INNER.
*/
switch (sjinfo->jointype) {
case JOIN_INNER:
if (is_dummy_rel(rel1) || is_dummy_rel(rel2) || restriction_is_constant_false(restrictlist, false)) {
mark_dummy_rel(joinrel);
break;
}
add_paths_to_joinrel(root, joinrel, rel1, rel2, JOIN_INNER, sjinfo, restrictlist);
if (u_sess->attr.attr_sql.dolphin && sjinfo->is_straight_join) {
break;
}
if (!IsAsofJoin(rel1, rel2)) {
add_paths_to_joinrel(root, joinrel, rel2, rel1, JOIN_INNER, sjinfo, restrictlist);
}
break;
case JOIN_LEFT:
case JOIN_LEFT_ANTI_FULL:
if (is_dummy_rel(rel1) || restriction_is_constant_false(restrictlist, true)) {
mark_dummy_rel(joinrel);
break;
}
if (restriction_is_constant_false(restrictlist, false) &&
bms_is_subset(rel2->relids, sjinfo->syn_righthand))
mark_dummy_rel(rel2);
add_paths_to_joinrel(root, joinrel, rel1, rel2, sjinfo->jointype, sjinfo, restrictlist);
add_paths_to_joinrel(root,
joinrel,
rel2,
rel1,
(sjinfo->jointype == JOIN_LEFT) ? JOIN_RIGHT : JOIN_RIGHT_ANTI_FULL,
sjinfo,
restrictlist);
break;
case JOIN_FULL:
if ((is_dummy_rel(rel1) && is_dummy_rel(rel2)) || restriction_is_constant_false(restrictlist, true)) {
mark_dummy_rel(joinrel);
break;
}
add_paths_to_joinrel(root, joinrel, rel1, rel2, sjinfo->jointype, sjinfo, restrictlist);
add_paths_to_joinrel(root, joinrel, rel2, rel1, sjinfo->jointype, sjinfo, restrictlist);
* If there are join quals that aren't mergeable or hashable, we
* may not be able to build any valid plan. Complain here so that
* we can give a somewhat-useful error message. (Since we have no
* flexibility of planning for a full join, there's no chance of
* succeeding later with another pair of input rels.)
*/
if (joinrel->pathlist == NIL && !IS_STREAM)
ereport(ERROR,
(errmodule(MOD_OPT),
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg(
"FULL JOIN is only supported with merge-joinable or hash-joinable join conditions"))));
break;
case JOIN_SEMI:
* We might have a normal semijoin, or a case where we don't have
* enough rels to do the semijoin but can unique-ify the RHS and
* then do an innerjoin (see comments in join_is_legal). In the
* latter case we can't apply JOIN_SEMI joining.
*/
if (bms_is_subset(sjinfo->min_lefthand, rel1->relids) &&
bms_is_subset(sjinfo->min_righthand, rel2->relids)) {
if (is_dummy_rel(rel1) || is_dummy_rel(rel2) || restriction_is_constant_false(restrictlist, false)) {
mark_dummy_rel(joinrel);
break;
}
add_paths_to_joinrel(root, joinrel, rel1, rel2, JOIN_SEMI, sjinfo, restrictlist);
add_paths_to_joinrel(root, joinrel, rel2, rel1, JOIN_RIGHT_SEMI, sjinfo, restrictlist);
}
* If we know how to unique-ify the RHS and one input rel is
* exactly the RHS (not a superset) we can consider unique-ifying
* it and then doing a regular join. (The create_unique_path
* check here is probably redundant with what join_is_legal did,
* but if so the check is cheap because it's cached. So test
* anyway to be sure.)
*/
if (bms_equal(sjinfo->syn_righthand, rel2->relids) &&
create_unique_path(root, rel2, (Path*)linitial(rel2->cheapest_total_path), sjinfo) != NULL) {
if (is_dummy_rel(rel1) || is_dummy_rel(rel2) || restriction_is_constant_false(restrictlist, false)) {
mark_dummy_rel(joinrel);
break;
}
add_paths_to_joinrel(root, joinrel, rel1, rel2, JOIN_UNIQUE_INNER, sjinfo, restrictlist);
add_paths_to_joinrel(root, joinrel, rel2, rel1, JOIN_UNIQUE_OUTER, sjinfo, restrictlist);
}
break;
case JOIN_ANTI:
if (is_dummy_rel(rel1) || restriction_is_constant_false(restrictlist, true)) {
mark_dummy_rel(joinrel);
break;
}
if (restriction_is_constant_false(restrictlist, false) &&
bms_is_subset(rel2->relids, sjinfo->syn_righthand))
mark_dummy_rel(rel2);
add_paths_to_joinrel(root, joinrel, rel1, rel2, JOIN_ANTI, sjinfo, restrictlist);
add_paths_to_joinrel(root, joinrel, rel2, rel1, JOIN_RIGHT_ANTI, sjinfo, restrictlist);
break;
default: {
ereport(ERROR,
(errmodule(MOD_OPT),
errcode(ERRCODE_UNRECOGNIZED_NODE_TYPE),
errmsg("unrecognized join type when make a join rel: %d", (int)sjinfo->jointype)));
} break;
}
bms_free_ext(joinrelids);
u_sess->opt_cxt.op_work_mem = work_mem_orig;
root->glob->estiopmem = esti_op_mem_orig;
#ifdef STREAMPLAN
* If there are join quals that cannot generate Stream plan, we mark it and try
* to get a PGXC plan instead.
