On 2016/11/22 18:28, Ashutosh Bapat wrote:
The comments should explain why is the assertion true.
+ /* Shouldn't be NIL */
+ Assert(tlist != NIL);
I noticed that I was wrong; in the Assertion the tlist can be empty. An
example for such a case is:
SELECT 1 FROM (SELECT c1 FROM ft4 WHERE c1 between 50 and 60) t1 FULL
JOIN (SELECT c1 FROM ft5 WHERE c1 between 50 and 60) t2 ON (TRUE);
In this example any columns of the relations ft4 and ft5 wouldn't be
needed for the join or the final output, so both the tlists for the
relations created in deparseRangeTblRef would be empty. Attached is an
updated version fixing this bug. Changes are:
* I removed make_outerrel_subquery/make_innerrel_subquery from fpinfo
and added a new member "is_subquery_rel" to fpinfo, as a flag on whether
to deparse the relation as a subquery.
* I modified deparseRangeTblRef, deparseSelectSql, and is_subquery_var
to see the is_subquery_rel, not
make_outerrel_subquery/make_innerrel_subquery.
* I modified appendSubselectAlias to handle the case where ncols = 0
properly.
* I renamed subquery_rels in fpinfo to lower_subquery_rels, to make it
easy to distinguish this from is_subquery_rel clearly.
* I added regression tests for that.
The rest of the patch is the same as the previous version, but:
+ /* Should be same length */
+ Assert(list_length(tlist) ==
list_length(foreignrel->reltarget->exprs));
I added comments explaining the reason.
The name get_subselect_alias_id() seems to suggest that the function returns
identifier for subselect alias, which isn't correct. It returns the alias
identifiers for deparsing a Var node. But I guess, we have left this to the
committer's judgement.
I agree that the name isn't good, so I changed it to
get_relation_column_alias_ids(). Let me know if it may be better.
I also revised code and comments a bit, just for consistency.
I will update another patch for PHVs on top of the attached one.
Best regards,
Etsuro Fujita
*** a/contrib/postgres_fdw/deparse.c
--- b/contrib/postgres_fdw/deparse.c
***************
*** 109,114 **** typedef struct deparse_expr_cxt
--- 109,116 ----
/* Handy macro to add relation name qualification */
#define ADD_REL_QUALIFIER(buf, varno) \
appendStringInfo((buf), "%s%d.", REL_ALIAS_PREFIX, (varno))
+ #define SS_REL_ALIAS_PREFIX "s"
+ #define SS_COL_ALIAS_PREFIX "c"
/*
* Functions to determine whether an expression can be evaluated safely on
***************
*** 167,172 **** static void appendConditions(List *exprs, deparse_expr_cxt *context);
--- 169,181 ----
static void deparseFromExprForRel(StringInfo buf, PlannerInfo *root,
RelOptInfo *joinrel, bool use_alias, List **params_list);
static void deparseFromExpr(List *quals, deparse_expr_cxt *context);
+ static void deparseRangeTblRef(StringInfo buf, PlannerInfo *root,
+ RelOptInfo *foreignrel, List **params_list);
+ static void appendSubselectAlias(StringInfo buf, int relno, int ncols);
+ static void get_relation_column_alias_ids(Var *node, RelOptInfo *foreignrel,
+ int *relno, int *colno);
+ static bool is_subquery_var(Var *node, RelOptInfo *foreignrel, int *relno,
+ int *colno);
static void deparseAggref(Aggref *node, deparse_expr_cxt *context);
static void appendGroupByClause(List *tlist, deparse_expr_cxt *context);
static void appendAggOrderBy(List *orderList, List *targetList,
***************
*** 990,1001 **** deparseSelectSql(List *tlist, List **retrieved_attrs, deparse_expr_cxt *context)
*/
appendStringInfoString(buf, "SELECT ");
if (foreignrel->reloptkind == RELOPT_JOINREL ||
! foreignrel->reloptkind == RELOPT_UPPER_REL)
! {
! /* For a join relation use the input tlist */
deparseExplicitTargetList(tlist, retrieved_attrs, context);
- }
else
{
/*
--- 999,1013 ----
*/
appendStringInfoString(buf, "SELECT ");
+ /*
+ * For a join relation or an upper relation, use deparseExplicitTargetList.
+ * Likewise, for a relation that is being deparsed as a subquery, use that
+ * function. Otherwise, use deparseTargetList.
