Header And Logo
|
#include "postgres.h"#include "optimizer/joininfo.h"#include "optimizer/pathnode.h"#include "optimizer/paths.h"#include "utils/memutils.h"
Go to the source code of this file.
Functions | |
| 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 (RelOptInfo *rel) |
| static void | mark_dummy_rel (RelOptInfo *rel) |
| static bool | restriction_is_constant_false (List *restrictlist, bool only_pushed_down) |
| void | join_search_one_level (PlannerInfo *root, int level) |
| static bool | join_is_legal (PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2, Relids joinrelids, SpecialJoinInfo **sjinfo_p, bool *reversed_p) |
| RelOptInfo * | make_join_rel (PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2) |
| bool | have_join_order_restriction (PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2) |
| static bool has_join_restriction | ( | PlannerInfo * | root, | |
| RelOptInfo * | rel | |||
| ) | [static] |
Definition at line 923 of file joinrels.c.
References bms_is_member(), bms_is_subset(), bms_overlap(), JOIN_FULL, PlannerInfo::join_info_list, SpecialJoinInfo::jointype, PlannerInfo::lateral_info_list, LateralJoinInfo::lateral_lhs, LateralJoinInfo::lateral_rhs, lfirst, SpecialJoinInfo::min_lefthand, SpecialJoinInfo::min_righthand, and RelOptInfo::relids.
Referenced by join_search_one_level().
{
ListCell *l;
foreach(l, root->lateral_info_list)
{
LateralJoinInfo *ljinfo = (LateralJoinInfo *) lfirst(l);
if (bms_is_member(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);
/* ignore full joins --- other mechanisms preserve their ordering */
if (sjinfo->jointype == JOIN_FULL)
continue;
/* ignore if SJ is already contained in rel */
if (bms_is_subset(sjinfo->min_lefthand, rel->relids) &&
bms_is_subset(sjinfo->min_righthand, rel->relids))
continue;
/* restricted if it overlaps LHS or RHS, but doesn't contain SJ */
if (bms_overlap(sjinfo->min_lefthand, rel->relids) ||
bms_overlap(sjinfo->min_righthand, rel->relids))
return true;
}
return false;
}
| static bool has_legal_joinclause | ( | PlannerInfo * | root, | |
| RelOptInfo * | rel | |||
| ) | [static] |
Definition at line 976 of file joinrels.c.
References bms_free(), bms_overlap(), bms_union(), have_relevant_joinclause(), PlannerInfo::initial_rels, join_is_legal(), lfirst, and RelOptInfo::relids.
Referenced by have_join_order_restriction().
{
ListCell *lc;
foreach(lc, root->initial_rels)
{
RelOptInfo *rel2 = (RelOptInfo *) lfirst(lc);
/* ignore rels that are already in "rel" */
if (bms_overlap(rel->relids, rel2->relids))
continue;
if (have_relevant_joinclause(root, rel, rel2))
{
Relids joinrelids;
SpecialJoinInfo *sjinfo;
bool reversed;
/* join_is_legal needs relids of the union */
joinrelids = bms_union(rel->relids, rel2->relids);
if (join_is_legal(root, rel, rel2, joinrelids,
&sjinfo, &reversed))
{
/* Yes, this will work */
bms_free(joinrelids);
return true;
}
bms_free(joinrelids);
}
}
return false;
}
| bool have_join_order_restriction | ( | PlannerInfo * | root, | |
| RelOptInfo * | rel1, | |||
| RelOptInfo * | rel2 | |||
| ) |
Definition at line 818 of file joinrels.c.
References bms_is_member(), bms_is_subset(), bms_overlap(), has_legal_joinclause(), JOIN_FULL, PlannerInfo::join_info_list, SpecialJoinInfo::jointype, PlannerInfo::lateral_info_list, LateralJoinInfo::lateral_lhs, LateralJoinInfo::lateral_rhs, lfirst, SpecialJoinInfo::min_lefthand, SpecialJoinInfo::min_righthand, and RelOptInfo::relids.
Referenced by desirable_join(), join_search_one_level(), and make_rels_by_clause_joins().
{
bool result = false;
ListCell *l;
/*
* 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_member(ljinfo->lateral_rhs, rel2->relids) &&
bms_overlap(ljinfo->lateral_lhs, rel1->relids))
return true;
if (bms_is_member(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);
/* ignore full joins --- other mechanisms handle them */
if (sjinfo->jointype == JOIN_FULL)
continue;
/* Can we perform the SJ with these rels? */
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;
}
/* Likewise for the LHS. */
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;
}
| static bool is_dummy_rel | ( | RelOptInfo * | rel | ) | [static] |
Definition at line 1017 of file joinrels.c.
