open-dsi
/
postgres
mirror of https://github.com/postgres/postgres
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

postgres_fdw: Perform the (ORDERED, NULL) upperrel operations remotely.

Browse Source 
The upper-planner pathification allows FDWs to arrange to push down
different types of upper-stage operations to the remote side.  This
commit teaches postgres_fdw to do it for the (ORDERED, NULL) upperrel,
which is responsible for evaluating the query's ORDER BY ordering.
Since postgres_fdw is already able to evaluate that ordering remotely
for foreign baserels and foreign joinrels (see commit aa09cd242f et al.),
this adds support for that for foreign grouping relations.

Author: Etsuro Fujita
Reviewed-By: Antonin Houska and Jeff Janes
Discussion: https://postgr.es/m/87pnz1aby9.fsf@news-spur.riddles.org.uk
pull/40/head
Etsuro Fujita 6 years ago
parent e2d28c0f40
commit ffab494a4d
4 changed files with 457 additions and 138 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
Show Stats Download Patch File Download Diff File
  1. 28
      contrib/postgres_fdw/deparse.c
  2. 167
      contrib/postgres_fdw/expected/postgres_fdw.out
  3. 388
      contrib/postgres_fdw/postgres_fdw.c
  4. 12
      contrib/postgres_fdw/postgres_fdw.h

28
contrib/postgres_fdw/deparse.c
Unescape View File

@ -167,7 +167,8 @@ static void printRemotePlaceholder(Oid paramtype, int32 paramtypmod,
static void deparseSelectSql(List *tlist, bool is_subquery, List **retrieved_attrs,
deparse_expr_cxt *context);
static void deparseLockingClause(deparse_expr_cxt *context);
static void appendOrderByClause(List *pathkeys, deparse_expr_cxt *context);
static void appendOrderByClause(List *pathkeys, bool has_final_sort,
deparse_expr_cxt *context);
static void appendConditions(List *exprs, deparse_expr_cxt *context);
static void deparseFromExprForRel(StringInfo buf, PlannerInfo *root,
RelOptInfo *foreignrel, bool use_alias,
@ -929,8 +930,8 @@ build_tlist_to_deparse(RelOptInfo *foreignrel)
void
deparseSelectStmtForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *rel,
List *tlist, List *remote_conds, List *pathkeys,
bool is_subquery, List **retrieved_attrs,
List **params_list)
bool has_final_sort, bool is_subquery,
List **retrieved_attrs, List **params_list)
{
deparse_expr_cxt context;
PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *) rel->fdw_private;
@ -985,7 +986,7 @@ deparseSelectStmtForRel(StringInfo buf, PlannerInfo *root, RelOptInfo *rel,
/* Add ORDER BY clause if we found any useful pathkeys */
if (pathkeys)
appendOrderByClause(pathkeys, &context);
appendOrderByClause(pathkeys, has_final_sort, &context);
/* Add any necessary FOR UPDATE/SHARE. */
deparseLockingClause(&context);
@ -1590,7 +1591,7 @@ deparseRangeTblRef(StringInfo buf, PlannerInfo *root, RelOptInfo *foreignrel,
/* Deparse the subquery representing the relation. */
appendStringInfoChar(buf, '(');
deparseSelectStmtForRel(buf, root, foreignrel, NIL,
fpinfo->remote_conds, NIL, true,
fpinfo->remote_conds, NIL, false, true,
&retrieved_attrs, params_list);
appendStringInfoChar(buf, ')');
@ -3109,7 +3110,8 @@ appendGroupByClause(List *tlist, deparse_expr_cxt *context)
* base relation are obtained and deparsed.
*/
static void
appendOrderByClause(List *pathkeys, deparse_expr_cxt *context)
appendOrderByClause(List *pathkeys, bool has_final_sort,
deparse_expr_cxt *context)
{
ListCell *lcell;
int nestlevel;
@ -3126,7 +3128,19 @@ appendOrderByClause(List *pathkeys, deparse_expr_cxt *context)
PathKey *pathkey = lfirst(lcell);
Expr *em_expr;
em_expr = find_em_expr_for_rel(pathkey->pk_eclass, baserel);
if (has_final_sort)
{
/*
* By construction, context->foreignrel is the input relation to
* the final sort.
*/
em_expr = find_em_expr_for_input_target(context->root,
pathkey->pk_eclass,
context->foreignrel->reltarget);
}
else
em_expr = find_em_expr_for_rel(pathkey->pk_eclass, baserel);
Assert(em_expr != NULL);
appendStringInfoString(buf, delim);