+ */
if (foreignrel->reloptkind == RELOPT_JOINREL ||
! foreignrel->reloptkind == RELOPT_UPPER_REL ||
! fpinfo->is_subquery_rel)
deparseExplicitTargetList(tlist, retrieved_attrs, context);
else
{
/*
***************
*** 1155,1165 **** deparseLockingClause(deparse_expr_cxt *context)
--- 1167,1185 ----
StringInfo buf = context->buf;
PlannerInfo *root = context->root;
RelOptInfo *rel = context->scanrel;
+ PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) rel->fdw_private;
int relid = -1;
while ((relid = bms_next_member(rel->relids, relid)) >= 0)
{
/*
+ * Ignore relation if it appears in a lower subquery. Locking clause
+ * for such a relation, if needed, is included in the subquery.
+ */
+ if (bms_is_member(relid, fpinfo->lower_subquery_rels))
+ continue;
+
+ /*
* Add FOR UPDATE/SHARE if appropriate. We apply locking during the
* initial row fetch, rather than later on as is done for local
* tables. The extra roundtrips involved in trying to duplicate the
***************
*** 1347,1364 **** deparseFromExprForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
if (foreignrel->reloptkind == RELOPT_JOINREL)
{
- RelOptInfo *rel_o = fpinfo->outerrel;
- RelOptInfo *rel_i = fpinfo->innerrel;
StringInfoData join_sql_o;
StringInfoData join_sql_i;
/* Deparse outer relation */
initStringInfo(&join_sql_o);
! deparseFromExprForRel(&join_sql_o, root, rel_o, true, params_list);
/* Deparse inner relation */
initStringInfo(&join_sql_i);
! deparseFromExprForRel(&join_sql_i, root, rel_i, true, params_list);
/*
* For a join relation FROM clause entry is deparsed as
--- 1367,1382 ----
if (foreignrel->reloptkind == RELOPT_JOINREL)
{
StringInfoData join_sql_o;
StringInfoData join_sql_i;
/* Deparse outer relation */
initStringInfo(&join_sql_o);
! deparseRangeTblRef(&join_sql_o, root, fpinfo->outerrel, params_list);
/* Deparse inner relation */
initStringInfo(&join_sql_i);
! deparseRangeTblRef(&join_sql_i, root, fpinfo->innerrel, params_list);
/*
* For a join relation FROM clause entry is deparsed as
***************
*** 1414,1419 **** deparseFromExprForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
--- 1432,1601 ----
}
/*
+ * Append FROM clause entry for the given relation to buf.
+ */
+ static void
+ deparseRangeTblRef(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
+ List **params_list)
+ {
+ PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
+
+ Assert(foreignrel->reloptkind == RELOPT_BASEREL ||
+ foreignrel->reloptkind == RELOPT_JOINREL);
+ Assert(fpinfo->local_conds == NIL);
+
+ /* If is_subquery_rel is true, deparse the relation as a subquery. */
+ if (fpinfo->is_subquery_rel)
+ {
+ List *tlist;
+ List *retrieved_attrs;
+
+ /* Build a tlist from the subquery. */
+ tlist = build_tlist_to_deparse(foreignrel);
+
+ /*
+ * Since (1) the expressions in foreignrel's reltarget doesn't contain
+ * any PHVs and (2) foreignrel's local_conds is empty, the tlist
+ * created by build_tlist_to_deparse must be one-to-one with the
+ * expressions.
+ */
+ Assert(list_length(tlist) == list_length(foreignrel->reltarget->exprs));
+
+ /* Append the subquery representing the given relation. */
+ appendStringInfoChar(buf, '(');
+ deparseSelectStmtForRel(buf, root, foreignrel, tlist,
+ fpinfo->remote_conds, NIL,
+ &retrieved_attrs, params_list);
+ appendStringInfoChar(buf, ')');
+
+ /*
+ * Append the subselect alias for references to this relation in the
+ * rest of the query.
+ */
+ appendSubselectAlias(buf, fpinfo->relation_index, list_length(tlist));
+ }
+ else
+ deparseFromExprForRel(buf, root, foreignrel, true, params_list);
+ }
+
+ /*
+ * Append the relation and column aliases to a subquery.
+ *
+ * 'relno' is the relation alias ID.
+ * 'ncols' is the number of the column aliases to add.
+ */
+ static void
+ appendSubselectAlias(StringInfo buf, int relno, int ncols)
+ {
+ int i;
+
+ /* Append the relation alias */
+ appendStringInfo(buf, " %s%d", SS_REL_ALIAS_PREFIX, relno);
+
+ /* Append the column aliases, if needed */
+ if (ncols > 0)
+ {
+ appendStringInfoChar(buf, '(');
+ for (i = 1; i <= ncols; i++)
+ {
+ if (i > 1)
+ appendStringInfoString(buf, ", ");
+
+ appendStringInfo(buf, "%s%d", SS_COL_ALIAS_PREFIX, i);
+ }
+ appendStringInfoChar(buf, ')');
+ }
+ }
+
+ /*
+ * Get the relation and column alias IDs of a given Var node, which belongs
+ * to input foreignrel. They are returned in *relno and *colno respectively.