References IS_DUMMY_REL.
Referenced by make_join_rel(), and mark_dummy_rel().
{
return IS_DUMMY_REL(rel);
}
| static bool join_is_legal | ( | PlannerInfo * | root, | |
| RelOptInfo * | rel1, | |||
| RelOptInfo * | rel2, | |||
| Relids | joinrelids, | |||
| SpecialJoinInfo ** | sjinfo_p, | |||
| bool * | reversed_p | |||
| ) | [static] |
Definition at line 327 of file joinrels.c.
References Assert, bms_equal(), bms_is_member(), bms_is_subset(), bms_overlap(), RelOptInfo::cheapest_total_path, create_unique_path(), JOIN_FULL, PlannerInfo::join_info_list, JOIN_SEMI, SpecialJoinInfo::jointype, PlannerInfo::lateral_info_list, LateralJoinInfo::lateral_lhs, LateralJoinInfo::lateral_rhs, lfirst, SpecialJoinInfo::min_lefthand, SpecialJoinInfo::min_righthand, NULL, RelOptInfo::relids, and SpecialJoinInfo::syn_righthand.
Referenced by has_legal_joinclause(), and make_join_rel().
{
SpecialJoinInfo *match_sjinfo;
bool reversed;
bool unique_ified;
bool is_valid_inner;
bool lateral_fwd;
bool lateral_rev;
ListCell *l;
/*
* 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;
/*
* 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 conflicts.
*/
match_sjinfo = NULL;
reversed = false;
unique_ified = false;
is_valid_inner = true;
foreach(l, root->join_info_list)
{
SpecialJoinInfo *sjinfo = (SpecialJoinInfo *) lfirst(l);
/*
* 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.
*
* Barf if we get matches to more than one SJ (is that possible?)
*/
if (bms_is_subset(sjinfo->min_lefthand, rel1->relids) &&
bms_is_subset(sjinfo->min_righthand, rel2->relids))
{
if (match_sjinfo)
return false; /* invalid join path */
match_sjinfo = sjinfo;
reversed = false;
}
else if (bms_is_subset(sjinfo->min_lefthand, rel2->relids) &&
bms_is_subset(sjinfo->min_righthand, rel1->relids))
{
if (match_sjinfo)
return false; /* invalid join path */
match_sjinfo = sjinfo;
reversed = true;
}
else if (sjinfo->jointype == JOIN_SEMI &&
bms_equal(sjinfo->syn_righthand, rel2->relids) &&
create_unique_path(root, rel2, 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)
return false; /* invalid join path */
match_sjinfo = sjinfo;
reversed = false;
unique_ified = true;
}
else if (sjinfo->jointype == JOIN_SEMI &&
bms_equal(sjinfo->syn_righthand, rel1->relids) &&
create_unique_path(root, rel1, rel1->cheapest_total_path,
sjinfo) != NULL)
{
/* Reversed semijoin case */
if (match_sjinfo)
return false; /* invalid join path */
match_sjinfo = sjinfo;
reversed = true;
unique_ified = true;
}
else
{
/*----------
* Otherwise, the proposed join overlaps the RHS but isn't
* a valid implementation of this SJ. It might still be
* a legal join, however. If both inputs overlap the RHS,
* assume that it's OK. Since the inputs presumably got past
* this function's checks previously, they can't overlap the
* LHS and their violations of the RHS boundary must represent
* SJs that have been determined to commute with this one.
* We have to allow this to work correctly in cases like
* (a LEFT JOIN (b JOIN (c LEFT JOIN d)))
* when the c/d join has been determined to commute with the join
* to a, and hence d is not part of min_righthand for the upper
* join. It should be legal to join b to c/d but this will appear
* as a violation of the upper join's RHS.
* Furthermore, if one input overlaps the RHS and the other does
* not, we should still allow the join if it is a valid
* implementation of some other SJ. We have to allow this to
* support the associative identity
* (a LJ b on Pab) LJ c ON Pbc = a LJ (b LJ c ON Pbc) on Pab
* since joining B directly to C violates the lower SJ's RHS.
* We assume that make_outerjoininfo() set things up correctly
* so that we'll only match to some SJ if the join is valid.
* Set flag here to check at bottom of loop.
