/*
* add_paths_to_joinrel
* Given a join relation and two component rels from which it can be made,
* consider all possible paths that use the two component rels as outer
* and inner rel respectively. Add these paths to the join rel's pathlist
* if they survive comparison with other paths (and remove any existing
* paths that are dominated by these paths).
*
* Modifies the pathlist field of the joinrel node to contain the best
* paths found so far.
*
* jointype is not necessarily the same as sjinfo->jointype; it might be
* "flipped around" if we are considering joining the rels in the opposite
* direction from what's indicated in sjinfo.
*
* Also, this routine and others in this module accept the special JoinTypes
* JOIN_UNIQUE_OUTER and JOIN_UNIQUE_INNER to indicate that we should
* unique-ify the outer or inner relation and then apply a regular inner
* join. These values are not allowed to propagate outside this module,
* however. Path cost estimation code may need to recognize that it's
* dealing with such a case --- the combination of nominal jointype INNER
* with sjinfo->jointype == JOIN_SEMI indicates that.
*/
void
add_paths_to_joinrel(PlannerInfo *root,
RelOptInfo *joinrel,
RelOptInfo *outerrel,
RelOptInfo *innerrel,
JoinType jointype,
SpecialJoinInfo *sjinfo,
List *restrictlist)
{
List *mergeclause_list = NIL;
/*
* 0. Consider join removal. This is always the most efficient strategy,
* so if it works, there's no need to consider anything further.
*/
if (join_is_removable(root, joinrel, outerrel, innerrel,
restrictlist, jointype))
{
generate_outer_only(root, joinrel, outerrel);
return;
}
/*
* Find potential mergejoin clauses. We can skip this if we are not
* interested in doing a mergejoin. However, mergejoin is currently our
* only way of implementing full outer joins, so override mergejoin
* disable if it's a full join.
*
* Note: do this after join_is_removable(), because this sets the
* outer_is_left flags in the mergejoin clauses, while join_is_removable
* uses those flags for its own purposes. Currently, they set the flags
* the same way anyway, but let's avoid unnecessary entanglement.
*/
if (enable_mergejoin || jointype == JOIN_FULL)
mergeclause_list = select_mergejoin_clauses(root,
joinrel,
outerrel,
innerrel,
restrictlist,
jointype);
/*
* 1. Consider mergejoin paths where both relations must be explicitly
* sorted.
*/
sort_inner_and_outer(root, joinrel, outerrel, innerrel,
restrictlist, mergeclause_list, jointype, sjinfo);
/*
* 2. Consider paths where the outer relation need not be explicitly
* sorted. This includes both nestloops and mergejoins where the outer
* path is already ordered.
*/
match_unsorted_outer(root, joinrel, outerrel, innerrel,
restrictlist, mergeclause_list, jointype, sjinfo);
#ifdef NOT_USED
/*
* 3. Consider paths where the inner relation need not be explicitly
* sorted. This includes mergejoins only (nestloops were already built in
* match_unsorted_outer).
*
* Diked out as redundant 2/13/2000 -- tgl. There isn't any really
* significant difference between the inner and outer side of a mergejoin,
* so match_unsorted_inner creates no paths that aren't equivalent to
* those made by match_unsorted_outer when add_paths_to_joinrel() is
* invoked with the two rels given in the other order.
*/
match_unsorted_inner(root, joinrel, outerrel, innerrel,
restrictlist, mergeclause_list, jointype, sjinfo);
#endif
/*
* 4. Consider paths where both outer and inner relations must be hashed
* before being joined.
*/
if (enable_hashjoin)
hash_inner_and_outer(root, joinrel, outerrel, innerrel,
restrictlist, jointype, sjinfo);
}
/*
* add_paths_to_joinrel
* Given a join relation and two component rels from which it can be made,
* consider all possible paths that use the two component rels as outer
* and inner rel respectively. Add these paths to the join rel's pathlist
* if they survive comparison with other paths (and remove any existing
* paths that are dominated by these paths).
*
* Modifies the pathlist field of the joinrel node to contain the best
* paths found so far.
*/
void
add_paths_to_joinrel(PlannerInfo *root,
RelOptInfo *joinrel,
RelOptInfo *outerrel,
RelOptInfo *innerrel,
JoinType jointype,
List *restrictlist)
{
List *mergeclause_list = NIL;
/*
* Find potential mergejoin clauses. We can skip this if we are not
* interested in doing a mergejoin. However, mergejoin is currently our
* only way of implementing full outer joins, so override mergejoin
* disable if it's a full join.
*/
if (enable_mergejoin || jointype == JOIN_FULL)
mergeclause_list = select_mergejoin_clauses(root,
joinrel,
outerrel,
innerrel,
restrictlist,
jointype);
/*
* 1. Consider mergejoin paths where both relations must be explicitly
* sorted.