+ */
+ static void
+ get_relation_column_alias_ids(Var *node, RelOptInfo *foreignrel,
+ int *relno, int *colno)
+ {
+ PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
+ int i;
+ ListCell *lc;
+
+ /* Get the relation alias ID */
+ *relno = fpinfo->relation_index;
+
+ /* Get the column alias ID */
+ i = 1;
+ foreach(lc, foreignrel->reltarget->exprs)
+ {
+ if (equal(lfirst(lc), (Node *) node))
+ {
+ *colno = i;
+ return;
+ }
+ i++;
+ }
+
+ /* Shouldn't get here */
+ elog(ERROR, "unexpected expression in subquery output");
+ }
+
+ /*
+ * Returns true if a given Var node belongs to a relation being deparsed as a
+ * subquery. Returns false otherwise. When returning true, it sets *relno and
+ * *colno to the relation and column alias IDs of the given Var node,
+ * respectively.
+ */
+ static bool
+ is_subquery_var(Var *node, RelOptInfo *foreignrel, int *relno, int *colno)
+ {
+ PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
+ RelOptInfo *outerrel = fpinfo->outerrel;
+ RelOptInfo *innerrel = fpinfo->innerrel;
+
+ if (foreignrel->reloptkind != RELOPT_JOINREL)
+ return false;
+
+ if (!bms_is_member(node->varno, fpinfo->lower_subquery_rels))
+ return false;
+
+ if (bms_is_member(node->varno, outerrel->relids))
+ {
+ PgFdwRelationInfo *fpinfo2 = (PgFdwRelationInfo *) outerrel->fdw_private;
+
+ /*
+ * If outer relation is deparsed as a subquery, get the identifiers for
+ * the relation and column alias to the given Var node.
+ */
+ if (fpinfo2->is_subquery_rel)
+ {
+ get_relation_column_alias_ids(node, outerrel, relno, colno);
+ return true;
+ }
+
+ /* Otherwise, recurse into the outer relation. */
+ return is_subquery_var(node, outerrel, relno, colno);
+ }
+ else
+ {
+ PgFdwRelationInfo *fpinfo2 = (PgFdwRelationInfo *) innerrel->fdw_private;
+
+ Assert(bms_is_member(node->varno, innerrel->relids));
+
+ /*
+ * If inner relation is deparsed as a subquery, get the identifiers for
+ * the relation and column alias to the given Var node.
+ */
+ if (fpinfo2->is_subquery_rel)
+ {
+ get_relation_column_alias_ids(node, innerrel, relno, colno);
+ return true;
+ }
+
+ /* Otherwise, recurse into the inner relation. */
+ return is_subquery_var(node, innerrel, relno, colno);
+ }
+ }
+
+ /*
* deparse remote INSERT statement
*
* The statement text is appended to buf, and we also create an integer List
***************
*** 2057,2066 **** static void
--- 2239,2263 ----
deparseVar(Var *node, deparse_expr_cxt *context)
{
Relids relids = context->scanrel->relids;
+ int relno;
+ int colno;
/* Qualify columns when multiple relations are involved. */
bool qualify_col = (bms_num_members(relids) > 1);
+ /*
+ * If the given Var belongs to a relation deparsed as a subquery, use the
+ * relation and column alias provided by the subquery, instead of the
+ * actual column name.
+ */
+ if (is_subquery_var(node, context->scanrel, &relno, &colno))
+ {
+ appendStringInfo(context->buf, "%s%d.%s%d",
+ SS_REL_ALIAS_PREFIX, relno,
+ SS_COL_ALIAS_PREFIX, colno);
+ return;
+ }
+
if (bms_is_member(node->varno, relids) && node->varlevelsup == 0)
deparseColumnRef(context->buf, node->varno, node->varattno,
context->root, qualify_col);