*----------
*/
if (sjinfo->jointype != JOIN_SEMI &&
bms_overlap(rel1->relids, sjinfo->min_righthand) &&
bms_overlap(rel2->relids, sjinfo->min_righthand))
{
/* seems OK */
Assert(!bms_overlap(joinrelids, sjinfo->min_lefthand));
}
else
is_valid_inner = false;
}
}
/*
* Fail if violated some SJ's RHS and didn't match to another SJ. However,
* "matching" to a semijoin we are implementing by unique-ification
* doesn't count (think: it's really an inner join).
*/
if (!is_valid_inner &&
(match_sjinfo == NULL || unique_ified))
return false; /* invalid join path */
/*
* 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_member(ljinfo->lateral_rhs, rel2->relids) &&
bms_overlap(ljinfo->lateral_lhs, rel1->relids))
{
/* has to be implemented as nestloop with rel1 on left */
if (lateral_rev)
return false; /* have lateral refs in both directions */
lateral_fwd = true;
if (!bms_is_subset(ljinfo->lateral_lhs, rel1->relids))
return false; /* rel1 can't compute the required parameter */
if (match_sjinfo &&
(reversed || match_sjinfo->jointype == JOIN_FULL))
return false; /* not implementable as nestloop */
}
if (bms_is_member(ljinfo->lateral_rhs, rel1->relids) &&
bms_overlap(ljinfo->lateral_lhs, rel2->relids))
{
/* has to be implemented as nestloop with rel2 on left */
if (lateral_fwd)
return false; /* have lateral refs in both directions */
lateral_rev = true;
if (!bms_is_subset(ljinfo->lateral_lhs, rel2->relids))
return false; /* rel2 can't compute the required parameter */
if (match_sjinfo &&
(!reversed || match_sjinfo->jointype == JOIN_FULL))
return false; /* not implementable as nestloop */
}
}
/* Otherwise, it's a valid join */
*sjinfo_p = match_sjinfo;
*reversed_p = reversed;
return true;
}
| void join_search_one_level | ( | PlannerInfo * | root, | |
| int | level | |||
| ) |
Definition at line 51 of file joinrels.c.
References Assert, bms_overlap(), elog, ERROR, for_each_cell, RelOptInfo::has_eclass_joins, has_join_restriction(), have_join_order_restriction(), have_relevant_joinclause(), PlannerInfo::join_cur_level, PlannerInfo::join_info_list, PlannerInfo::join_rel_level, RelOptInfo::joininfo, PlannerInfo::lateral_info_list, lfirst, list_head(), lnext, make_join_rel(), make_rels_by_clause_joins(), make_rels_by_clauseless_joins(), NIL, and RelOptInfo::relids.
Referenced by standard_join_search().
{
List **joinrels = root->join_rel_level;
ListCell *r;
int k;
Assert(joinrels[level] == NIL);
/* Set join_cur_level so that new joinrels are added to proper list */
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);
if (old_rel->joininfo != NIL || old_rel->has_eclass_joins ||
has_join_restriction(root, old_rel))
{
/*
* 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;
if (level == 2) /* consider remaining initial rels */
other_rels = lnext(r);
else /* consider all initial rels */
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;
ListCell *r2;
/*
* 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); /* only consider remaining rels */
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 and no lateral references
* 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)
elog(ERROR, "failed to build any %d-way joins", level);
}
}
| RelOptInfo* make_join_rel | ( | PlannerInfo * | root, | |
| RelOptInfo * | rel1, | |||
| RelOptInfo * | rel2 | |||
| ) |
Definition at line 577 of file joinrels.c.
References add_paths_to_joinrel(), Assert, bms_equal(), bms_free(), bms_is_subset(), bms_overlap(), bms_union(), build_join_rel(), RelOptInfo::cheapest_total_path, create_unique_path(), SpecialJoinInfo::delay_upper_joins, elog, ereport, errcode(), errmsg(), ERROR, is_dummy_rel(), JOIN_ANTI, JOIN_FULL, JOIN_INNER, join_is_legal(), JOIN_LEFT, SpecialJoinInfo::join_quals, JOIN_RIGHT, JOIN_SEMI, JOIN_UNIQUE_INNER, JOIN_UNIQUE_OUTER, SpecialJoinInfo::jointype, SpecialJoinInfo::lhs_strict, mark_dummy_rel(), SpecialJoinInfo::min_lefthand, SpecialJoinInfo::min_righthand, NIL, NULL, RelOptInfo::pathlist, RelOptInfo::relids, restriction_is_constant_false(), SpecialJoinInfo::syn_lefthand, SpecialJoinInfo::syn_righthand, and SpecialJoinInfo::type.