* e.g. cannot broadcast hashed results for inner plan of semi join when outer
* plan is replicated now.
*/
if (IS_STREAM && NIL == joinrel->pathlist) {
* We remove the useless RelOptInfo and then try other join path if the current level
* is not the top level.
*/
if (ENABLE_PRED_PUSH_ALL(root) && root->join_rel_level &&
root->join_cur_level < list_length(root->join_rel_level[1])) {
remove_join_rel(root, joinrel);
return NULL;
} else {
errno_t sprintf_rc = sprintf_s(u_sess->opt_cxt.not_shipping_info->not_shipping_reason,
NOTPLANSHIPPING_LENGTH,
"\"Full Join\" on redistribution unsupported data type");
securec_check_ss_c(sprintf_rc, "\0", "\0");
mark_stream_unsupport();
mark_dummy_rel(joinrel);
}
}
#endif
return joinrel;
}
* have_join_order_restriction
* Detect whether the two relations should be joined to satisfy
* a join-order restriction arising from special joins.
*
* In practice this is always used with have_relevant_joinclause(), and so
* could be merged with that function, but it seems clearer to separate the
* two concerns. We need this test because there are degenerate cases where
* a clauseless join must be performed to satisfy join-order restrictions.
*
* Note: this is only a problem if one side of a degenerate outer join
* contains multiple rels, or a clauseless join is required within an
* IN/EXISTS RHS; else we will find a join path via the "last ditch" case in
* join_search_one_level(). We could dispense with this test if we were
* willing to try bushy plans in the "last ditch" case, but that seems much
* less efficient.
*/
bool have_join_order_restriction(PlannerInfo* root, RelOptInfo* rel1, RelOptInfo* rel2)
{
bool result = false;
ListCell* l = NULL;
* If either side has a lateral reference to the other, attempt the join
* regardless of outer-join considerations.
*/
foreach(l, root->lateral_info_list)
{
LateralJoinInfo *ljinfo = (LateralJoinInfo *) lfirst(l);
if (bms_is_subset(ljinfo->lateral_rhs, rel2->relids) &&
bms_overlap(ljinfo->lateral_lhs, rel1->relids))
return true;
if (bms_is_subset(ljinfo->lateral_rhs, rel1->relids) &&
bms_overlap(ljinfo->lateral_lhs, rel2->relids))
return true;
}
* It's possible that the rels correspond to the left and right sides of a
* degenerate outer join, that is, one with no joinclause mentioning the
* non-nullable side; in which case we should force the join to occur.
*
* Also, the two rels could represent a clauseless join that has to be
* completed to build up the LHS or RHS of an outer join.
*/
foreach (l, root->join_info_list) {
SpecialJoinInfo* sjinfo = (SpecialJoinInfo*)lfirst(l);
if (sjinfo->jointype == JOIN_FULL)
continue;
if (bms_is_subset(sjinfo->min_lefthand, rel1->relids) && bms_is_subset(sjinfo->min_righthand, rel2->relids)) {
result = true;
break;
}
if (bms_is_subset(sjinfo->min_lefthand, rel2->relids) && bms_is_subset(sjinfo->min_righthand, rel1->relids)) {
result = true;
break;
}
* Might we need to join these rels to complete the RHS? We have to
* use "overlap" tests since either rel might include a lower SJ that
* has been proven to commute with this one.
*/
if (bms_overlap(sjinfo->min_righthand, rel1->relids) && bms_overlap(sjinfo->min_righthand, rel2->relids)) {
result = true;
break;
}
if (bms_overlap(sjinfo->min_lefthand, rel1->relids) && bms_overlap(sjinfo->min_lefthand, rel2->relids)) {
result = true;
break;
}
}
* We do not force the join to occur if either input rel can legally be
* joined to anything else using joinclauses. This essentially means that
* clauseless bushy joins are put off as long as possible. The reason is
* that when there is a join order restriction high up in the join tree
* (that is, with many rels inside the LHS or RHS), we would otherwise
* expend lots of effort considering very stupid join combinations within
* its LHS or RHS.
*/
if (result) {
if (has_legal_joinclause(root, rel1) || has_legal_joinclause(root, rel2))
result = false;
}
return result;
}
* has_join_restriction
* Detect whether the specified relation has join-order restrictions
* due to being inside an outer join or an IN (sub-SELECT).
*
* Essentially, this tests whether have_join_order_restriction() could
* succeed with this rel and some other one. It's OK if we sometimes
* say "true" incorrectly. (Therefore, we don't bother with the relatively
* expensive has_legal_joinclause test.)