*** a/contrib/postgres_fdw/expected/postgres_fdw.out
--- b/contrib/postgres_fdw/expected/postgres_fdw.out
***************
*** 1217,1241 **** SELECT t1.c1, t2.c1 FROM ft4 t1 FULL JOIN ft5 t2 ON (t1.c1 = t2.c1) ORDER BY t1.
(10 rows)
-- full outer join with restrictions on the joining relations
EXPLAIN (VERBOSE, COSTS OFF)
SELECT t1.c1, t2.c1 FROM (SELECT c1 FROM ft4 WHERE c1 between 50 and 60) t1 FULL JOIN (SELECT c1 FROM ft5 WHERE c1 between 50 and 60) t2 ON (t1.c1 = t2.c1) ORDER BY t1.c1, t2.c1;
! QUERY PLAN
! ------------------------------------------------------------------------------------------------
! Sort
Output: ft4.c1, ft5.c1
! Sort Key: ft4.c1, ft5.c1
! -> Hash Full Join
! Output: ft4.c1, ft5.c1
! Hash Cond: (ft4.c1 = ft5.c1)
! -> Foreign Scan on public.ft4
! Output: ft4.c1, ft4.c2, ft4.c3
! Remote SQL: SELECT c1 FROM "S 1"."T 3" WHERE ((c1 >= 50)) AND ((c1 <= 60))
! -> Hash
! Output: ft5.c1
! -> Foreign Scan on public.ft5
! Output: ft5.c1
! Remote SQL: SELECT c1 FROM "S 1"."T 4" WHERE ((c1 >= 50)) AND ((c1 <= 60))
! (14 rows)
SELECT t1.c1, t2.c1 FROM (SELECT c1 FROM ft4 WHERE c1 between 50 and 60) t1 FULL JOIN (SELECT c1 FROM ft5 WHERE c1 between 50 and 60) t2 ON (t1.c1 = t2.c1) ORDER BY t1.c1, t2.c1;
c1 | c1
--- 1217,1232 ----
(10 rows)
-- full outer join with restrictions on the joining relations
+ -- a. the joining relations are both base relations
EXPLAIN (VERBOSE, COSTS OFF)
SELECT t1.c1, t2.c1 FROM (SELECT c1 FROM ft4 WHERE c1 between 50 and 60) t1 FULL JOIN (SELECT c1 FROM ft5 WHERE c1 between 50 and 60) t2 ON (t1.c1 = t2.c1) ORDER BY t1.c1, t2.c1;
! QUERY PLAN
! -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
! Foreign Scan
Output: ft4.c1, ft5.c1
! Relations: (public.ft4) FULL JOIN (public.ft5)
! Remote SQL: SELECT s4.c1, s5.c1 FROM ((SELECT c1 FROM "S 1"."T 3" WHERE ((c1 >= 50)) AND ((c1 <= 60))) s4(c1) FULL JOIN (SELECT c1 FROM "S 1"."T 4" WHERE ((c1 >= 50)) AND ((c1 <= 60))) s5(c1) ON (((s4.c1 = s5.c1)))) ORDER BY s4.c1 ASC NULLS LAST, s5.c1 ASC NULLS LAST
! (4 rows)
SELECT t1.c1, t2.c1 FROM (SELECT c1 FROM ft4 WHERE c1 between 50 and 60) t1 FULL JOIN (SELECT c1 FROM ft5 WHERE c1 between 50 and 60) t2 ON (t1.c1 = t2.c1) ORDER BY t1.c1, t2.c1;
c1 | c1
***************
*** 1250,1255 **** SELECT t1.c1, t2.c1 FROM (SELECT c1 FROM ft4 WHERE c1 between 50 and 60) t1 FULL
--- 1241,1332 ----
| 57
(8 rows)
+ EXPLAIN (VERBOSE, COSTS OFF)
+ SELECT 1 FROM (SELECT c1 FROM ft4 WHERE c1 between 50 and 60) t1 FULL JOIN (SELECT c1 FROM ft5 WHERE c1 between 50 and 60) t2 ON (TRUE);
+ QUERY PLAN
+ --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ Foreign Scan
+ Output: 1
+ Relations: (public.ft4) FULL JOIN (public.ft5)
+ Remote SQL: SELECT NULL FROM ((SELECT NULL FROM "S 1"."T 3" WHERE ((c1 >= 50)) AND ((c1 <= 60))) s4 FULL JOIN (SELECT NULL FROM "S 1"."T 4" WHERE ((c1 >= 50)) AND ((c1 <= 60))) s5 ON (TRUE))
+ (4 rows)
+
+ SELECT 1 FROM (SELECT c1 FROM ft4 WHERE c1 between 50 and 60) t1 FULL JOIN (SELECT c1 FROM ft5 WHERE c1 between 50 and 60) t2 ON (TRUE);
+ ?column?
