On 2016/11/04 13:08, Ashutosh Bapat wrote:
On Fri, Nov 4, 2016 at 9:19 AM, Etsuro Fujita
<fujita.ets...@lab.ntt.co.jp> wrote:
On 2016/11/03 18:52, Ashutosh Bapat wrote:
I wrote:
Here is the updated version,
Other than the above issue and the alias issue we discussed, I addressed
all
your comments except one on testing; I tried to add test cases where the
remote query is deparsed as nested subqueries, but I couldn't because
IIUC,
reduce_outer_joins reduced full joins to inner joins or left joins.
No always. It will do so in some cases as explained in the prologue of
reduce_outer_joins()
* More generally, an outer join can be reduced in strength if there is a
* strict qual above it in the qual tree that constrains a Var from the
* nullable side of the join to be non-null. (For FULL joins this applies
* to each side separately.)
Right.
Would it be necessary for this patch to include test cases for nested
subqueries?
A patch should have testcases testing the functionality added. This
patch adds functionality to deparse nested subqueries, so there should
be testcase to test it.
OK, I added such a test case.
This patch again has a lot of unrelated changes, esp. in
deparseSelectStmtForRel(). What was earlier part of deparseSelectSql()
and deparseFromExpr() is now flattened in deparseSelectStmtForRel(),
which seems unnecessary.
IIUC, I think this change was done to address your comment (see the comment
#2 in [1]). Am I missing something?
There is some misunderstanding here. That comment basically says,
deparseRangeTblRef() duplicates code in deparseSelectStmtForRel(), so
we should either remove deparseRangeTblRef() altogether or should keep
it to minimal avoiding duplication of code. What might have confused
you is the last sentence in that comment "This will also make the
current changes to deparseSelectSql unnecessary." By current changes I
meant changes to deparseSelectSql() in your patch, not the one that's
in the repository. I don't think we should flatten
deparseSelectStmtForRel() in this patch.
I noticed that I misunderstood your words. Sorry about that. I agree
with you, so I removed that change from the patch.
Attached is an updated version of the patch.
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_TAB_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);
--- 169,180 ----
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,
+ bool make_subquery, List **params_list);
+ static void appendSubselectAlias(StringInfo buf, int tabno, int ncols);
+ static void getSubselectAliasInfo(Var *node, RelOptInfo *foreignrel,
+ int *tabno, int *colno);
+ static bool isSubqueryExpr(Var *node, RelOptInfo *foreignrel, int *tabno, 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,
***************
*** 1155,1165 **** deparseLockingClause(deparse_expr_cxt *context)
--- 1163,1182 ----
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, because in that
+ * case we would have already considered locking for the relation
+ * while deparsing the lower subquery.
+ */
+ if (bms_is_member(relid, fpinfo->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
--- 1364,1385 ----
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,
! fpinfo->make_outerrel_subquery,
! params_list);
/* Deparse inner relation */
initStringInfo(&join_sql_i);
! deparseRangeTblRef(&join_sql_i, root,
! fpinfo->innerrel,
! fpinfo->make_innerrel_subquery,
! params_list);
/*
* For a join relation FROM clause entry is deparsed as
***************
*** 1414,1419 **** deparseFromExprForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
--- 1435,1585 ----
}
/*
+ * Append operand relation of foreign join to buf.
+ */
+ static void
+ deparseRangeTblRef(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
+ bool make_subquery, List **params_list)
+ {
+ PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
+
+ Assert(foreignrel->reloptkind == RELOPT_BASEREL ||
+ foreignrel->reloptkind == RELOPT_JOINREL);
+ Assert(fpinfo->local_conds == NIL);
+
+ if (make_subquery)
+ {
+ List *tlist;
+ List *retrieved_attrs;
+
+ tlist = make_tlist_from_pathtarget(foreignrel->reltarget);
+ Assert(tlist != NIL);
+ appendStringInfoChar(buf, '(');
+ deparseSelectStmtForRel(buf, root, foreignrel, tlist,
+ fpinfo->remote_conds, NIL,
+ &retrieved_attrs, params_list);
+ appendStringInfoChar(buf, ')');
+ appendSubselectAlias(buf, fpinfo->relation_index,
+ list_length(foreignrel->reltarget->exprs));
+ }
+ else
+ deparseFromExprForRel(buf, root, foreignrel, true, params_list);
+ }
+
+ /*
+ * Add a subselect alias to a subquery-in-FROM.
+ *
+ * The table alias and column aliases are appended to buf. tabno is the index
+ * for the table alias, and ncols is the number of the column aliases to add.
+ * (The indexes for the column aliases are 1..ncols.)
+ */
+ static void
+ appendSubselectAlias(StringInfo buf, int tabno, int ncols)
+ {
+ int i;
+
+ /* Append the table alias */
+ appendStringInfo(buf, " %s%d", SS_TAB_ALIAS_PREFIX, tabno);
+
+ /* Append the column aliases */
+ 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 info about the subselect alias to given expression.