*/
static bool has_join_restriction(PlannerInfo* root, RelOptInfo* rel)
{
ListCell* l = NULL;
foreach(l, root->lateral_info_list)
{
LateralJoinInfo *ljinfo = (LateralJoinInfo *) lfirst(l);
if (bms_is_subset(ljinfo->lateral_rhs, rel->relids) ||
bms_overlap(ljinfo->lateral_lhs, rel->relids))
return true;
}
foreach (l, root->join_info_list) {
SpecialJoinInfo* sjinfo = (SpecialJoinInfo*)lfirst(l);
if (sjinfo->jointype == JOIN_FULL)
continue;
if (bms_is_subset(sjinfo->min_lefthand, rel->relids) && bms_is_subset(sjinfo->min_righthand, rel->relids))
continue;
if (bms_overlap(sjinfo->min_lefthand, rel->relids) || bms_overlap(sjinfo->min_righthand, rel->relids))
return true;
}
return false;
}
* has_legal_joinclause
* Detect whether the specified relation can legally be joined
* to any other rels using join clauses.
*
* We consider only joins to single other relations in the current
* initial_rels list. This is sufficient to get a "true" result in most real
* queries, and an occasional erroneous "false" will only cost a bit more
* planning time. The reason for this limitation is that considering joins to
* other joins would require proving that the other join rel can legally be
* formed, which seems like too much trouble for something that's only a
* heuristic to save planning time. (Note: we must look at initial_rels
* and not all of the query, since when we are planning a sub-joinlist we
* may be forced to make clauseless joins within initial_rels even though
* there are join clauses linking to other parts of the query.)
*/
static bool has_legal_joinclause(PlannerInfo* root, RelOptInfo* rel)
{
ListCell* lc = NULL;
foreach (lc, root->initial_rels) {
RelOptInfo* rel2 = (RelOptInfo*)lfirst(lc);
if (bms_overlap(rel->relids, rel2->relids))
continue;
if (have_relevant_joinclause(root, rel, rel2)) {
Relids joinrelids;
SpecialJoinInfo* sjinfo = NULL;
bool reversed = false;
bool straight_join = false;
joinrelids = bms_union(rel->relids, rel2->relids);
if (join_is_legal(root, rel, rel2, joinrelids, &sjinfo, &reversed, &straight_join)) {
bms_free_ext(joinrelids);
return true;
}
bms_free_ext(joinrelids);
}
}
return false;
}
* is_dummy_rel --- has relation been proven empty?
*/
static bool is_dummy_rel(const RelOptInfo* rel)
{
return IS_DUMMY_REL(rel);
}
* Mark a relation as proven empty.
*
* During GEQO planning, this can get invoked more than once on the same
* baserel struct, so it's worth checking to see if the rel is already marked
* dummy.
*
* Also, when called during GEQO join planning, we are in a short-lived
* memory context. We must make sure that the dummy path attached to a
* baserel survives the GEQO cycle, else the baserel is trashed for future
* GEQO cycles. On the other hand, when we are marking a joinrel during GEQO,
* we don't want the dummy path to clutter the main planning context. Upshot
* is that the best solution is to explicitly make the dummy path in the same
* context the given RelOptInfo is in.
*/
static void mark_dummy_rel(RelOptInfo* rel)
{
MemoryContext oldcontext;
if (is_dummy_rel(rel))
return;
oldcontext = MemoryContextSwitchTo(GetMemoryChunkContext(rel));
rel->rows = 0;
rel->pathlist = NIL;
Path* append_path = (Path*)create_append_path(NULL, rel, NIL, NULL);
if (append_path != NULL) {
add_path(NULL, rel, append_path);
}
set_cheapest(rel);
(void)MemoryContextSwitchTo(oldcontext);
}
* restriction_is_constant_false --- is a restrictlist just FALSE?
*
* In cases where a qual is provably constant FALSE, eval_const_expressions
* will generally have thrown away anything that's ANDed with it. In outer
* join situations this will leave us computing cartesian products only to
* decide there's no match for an outer row, which is pretty stupid. So,
* we need to detect the case.
*
* If only_pushed_down is TRUE, then consider only pushed-down quals.
*/
static bool restriction_is_constant_false(List* restrictlist, bool only_pushed_down)
{
ListCell* lc = NULL;
* Despite the above comment, the restriction list we see here might
* possibly have other members besides the FALSE constant, since other
* quals could get "pushed down" to the outer join level. So we check
* each member of the list.
*/
foreach (lc, restrictlist) {
RestrictInfo* rinfo = (RestrictInfo*)lfirst(lc);
AssertEreport(IsA(rinfo, RestrictInfo), MOD_OPT_JOIN, "Restriction information is incorrect");
if (only_pushed_down && !rinfo->is_pushed_down)
continue;
if (rinfo->clause && IsA(rinfo->clause, Const)) {
Const* con = (Const*)rinfo->clause;
if (con->constisnull)
return true;
if (!DatumGetBool(con->constvalue))
return true;
}
}
return false;
}