+ ----------
+ 1
+ 1
+ 1
+ 1
+ 1
+ 1
+ 1
+ 1
+ 1
+ 1
+ 1
+ 1
+ 1
+ 1
+ 1
+ 1
+ 1
+ 1
+ 1
+ 1
+ 1
+ 1
+ 1
+ 1
+ (24 rows)
+
+ -- b. one of the joining relations is a base relation and the other is a join
+ -- relation
+ EXPLAIN (VERBOSE, COSTS OFF)
+ SELECT t1.c1, ss.a, ss.b FROM (SELECT c1 FROM ft4 WHERE c1 between 50 and 60) t1 FULL JOIN (SELECT t2.c1, t3.c1 FROM ft4 t2 LEFT JOIN ft5 t3 ON (t2.c1 = t3.c1) WHERE (t2.c1 between 50 and 60)) ss(a, b) ON (t1.c1 = ss.a) ORDER BY t1.c1, ss.a, ss.b;
+ QUERY PLAN
+ -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ Foreign Scan
+ Output: ft4.c1, t2.c1, t3.c1
+ Relations: (public.ft4) FULL JOIN ((public.ft4 t2) LEFT JOIN (public.ft5 t3))
+ Remote SQL: SELECT s4.c1, s8.c1, s8.c2 FROM ((SELECT c1 FROM "S 1"."T 3" WHERE ((c1 >= 50)) AND ((c1 <= 60))) s4(c1) FULL JOIN (SELECT r5.c1, r6.c1 FROM ("S 1"."T 3" r5 LEFT JOIN "S 1"."T 4" r6 ON (((r5.c1 = r6.c1)))) WHERE ((r5.c1 >= 50)) AND ((r5.c1 <= 60))) s8(c1, c2) ON (((s4.c1 = s8.c1)))) ORDER BY s4.c1 ASC NULLS LAST, s8.c1 ASC NULLS LAST, s8.c2 ASC NULLS LAST
+ (4 rows)
+
+ SELECT t1.c1, ss.a, ss.b FROM (SELECT c1 FROM ft4 WHERE c1 between 50 and 60) t1 FULL JOIN (SELECT t2.c1, t3.c1 FROM ft4 t2 LEFT JOIN ft5 t3 ON (t2.c1 = t3.c1) WHERE (t2.c1 between 50 and 60)) ss(a, b) ON (t1.c1 = ss.a) ORDER BY t1.c1, ss.a, ss.b;
+ c1 | a | b
+ ----+----+----
+ 50 | 50 |
+ 52 | 52 |
+ 54 | 54 | 54
+ 56 | 56 |
+ 58 | 58 |
+ 60 | 60 | 60
+ (6 rows)
+
+ -- c. test deparsing the remote query as nested subqueries
+ EXPLAIN (VERBOSE, COSTS OFF)
+ SELECT t1.c1, ss.a, ss.b FROM (SELECT c1 FROM ft4 WHERE c1 between 50 and 60) t1 FULL JOIN (SELECT t2.c1, t3.c1 FROM (SELECT c1 FROM ft4 WHERE c1 between 50 and 60) t2 FULL JOIN (SELECT c1 FROM ft5 WHERE c1 between 50 and 60) t3 ON (t2.c1 = t3.c1) WHERE t2.c1 IS NULL OR t2.c1 IS NOT NULL) ss(a, b) ON (t1.c1 = ss.a) ORDER BY t1.c1, ss.a, ss.b;
+ QUERY PLAN
+ --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ Foreign Scan
+ Output: ft4.c1, ft4_1.c1, ft5.c1
+ Relations: (public.ft4) FULL JOIN ((public.ft4) FULL JOIN (public.ft5))
+ Remote SQL: SELECT s4.c1, s10.c1, s10.c2 FROM ((SELECT c1 FROM "S 1"."T 3" WHERE ((c1 >= 50)) AND ((c1 <= 60))) s4(c1) FULL JOIN (SELECT s8.c1, s9.c1 FROM ((SELECT c1 FROM "S 1"."T 3" WHERE ((c1 >= 50)) AND ((c1 <= 60))) s8(c1) FULL JOIN (SELECT c1 FROM "S 1"."T 4" WHERE ((c1 >= 50)) AND ((c1 <= 60))) s9(c1) ON (((s8.c1 = s9.c1)))) WHERE (((s8.c1 IS NULL) OR (s8.c1 IS NOT NULL)))) s10(c1, c2) ON (((s4.c1 = s10.c1)))) ORDER BY s4.c1 ASC NULLS LAST, s10.c1 ASC NULLS LAST, s10.c2 ASC NULLS LAST
+ (4 rows)
+
+ SELECT t1.c1, ss.a, ss.b FROM (SELECT c1 FROM ft4 WHERE c1 between 50 and 60) t1 FULL JOIN (SELECT t2.c1, t3.c1 FROM (SELECT c1 FROM ft4 WHERE c1 between 50 and 60) t2 FULL JOIN (SELECT c1 FROM ft5 WHERE c1 between 50 and 60) t3 ON (t2.c1 = t3.c1) WHERE t2.c1 IS NULL OR t2.c1 IS NOT NULL) ss(a, b) ON (t1.c1 = ss.a) ORDER BY t1.c1, ss.a, ss.b;
+ c1 | a | b
+ ----+----+----
+ 50 | 50 |
+ 52 | 52 |
+ 54 | 54 | 54
+ 56 | 56 |
+ 58 | 58 |
+ 60 | 60 | 60
+ | | 51
+ | | 57
+ (8 rows)
+
-- full outer join + inner join
EXPLAIN (VERBOSE, COSTS OFF)
SELECT t1.c1, t2.c1, t3.c1 FROM ft4 t1 INNER JOIN ft5 t2 ON (t1.c1 = t2.c1 + 1 and t1.c1 between 50 and 60) FULL JOIN ft4 t3 ON (t2.c1 = t3.c1) ORDER BY t1.c1, t2.c1, t3.c1 LIMIT 10;
***************
*** 3062,3067 **** select avg(t1.c1), sum(t2.c1) from ft4 t1 full join ft5 t2 on (t1.c1 = t2.c1) gr
--- 3139,3162 ----
| 9
(3 rows)
+ -- Aggregate over FULL join needing to deparse the joining relations as
+ -- subqueries.