+ *
+ * The subselect table and column numbers are returned to *tabno and *colno,
+ * respectively.
+ */
+ static void
+ getSubselectAliasInfo(Var *node, RelOptInfo *foreignrel,
+ int *tabno, int *colno)
+ {
+ PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
+ int i;
+ ListCell *lc;
+
+ /* Get the table number */
+ *tabno = fpinfo->relation_index;
+
+ /* Get the column number */
+ 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 given expression is an output column of a subquery-in-FROM.
+ *
+ * The subselect table and column numbers are returned to *tabno and *colno,
+ * respectively, in that case.
+ */
+ static bool
+ isSubqueryExpr(Var *node, RelOptInfo *foreignrel, int *tabno, int *colno)
+ {
+ PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) foreignrel->fdw_private;
+ RelOptInfo *outerrel = fpinfo->outerrel;
+ RelOptInfo *innerrel = fpinfo->innerrel;
+
+ if (foreignrel->reloptkind != RELOPT_JOINREL)
+ return false;
+
+ if (!fpinfo->subquery_rels)
+ return false;
+
+ if (bms_is_member(node->varno, outerrel->relids))
+ {
+ /*
+ * If outer relation is deparsed as a subqeury, the given expression
+ * will be an output column of the subquery; get the subselect alias
+ * info for the given expression.
+ */
+ if (fpinfo->make_outerrel_subquery)
+ {
+ getSubselectAliasInfo(node, outerrel, tabno, colno);
+ return true;
+ }
+ /* Otherwise, recurse into outer relation */
+ if (isSubqueryExpr(node, outerrel, tabno, colno))
+ return true;
+ }
+ else
+ {
+ Assert(bms_is_member(node->varno, innerrel->relids));
+
+ /*
+ * Likewise for inner relation
+ */
+ if (fpinfo->make_innerrel_subquery)
+ {
+ getSubselectAliasInfo(node, innerrel, tabno, colno);
+ return true;
+ }
+ if (isSubqueryExpr(node, innerrel, tabno, colno))
+ return true;
+ }
+ return false;
+ }
+
+ /*
* deparse remote INSERT statement
*
* The statement text is appended to buf, and we also create an integer List
***************
*** 2057,2066 **** static void
--- 2223,2248 ----
deparseVar(Var *node, deparse_expr_cxt *context)
{
Relids relids = context->scanrel->relids;
+ RelOptInfo *rel = (context->foreignrel->reloptkind == RELOPT_UPPER_REL) ?
+ context->scanrel : context->foreignrel;
+ int tabno;
+ int colno;
/* Qualify columns when multiple relations are involved. */
bool qualify_col = (bms_num_members(relids) > 1);
+ /*
+ * If the given Var is an output column of a subquery-in-FROM, deparse
+ * the alias to the given Var instead.
+ */
+ if (isSubqueryExpr(node, rel, &tabno, &colno))
+ {
+ appendStringInfo(context->buf, "%s%d.%s%d",
+ SS_TAB_ALIAS_PREFIX, tabno,
+ 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
***************
*** 1250,1281 **** SELECT t1.c1, t2.c1 FROM (SELECT c1 FROM ft4 WHERE c1 between 50 and 60) t1 FULL
| 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;
! QUERY PLAN
! -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Limit
! Output: t1.c1, t2.c1, t3.c1
-> Foreign Scan
! Output: t1.c1, t2.c1, t3.c1
Relations: ((public.ft4 t1) INNER JOIN (public.ft5 t2)) FULL JOIN (public.ft4 t3)
! Remote SQL: SELECT r1.c1, r2.c1, r4.c1 FROM (("S 1"."T 3" r1 INNER JOIN "S 1"."T 4" r2 ON (((r1.c1 = (r2.c1 + 1))) AND ((r1.c1 >= 50)) AND ((r1.c1 <= 60)))) FULL JOIN "S 1"."T 3" r4 ON (((r2.c1 = r4.c1)))) ORDER BY r1.c1 ASC NULLS LAST, r2.c1 ASC NULLS LAST, r4.c1 ASC NULLS LAST
(6 rows)
! 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;
! c1 | c1 | c1
! ----+----+----
! 52 | 51 |
! 58 | 57 |
! | | 2
! | | 4
! | | 6
! | | 8
! | | 10
! | | 12
! | | 14
! | | 16
(10 rows)
-- full outer join three tables
--- 1241,1319 ----
| 57
(8 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, 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;
! QUERY PLAN
! -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Limit
! Output: t1.*, t1.c1, t2.c1, t3.c1
-> Foreign Scan
! Output: t1.*, t1.c1, t2.c1, t3.c1
Relations: ((public.ft4 t1) INNER JOIN (public.ft5 t2)) FULL JOIN (public.ft4 t3)
! Remote SQL: SELECT CASE WHEN (r1.*)::text IS NOT NULL THEN ROW(r1.c1, r1.c2, r1.c3) END, r1.c1, r2.c1, r4.c1 FROM (("S 1"."T 3" r1 INNER JOIN "S 1"."T 4" r2 ON (((r1.c1 = (r2.c1 + 1))) AND ((r1.c1 >= 50)) AND ((r1.c1 <= 60)))) FULL JOIN "S 1"."T 3" r4 ON (((r2.c1 = r4.c1)))) ORDER BY r1.c1 ASC NULLS LAST, r2.c1 ASC NULLS LAST, r4.c1 ASC NULLS LAST