*/
sort_inner_and_outer(root, joinrel, outerrel, innerrel,
restrictlist, mergeclause_list, jointype);
/*
* 2. Consider paths where the outer relation need not be explicitly
* sorted. This includes both nestloops and mergejoins where the outer
* path is already ordered.
*/
match_unsorted_outer(root, joinrel, outerrel, innerrel,
restrictlist, mergeclause_list, jointype);
#ifdef NOT_USED
/*
* 3. Consider paths where the inner relation need not be explicitly
* sorted. This includes mergejoins only (nestloops were already built in
* match_unsorted_outer).
*
* Diked out as redundant 2/13/2000 -- tgl. There isn't any really
* significant difference between the inner and outer side of a mergejoin,
* so match_unsorted_inner creates no paths that aren't equivalent to
* those made by match_unsorted_outer when add_paths_to_joinrel() is
* invoked with the two rels given in the other order.
*/
match_unsorted_inner(root, joinrel, outerrel, innerrel,
restrictlist, mergeclause_list, jointype);
#endif
/*
* 4. Consider paths where both outer and inner relations must be hashed
* before being joined.
*/
if (enable_hashjoin)
hash_inner_and_outer(root, joinrel, outerrel, innerrel,
restrictlist, jointype);
}
/*
* add_paths_to_joinrel
* Given a join relation and two component rels from which it can be made,
* consider all possible paths that use the two component rels as outer
* and inner rel respectively. Add these paths to the join rel's pathlist
* if they survive comparison with other paths (and remove any existing
* paths that are dominated by these paths).
*
* Modifies the pathlist field of the joinrel node to contain the best
* paths found so far.
*/
void
add_paths_to_joinrel(PlannerInfo *root,
RelOptInfo *joinrel,
RelOptInfo *outerrel,
RelOptInfo *innerrel,
JoinType jointype,
List *restrictlist)
{
List *mergeclause_list = NIL;
List *hashclause_list;
Assert(outerrel->pathlist &&
outerrel->cheapest_startup_path &&
outerrel->cheapest_total_path);
Assert(innerrel->pathlist &&
innerrel->cheapest_startup_path &&
innerrel->cheapest_total_path);
/*
* Find potential mergejoin clauses. We can skip this if we are not
* interested in doing a mergejoin. However, mergejoin is currently our
* only way of implementing full outer joins, so override mergejoin
* disable if it's a full join.
*
* CDB: Always build mergeclause_list. We need it for motion planning.
*/
mergeclause_list = select_mergejoin_clauses(outerrel,
innerrel,
restrictlist,
jointype);
/*
* 1. Consider mergejoin paths where both relations must be explicitly
* sorted.
*/
if (root->config->enable_mergejoin ||
root->config->mpp_trying_fallback_plan ||
jointype == JOIN_FULL)
sort_inner_and_outer(root, joinrel, outerrel, innerrel,
restrictlist, mergeclause_list, jointype);
/*
* 2. Consider paths where the outer relation need not be explicitly
* sorted. This includes both nestloops and mergejoins where the outer
* path is already ordered.
*/
match_unsorted_outer(root, joinrel, outerrel, innerrel,
restrictlist, mergeclause_list, jointype);
#ifdef NOT_USED
/*
* 3. Consider paths where the inner relation need not be explicitly
* sorted. This includes mergejoins only (nestloops were already built in
* match_unsorted_outer).
*
* Diked out as redundant 2/13/2000 -- tgl. There isn't any really
* significant difference between the inner and outer side of a mergejoin,
* so match_unsorted_inner creates no paths that aren't equivalent to
* those made by match_unsorted_outer when add_paths_to_joinrel() is
* invoked with the two rels given in the other order.
*/
match_unsorted_inner(root, joinrel, outerrel, innerrel,
restrictlist, mergeclause_list, jointype);
#endif
/*
* 4. Consider paths where both outer and inner relations must be hashed
* before being joined.
*
* We consider both the cheapest-total-cost and cheapest-startup-cost
* outer paths. There's no need to consider any but the
* cheapest-total-cost inner path, however.
*/
if (root->config->enable_hashjoin
|| root->config->mpp_trying_fallback_plan)
{
hashclause_list = hashclauses_for_join(restrictlist,
outerrel,
innerrel,
jointype);
if (hashclause_list)
{
hash_inner_and_outer(root,
joinrel,
outerrel->cheapest_total_path,
innerrel->cheapest_total_path,
restrictlist,
mergeclause_list,
hashclause_list,
jointype);
if (outerrel->cheapest_startup_path != outerrel->cheapest_total_path)
hash_inner_and_outer(root,
joinrel,
outerrel->cheapest_startup_path,
innerrel->cheapest_total_path,
restrictlist,
mergeclause_list,
hashclause_list,
jointype);
}
}
}