+ explain (verbose, costs off)
+ select count(*), sum(t1.c1), avg(t2.c1) from (select c1 from ft4 where c1 between 50 and 60) t1 full join (select c1 from ft5 where c1 between 50 and 60) t2 on (t1.c1 = t2.c1);
+ QUERY PLAN
+ -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ Foreign Scan
+ Output: (count(*)), (sum(ft4.c1)), (avg(ft5.c1))
+ Relations: Aggregate on ((public.ft4) FULL JOIN (public.ft5))
+ Remote SQL: SELECT count(*), sum(s4.c1), avg(s5.c1) FROM ((SELECT c1 FROM "S 1"."T 3" WHERE ((c1 >= 50)) AND ((c1 <= 60))) s4(c1) FULL JOIN (SELECT c1 FROM "S 1"."T 4" WHERE ((c1 >= 50)) AND ((c1 <= 60))) s5(c1) ON (((s4.c1 = s5.c1))))
+ (4 rows)
+
+ select count(*), sum(t1.c1), avg(t2.c1) from (select c1 from ft4 where c1 between 50 and 60) t1 full join (select c1 from ft5 where c1 between 50 and 60) t2 on (t1.c1 = t2.c1);
+ count | sum | avg
+ -------+-----+---------------------
+ 8 | 330 | 55.5000000000000000
+ (1 row)
+
-- ORDER BY expression is part of the target list but not pushed down to
-- foreign server.
explain (verbose, costs off)
*** a/contrib/postgres_fdw/postgres_fdw.c
--- b/contrib/postgres_fdw/postgres_fdw.c
***************
*** 668,673 **** postgresGetForeignRelSize(PlannerInfo *root,
--- 668,680 ----
if (*refname && strcmp(refname, relname) != 0)
appendStringInfo(fpinfo->relation_name, " %s",
quote_identifier(rte->eref->aliasname));
+
+ /* Initialize info about whether to deparse this rel as a subquery. */
+ fpinfo->is_subquery_rel = false;
+ /* Initialize info about lower subqueries. */
+ fpinfo->lower_subquery_rels = NULL;
+ /* Set the relation index. */
+ fpinfo->relation_index = baserel->relid;
}
/*
***************
*** 4146,4156 **** foreign_join_ok(PlannerInfo *root, RelOptInfo *joinrel, JoinType jointype,
fpinfo->innerrel = innerrel;
fpinfo->jointype = jointype;
/*
* Pull the other remote conditions from the joining relations into join
* clauses or other remote clauses (remote_conds) of this relation
! * wherever possible. This avoids building subqueries at every join step,
! * which is not currently supported by the deparser logic.
*
* For an inner join, clauses from both the relations are added to the
* other remote clauses. For LEFT and RIGHT OUTER join, the clauses from
--- 4153,4176 ----
fpinfo->innerrel = innerrel;
fpinfo->jointype = jointype;
+ /* Initialize info about whether to deparse this rel as a subquery. */
+ fpinfo->is_subquery_rel = false;
+
+ /*
+ * By default both the joining relations are not required to be deparsed as
+ * subqueries. But there might be some relations covered by the joining
+ * relations that are required to be deparsed as subqueries, so save the
+ * relids of those relations for later use by the deparser.
+ */
+ Assert(bms_is_subset(fpinfo_i->lower_subquery_rels, innerrel->relids));
+ Assert(bms_is_subset(fpinfo_o->lower_subquery_rels, outerrel->relids));
+ fpinfo->lower_subquery_rels = bms_union(fpinfo_i->lower_subquery_rels,
+ fpinfo_o->lower_subquery_rels);
+
/*
* Pull the other remote conditions from the joining relations into join
* clauses or other remote clauses (remote_conds) of this relation
! * wherever possible. This avoids building subqueries at every join step.