(6 rows)
! SELECT t1, 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;
! t1 | c1 | c1 | c1
! ----------------+----+----+----
! (52,53,AAA052) | 52 | 51 |
! (58,59,AAA058) | 58 | 57 |
! | | | 2
! | | | 4
! | | | 6
! | | | 8
! | | | 10
! | | | 12
! | | | 14
! | | | 16
(10 rows)
-- full outer join three tables
***************
*** 3062,3067 **** select avg(t1.c1), sum(t2.c1) from ft4 t1 full join ft5 t2 on (t1.c1 = t2.c1) gr
--- 3100,3123 ----
| 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,
--- 668,681 ----
if (*refname && strcmp(refname, relname) != 0)
appendStringInfo(fpinfo->relation_name, " %s",
quote_identifier(rte->eref->aliasname));
+
+ /* Set the subquery information */
+ fpinfo->make_outerrel_subquery = false;
+ fpinfo->make_innerrel_subquery = false;
+ fpinfo->subquery_rels = NULL;
+
+ /* Set the relation index */
+ fpinfo->relation_index = baserel->relid;
}
/*
***************
*** 4147,4156 **** foreign_join_ok(PlannerInfo *root, RelOptInfo *joinrel, JoinType jointype,
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
--- 4155,4176 ----
fpinfo->jointype = jointype;
/*
+ * 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 of deparser.
+ */
+ fpinfo->make_outerrel_subquery = false;
+ fpinfo->make_innerrel_subquery = false;
+ Assert(bms_is_subset(fpinfo_i->subquery_rels, innerrel->relids));
+ Assert(bms_is_subset(fpinfo_o->subquery_rels, outerrel->relids));
+ fpinfo->subquery_rels = bms_union(fpinfo_i->subquery_rels,
+ fpinfo_o->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:
--- 4210,4236 ----
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
! * conditions can be evaluated before the join. Remember it in
! * the fpinfo so that deparser can take appropriate action. We
! * also save the relids of that relation that is covered by the
! * subquery for later use of deparser.
! */
! if (fpinfo_o->remote_conds)
! {
! fpinfo->make_outerrel_subquery = true;
! fpinfo->subquery_rels = bms_add_members(fpinfo->subquery_rels,
! outerrel->relids);
! }
! if (fpinfo_i->remote_conds)
! {
! fpinfo->make_innerrel_subquery = true;
! fpinfo->subquery_rels = bms_add_members(fpinfo->subquery_rels,
! innerrel->relids);
! }
break;
default:
***************
*** 4273,4278 **** foreign_join_ok(PlannerInfo *root, RelOptInfo *joinrel, JoinType jointype,
--- 4311,4326 ----
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
--- 95,113 ----
/* Grouping information */
List *grouped_tlist;
+
+ /* Subquery information */
+ bool make_outerrel_subquery; /* do we deparse outerrel as a
+ * subquery? */
+ bool make_innerrel_subquery; /* do we deparse innerrel as a
+ * subquery? */
+ Relids subquery_rels; /* all relids appearing in lower subqueries */
+
+ /*
+ * Index of the relation. It is used for creating a subselect alias when
+ * deparsing the relation as a subquery.
+ */
+ int relation_index;
} PgFdwRelationInfo;
/* in postgres_fdw.c */
*** a/contrib/postgres_fdw/sql/postgres_fdw.sql
--- b/contrib/postgres_fdw/sql/postgres_fdw.sql
***************
*** 391,403 **** EXPLAIN (VERBOSE, COSTS OFF)
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
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;
-- 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;
! 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;
-- full outer join three tables
EXPLAIN (VERBOSE, COSTS OFF)
SELECT t1.c1, t2.c2, t3.c3 FROM ft2 t1 FULL JOIN ft2 t2 ON (t1.c1 = t2.c1) FULL JOIN ft4 t3 ON (t2.c1 = t3.c1) OFFSET 10 LIMIT 10;
--- 391,413 ----
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;
+ -- 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, 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;
! SELECT t1, 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;
-- full outer join three tables
EXPLAIN (VERBOSE, COSTS OFF)
SELECT t1.c1, t2.c2, t3.c3 FROM ft2 t1 FULL JOIN ft2 t2 ON (t1.c1 = t2.c1) FULL JOIN ft4 t3 ON (t2.c1 = t3.c1) OFFSET 10 LIMIT 10;
***************
*** 793,798 **** explain (verbose, costs off)
--- 803,814 ----
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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