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Implement SQL-standard WITH clauses, including WITH RECURSIVE.

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There are some unimplemented aspects: recursive queries must use UNION ALL
(should allow UNION too), and we don't have SEARCH or CYCLE clauses.
These might or might not get done for 8.4, but even without them it's a
pretty useful feature.

There are also a couple of small loose ends and definitional quibbles,
which I'll send a memo about to pgsql-hackers shortly.  But let's land
the patch now so we can get on with other development.

Yoshiyuki Asaba, with lots of help from Tatsuo Ishii and Tom Lane
This commit is contained in:
Tom Lane
2008-10-04 21:56:55 +00:00
parent 607b2be7bb
commit 44d5be0e53
77 changed files with 5893 additions and 313 deletions
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120
src/backend/optimizer/path/allpaths.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.173 2008/08/25 22:42:32 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.174 2008/10/04 21:56:53 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -57,6 +57,10 @@ static void set_function_pathlist(PlannerInfo *root, RelOptInfo *rel,
RangeTblEntry *rte);
static void set_values_pathlist(PlannerInfo *root, RelOptInfo *rel,
RangeTblEntry *rte);
static void set_cte_pathlist(PlannerInfo *root, RelOptInfo *rel,
RangeTblEntry *rte);
static void set_worktable_pathlist(PlannerInfo *root, RelOptInfo *rel,
RangeTblEntry *rte);
static RelOptInfo *make_rel_from_joinlist(PlannerInfo *root, List *joinlist);
static bool subquery_is_pushdown_safe(Query *subquery, Query *topquery,
bool *differentTypes);
@ -173,14 +177,22 @@ set_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
}
else if (rel->rtekind == RTE_FUNCTION)
{
/* RangeFunction --- generate a separate plan for it */
/* RangeFunction --- generate a suitable path for it */
set_function_pathlist(root, rel, rte);
}
else if (rel->rtekind == RTE_VALUES)
{
/* Values list --- generate a separate plan for it */
/* Values list --- generate a suitable path for it */
set_values_pathlist(root, rel, rte);
}
else if (rel->rtekind == RTE_CTE)
{
/* CTE reference --- generate a suitable path for it */
if (rte->self_reference)
set_worktable_pathlist(root, rel, rte);
else
set_cte_pathlist(root, rel, rte);
}
else
{
/* Plain relation */
@ -585,8 +597,8 @@ set_subquery_pathlist(PlannerInfo *root, RelOptInfo *rel,
/* Generate the plan for the subquery */
rel->subplan = subquery_planner(root->glob, subquery,
root->query_level + 1,
tuple_fraction,
root,
false, tuple_fraction,
&subroot);
rel->subrtable = subroot->parse->rtable;
@ -640,6 +652,104 @@ set_values_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
set_cheapest(rel);
}
/*
* set_cte_pathlist
* Build the (single) access path for a non-self-reference CTE RTE
*/
static void
set_cte_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
{
Plan *cteplan;
PlannerInfo *cteroot;
Index levelsup;
int ndx;
ListCell *lc;
int plan_id;
/*
* Find the referenced CTE, and locate the plan previously made for it.
*/
levelsup = rte->ctelevelsup;
cteroot = root;
while (levelsup-- > 0)
{
cteroot = cteroot->parent_root;
if (!cteroot) /* shouldn't happen */
elog(ERROR, "bad levelsup for CTE \"%s\"", rte->ctename);
}
/*
* Note: cte_plan_ids can be shorter than cteList, if we are still working
* on planning the CTEs (ie, this is a side-reference from another CTE).
* So we mustn't use forboth here.
*/
ndx = 0;
foreach(lc, cteroot->parse->cteList)
{
CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc);
if (strcmp(cte->ctename, rte->ctename) == 0)
break;
ndx++;
}
if (lc == NULL) /* shouldn't happen */
elog(ERROR, "could not find CTE \"%s\"", rte->ctename);
if (ndx >= list_length(cteroot->cte_plan_ids))
elog(ERROR, "could not find plan for CTE \"%s\"", rte->ctename);
plan_id = list_nth_int(cteroot->cte_plan_ids, ndx);
Assert(plan_id > 0);
cteplan = (Plan *) list_nth(root->glob->subplans, plan_id - 1);
/* Mark rel with estimated output rows, width, etc */
set_cte_size_estimates(root, rel, cteplan);
/* Generate appropriate path */
add_path(rel, create_ctescan_path(root, rel));
/* Select cheapest path (pretty easy in this case...) */
set_cheapest(rel);
}
/*
* set_worktable_pathlist
* Build the (single) access path for a self-reference CTE RTE
*/
static void
set_worktable_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
{
Plan *cteplan;
PlannerInfo *cteroot;
Index levelsup;
/*
* We need to find the non-recursive term's plan, which is in the plan
* level that's processing the recursive UNION, which is one level
* *below* where the CTE comes from.
*/
levelsup = rte->ctelevelsup;
if (levelsup == 0) /* shouldn't happen */
elog(ERROR, "bad levelsup for CTE \"%s\"", rte->ctename);
levelsup--;
cteroot = root;
while (levelsup-- > 0)
{
cteroot = cteroot->parent_root;
if (!cteroot) /* shouldn't happen */
elog(ERROR, "bad levelsup for CTE \"%s\"", rte->ctename);
}
cteplan = cteroot->non_recursive_plan;
if (!cteplan) /* shouldn't happen */
elog(ERROR, "could not find plan for CTE \"%s\"", rte->ctename);
/* Mark rel with estimated output rows, width, etc */
set_cte_size_estimates(root, rel, cteplan);
/* Generate appropriate path */
add_path(rel, create_worktablescan_path(root, rel));
/* Select cheapest path (pretty easy in this case...) */
set_cheapest(rel);
}
/*
* make_rel_from_joinlist
* Build access paths using a "joinlist" to guide the join path search.