*
* For an inner join, clauses from both the relations are added to the
* other remote clauses. For LEFT and RIGHT OUTER join, the clauses from
***************
*** 4161,4168 **** foreign_join_ok(PlannerInfo *root, RelOptInfo *joinrel, JoinType jointype,
*
* For a FULL OUTER JOIN, the other clauses from either relation can not
* be added to the joinclauses or remote_conds, since each relation acts
! * as an outer relation for the other. Consider such full outer join as
! * unshippable because of the reasons mentioned above in this comment.
*
* The joining sides can not have local conditions, thus no need to test
* shippability of the clauses being pulled up.
--- 4181,4187 ----
*
* For a FULL OUTER JOIN, the other clauses from either relation can not
* be added to the joinclauses or remote_conds, since each relation acts
! * as an outer relation for the other.
*
* The joining sides can not have local conditions, thus no need to test
* shippability of the clauses being pulled up.
***************
*** 4191,4198 **** foreign_join_ok(PlannerInfo *root, RelOptInfo *joinrel, JoinType jointype,
break;
case JOIN_FULL:
! if (fpinfo_i->remote_conds || fpinfo_o->remote_conds)
! return false;
break;
default:
--- 4210,4238 ----
break;
case JOIN_FULL:
!
! /*
! * In this case, if any of the joining relations has conditions,
! * we need to deparse that relation as a subquery so that the
! * conditions can be evaluated before the join. Remember it in
! * the fpinfo so that the deparser can take appropriate action.
! * We also save the relids of the base relations covered by the
! * joining relation.
! */
! if (fpinfo_o->remote_conds)
! {
! fpinfo_o->is_subquery_rel = true;
! fpinfo->lower_subquery_rels =
! bms_add_members(fpinfo->lower_subquery_rels,
! outerrel->relids);
! }
! if (fpinfo_i->remote_conds)
! {
! fpinfo_i->is_subquery_rel = true;
! fpinfo->lower_subquery_rels =
! bms_add_members(fpinfo->lower_subquery_rels,
! innerrel->relids);
! }
break;
default:
***************
*** 4273,4278 **** foreign_join_ok(PlannerInfo *root, RelOptInfo *joinrel, JoinType jointype,
--- 4313,4328 ----
get_jointype_name(fpinfo->jointype),
fpinfo_i->relation_name->data);
+ /*
+ * Set the relation index. This is defined as the position of this
+ * joinrel in the join_rel_list list plus the length of the rtable list.
+ * Note that since this joinrel is at the end of the list when we are
+ * called, we can get the position by list_length.
+ */
+ Assert(fpinfo->relation_index == 0);
+ fpinfo->relation_index =
+ list_length(root->parse->rtable) + list_length(root->join_rel_list);
+
return true;
}
*** a/contrib/postgres_fdw/postgres_fdw.h
--- b/contrib/postgres_fdw/postgres_fdw.h
***************
*** 95,100 **** typedef struct PgFdwRelationInfo
--- 95,110 ----
/* Grouping information */
List *grouped_tlist;
+
+ /* Subquery information */
+ bool is_subquery_rel; /* do we deparse this as a subquery? */
+ Relids lower_subquery_rels; /* all relids appearing in lower
+ * subqueries */
+ /*
+ * Index of the relation. It is used for creating a subselect alias when
+ * the is_subquery_rel is true.
+ */
+ int relation_index;
} PgFdwRelationInfo;
/* in postgres_fdw.c */
*** a/contrib/postgres_fdw/sql/postgres_fdw.sql
--- b/contrib/postgres_fdw/sql/postgres_fdw.sql
***************
*** 391,399 **** EXPLAIN (VERBOSE, COSTS OFF)
--- 391,412 ----
SELECT t1.c1, t2.c1 FROM ft4 t1 FULL JOIN ft5 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c1, t2.c1 OFFSET 45 LIMIT 10;
SELECT t1.c1, t2.c1 FROM ft4 t1 FULL JOIN ft5 t2 ON (t1.c1 = t2.c1) ORDER BY t1.c1, t2.c1 OFFSET 45 LIMIT 10;