Referenced by join_search_one_level(), make_rels_by_clause_joins(), make_rels_by_clauseless_joins(), and merge_clump().
{
Relids joinrelids;
SpecialJoinInfo *sjinfo;
bool reversed;
SpecialJoinInfo sjinfo_data;
RelOptInfo *joinrel;
List *restrictlist;
/* We should never try to join two overlapping sets of rels. */
Assert(!bms_overlap(rel1->relids, rel2->relids));
/* Construct Relids set that identifies the joinrel. */
joinrelids = bms_union(rel1->relids, rel2->relids);
/* Check validity and determine join type. */
if (!join_is_legal(root, rel1, rel2, joinrelids,
&sjinfo, &reversed))
{
/* invalid join path */
bms_free(joinrelids);
return NULL;
}
/* Swap rels if needed to match the join info. */
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;
/* we don't bother trying to make the remaining fields valid */
sjinfo->lhs_strict = false;
sjinfo->delay_upper_joins = false;
sjinfo->join_quals = NIL;
}
/*
* 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(joinrelids);
return joinrel;
}
/*
* 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);
add_paths_to_joinrel(root, joinrel, rel2, rel1,
JOIN_INNER, sjinfo,
restrictlist);
break;
case JOIN_LEFT:
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_LEFT, sjinfo,
restrictlist);
add_paths_to_joinrel(root, joinrel, rel2, rel1,
JOIN_RIGHT, 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,
JOIN_FULL, sjinfo,
restrictlist);
add_paths_to_joinrel(root, joinrel, rel2, rel1,
JOIN_FULL, 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)
ereport(ERROR,
(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);
}
/*
* 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, 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);
break;
default:
/* other values not expected here */
elog(ERROR, "unrecognized join type: %d", (int) sjinfo->jointype);
break;
}
bms_free(joinrelids);
return joinrel;
}
| static void make_rels_by_clause_joins | ( | PlannerInfo * | root, | |
| RelOptInfo * | old_rel, | |||
| ListCell * | other_rels | |||
| ) | [static] |
Definition at line 260 of file joinrels.c.
References bms_overlap(), for_each_cell, have_join_order_restriction(), have_relevant_joinclause(), lfirst, make_join_rel(), and RelOptInfo::relids.
Referenced by join_search_one_level().
{
ListCell *l;
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);
}
}
}
| static void make_rels_by_clauseless_joins | ( | PlannerInfo * | root, | |
| RelOptInfo * | old_rel, | |||
| ListCell * | other_rels | |||
| ) | [static] |
Definition at line 294 of file joinrels.c.
References bms_overlap(), for_each_cell, lfirst, make_join_rel(), and RelOptInfo::relids.
Referenced by join_search_one_level().
{
ListCell *l;
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);
}
}
}
| static void mark_dummy_rel | ( | RelOptInfo * | rel | ) | [static] |
Definition at line 1038 of file joinrels.c.
References add_path(), create_append_path(), GetMemoryChunkContext(), is_dummy_rel(), MemoryContextSwitchTo(), NIL, NULL, RelOptInfo::pathlist, RelOptInfo::rows, and set_cheapest().
Referenced by make_join_rel().
{
MemoryContext oldcontext;
/* Already marked? */
if (is_dummy_rel(rel))
return;
/* No, so choose correct context to make the dummy path in */
oldcontext = MemoryContextSwitchTo(GetMemoryChunkContext(rel));
/* Set dummy size estimate */
rel->rows = 0;
/* Evict any previously chosen paths */
rel->pathlist = NIL;
/* Set up the dummy path */
add_path(rel, (Path *) create_append_path(rel, NIL, NULL));
/* Set or update cheapest_total_path and related fields */
set_cheapest(rel);
MemoryContextSwitchTo(oldcontext);
}
Definition at line 1077 of file joinrels.c.
References Assert, RestrictInfo::clause, Const::constisnull, Const::constvalue, DatumGetBool, RestrictInfo::is_pushed_down, IsA, and lfirst.
Referenced by make_join_rel().
{
ListCell *lc;
/*
* 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);
Assert(IsA(rinfo, RestrictInfo));
if (only_pushed_down && !rinfo->is_pushed_down)
continue;
if (rinfo->clause && IsA(rinfo->clause, Const))
{
Const *con = (Const *) rinfo->clause;
/* constant NULL is as good as constant FALSE for our purposes */
if (con->constisnull)
return true;
if (!DatumGetBool(con->constvalue))
return true;
}
}
return false;
}
1.7.1