-- full outer join with restrictions on the joining relations
+ -- a. the joining relations are both base relations
EXPLAIN (VERBOSE, COSTS OFF)
SELECT t1.c1, t2.c1 FROM (SELECT c1 FROM ft4 WHERE c1 between 50 and 60) t1 FULL JOIN (SELECT c1 FROM ft5 WHERE c1 between 50 and 60) t2 ON (t1.c1 = t2.c1) ORDER BY t1.c1, t2.c1;
SELECT t1.c1, t2.c1 FROM (SELECT c1 FROM ft4 WHERE c1 between 50 and 60) t1 FULL JOIN (SELECT c1 FROM ft5 WHERE c1 between 50 and 60) t2 ON (t1.c1 = t2.c1) ORDER BY t1.c1, t2.c1;
+ EXPLAIN (VERBOSE, COSTS OFF)
+ SELECT 1 FROM (SELECT c1 FROM ft4 WHERE c1 between 50 and 60) t1 FULL JOIN (SELECT c1 FROM ft5 WHERE c1 between 50 and 60) t2 ON (TRUE);
+ SELECT 1 FROM (SELECT c1 FROM ft4 WHERE c1 between 50 and 60) t1 FULL JOIN (SELECT c1 FROM ft5 WHERE c1 between 50 and 60) t2 ON (TRUE);
+ -- b. one of the joining relations is a base relation and the other is a join
+ -- relation
+ EXPLAIN (VERBOSE, COSTS OFF)
+ SELECT t1.c1, ss.a, ss.b FROM (SELECT c1 FROM ft4 WHERE c1 between 50 and 60) t1 FULL JOIN (SELECT t2.c1, t3.c1 FROM ft4 t2 LEFT JOIN ft5 t3 ON (t2.c1 = t3.c1) WHERE (t2.c1 between 50 and 60)) ss(a, b) ON (t1.c1 = ss.a) ORDER BY t1.c1, ss.a, ss.b;
+ SELECT t1.c1, ss.a, ss.b FROM (SELECT c1 FROM ft4 WHERE c1 between 50 and 60) t1 FULL JOIN (SELECT t2.c1, t3.c1 FROM ft4 t2 LEFT JOIN ft5 t3 ON (t2.c1 = t3.c1) WHERE (t2.c1 between 50 and 60)) ss(a, b) ON (t1.c1 = ss.a) ORDER BY t1.c1, ss.a, ss.b;
+ -- c. test deparsing the remote query as nested subqueries
+ EXPLAIN (VERBOSE, COSTS OFF)
+ SELECT t1.c1, ss.a, ss.b FROM (SELECT c1 FROM ft4 WHERE c1 between 50 and 60) t1 FULL JOIN (SELECT t2.c1, t3.c1 FROM (SELECT c1 FROM ft4 WHERE c1 between 50 and 60) t2 FULL JOIN (SELECT c1 FROM ft5 WHERE c1 between 50 and 60) t3 ON (t2.c1 = t3.c1) WHERE t2.c1 IS NULL OR t2.c1 IS NOT NULL) ss(a, b) ON (t1.c1 = ss.a) ORDER BY t1.c1, ss.a, ss.b;
+ SELECT t1.c1, ss.a, ss.b FROM (SELECT c1 FROM ft4 WHERE c1 between 50 and 60) t1 FULL JOIN (SELECT t2.c1, t3.c1 FROM (SELECT c1 FROM ft4 WHERE c1 between 50 and 60) t2 FULL JOIN (SELECT c1 FROM ft5 WHERE c1 between 50 and 60) t3 ON (t2.c1 = t3.c1) WHERE t2.c1 IS NULL OR t2.c1 IS NOT NULL) ss(a, b) ON (t1.c1 = ss.a) ORDER BY t1.c1, ss.a, ss.b;
-- full outer join + inner join
EXPLAIN (VERBOSE, COSTS OFF)
SELECT t1.c1, t2.c1, t3.c1 FROM ft4 t1 INNER JOIN ft5 t2 ON (t1.c1 = t2.c1 + 1 and t1.c1 between 50 and 60) FULL JOIN ft4 t3 ON (t2.c1 = t3.c1) ORDER BY t1.c1, t2.c1, t3.c1 LIMIT 10;
***************
*** 793,798 **** explain (verbose, costs off)
--- 806,817 ----
select avg(t1.c1), sum(t2.c1) from ft4 t1 full join ft5 t2 on (t1.c1 = t2.c1) group by t2.c1 having (avg(t1.c1) is null and sum(t2.c1) < 10) or sum(t2.c1) is null order by 1 nulls last, 2;
select avg(t1.c1), sum(t2.c1) from ft4 t1 full join ft5 t2 on (t1.c1 = t2.c1) group by t2.c1 having (avg(t1.c1) is null and sum(t2.c1) < 10) or sum(t2.c1) is null order by 1 nulls last, 2;
+ -- Aggregate over FULL join needing to deparse the joining relations as
+ -- subqueries.
+ explain (verbose, costs off)
+ select count(*), sum(t1.c1), avg(t2.c1) from (select c1 from ft4 where c1 between 50 and 60) t1 full join (select c1 from ft5 where c1 between 50 and 60) t2 on (t1.c1 = t2.c1);
+ select count(*), sum(t1.c1), avg(t2.c1) from (select c1 from ft4 where c1 between 50 and 60) t1 full join (select c1 from ft5 where c1 between 50 and 60) t2 on (t1.c1 = t2.c1);
+
-- ORDER BY expression is part of the target list but not pushed down to
-- foreign server.
explain (verbose, costs off)
--
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