167
contrib/postgres_fdw/expected/postgres_fdw.out
Unescape View File

@ -2552,18 +2552,13 @@ DROP ROLE regress_view_owner;
-- Simple aggregates
explain (verbose, costs off)
select count(c6), sum(c1), avg(c1), min(c2), max(c1), stddev(c2), sum(c1) * (random() <= 1)::int as sum2 from ft1 where c2 < 5 group by c2 order by 1, 2;
QUERY PLAN
------------------------------------------------------------------------------------------------------------------------------------------------------
Result
QUERY PLAN
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Foreign Scan
Output: (count(c6)), (sum(c1)), (avg(c1)), (min(c2)), (max(c1)), (stddev(c2)), ((sum(c1)) * ((random() <= '1'::double precision))::integer), c2
-> Sort
Output: (count(c6)), (sum(c1)), (avg(c1)), (min(c2)), (max(c1)), (stddev(c2)), c2
Sort Key: (count(ft1.c6)), (sum(ft1.c1))
-> Foreign Scan
Output: (count(c6)), (sum(c1)), (avg(c1)), (min(c2)), (max(c1)), (stddev(c2)), c2
Relations: Aggregate on (public.ft1)
Remote SQL: SELECT count(c6), sum("C 1"), avg("C 1"), min(c2), max("C 1"), stddev(c2), c2 FROM "S 1"."T 1" WHERE ((c2 < 5)) GROUP BY 7
(9 rows)
Relations: Aggregate on (public.ft1)
Remote SQL: SELECT count(c6), sum("C 1"), avg("C 1"), min(c2), max("C 1"), stddev(c2), c2 FROM "S 1"."T 1" WHERE ((c2 < 5)) GROUP BY 7 ORDER BY count(c6) ASC NULLS LAST, sum("C 1") ASC NULLS LAST
(4 rows)
select count(c6), sum(c1), avg(c1), min(c2), max(c1), stddev(c2), sum(c1) * (random() <= 1)::int as sum2 from ft1 where c2 < 5 group by c2 order by 1, 2;
count | sum | avg | min | max | stddev | sum2
@ -2621,16 +2616,13 @@ select sum(t1.c1), count(t2.c1) from ft1 t1 inner join ft2 t2 on (t1.c1 = t2.c1)
-- GROUP BY clause having expressions
explain (verbose, costs off)
select c2/2, sum(c2) * (c2/2) from ft1 group by c2/2 order by c2/2;
QUERY PLAN
---------------------------------------------------------------------------------------
Sort
QUERY PLAN
------------------------------------------------------------------------------------------------------------------
Foreign Scan
Output: ((c2 / 2)), ((sum(c2) * (c2 / 2)))
Sort Key: ((ft1.c2 / 2))
-> Foreign Scan
Output: ((c2 / 2)), ((sum(c2) * (c2 / 2)))
Relations: Aggregate on (public.ft1)
Remote SQL: SELECT (c2 / 2), (sum(c2) * (c2 / 2)) FROM "S 1"."T 1" GROUP BY 1
(7 rows)
Relations: Aggregate on (public.ft1)
Remote SQL: SELECT (c2 / 2), (sum(c2) * (c2 / 2)) FROM "S 1"."T 1" GROUP BY 1 ORDER BY (c2 / 2) ASC NULLS LAST
(4 rows)
select c2/2, sum(c2) * (c2/2) from ft1 group by c2/2 order by c2/2;
?column? | ?column?
@ -2645,18 +2637,15 @@ select c2/2, sum(c2) * (c2/2) from ft1 group by c2/2 order by c2/2;
-- Aggregates in subquery are pushed down.
explain (verbose, costs off)
select count(x.a), sum(x.a) from (select c2 a, sum(c1) b from ft1 group by c2, sqrt(c1) order by 1, 2) x;
QUERY PLAN
---------------------------------------------------------------------------------------------
QUERY PLAN
---------------------------------------------------------------------------------------------------------------------------------------------
Aggregate
Output: count(ft1.c2), sum(ft1.c2)
-> Sort
-> Foreign Scan
Output: ft1.c2, (sum(ft1.c1)), (sqrt((ft1.c1)::double precision))
Sort Key: ft1.c2, (sum(ft1.c1))
-> Foreign Scan
Output: ft1.c2, (sum(ft1.c1)), (sqrt((ft1.c1)::double precision))
Relations: Aggregate on (public.ft1)
Remote SQL: SELECT c2, sum("C 1"), sqrt("C 1") FROM "S 1"."T 1" GROUP BY 1, 3
(9 rows)
Relations: Aggregate on (public.ft1)
Remote SQL: SELECT c2, sum("C 1"), sqrt("C 1") FROM "S 1"."T 1" GROUP BY 1, 3 ORDER BY c2 ASC NULLS LAST, sum("C 1") ASC NULLS LAST
(6 rows)
select count(x.a), sum(x.a) from (select c2 a, sum(c1) b from ft1 group by c2, sqrt(c1) order by 1, 2) x;
count | sum
@ -2742,16 +2731,13 @@ select count(c2) w, c2 x, 5 y, 7.0 z from ft1 group by 2, y, 9.0::int order by 2
-- Also, ORDER BY contains an aggregate function
explain (verbose, costs off)
select c2, c2 from ft1 where c2 > 6 group by 1, 2 order by sum(c1);
QUERY PLAN
-----------------------------------------------------------------------------------------------
Sort
QUERY PLAN
----------------------------------------------------------------------------------------------------------------------------
Foreign Scan
Output: c2, c2, (sum(c1))
Sort Key: (sum(ft1.c1))
-> Foreign Scan
Output: c2, c2, (sum(c1))
Relations: Aggregate on (public.ft1)
Remote SQL: SELECT c2, c2, sum("C 1") FROM "S 1"."T 1" WHERE ((c2 > 6)) GROUP BY 1, 2
(7 rows)
Relations: Aggregate on (public.ft1)
Remote SQL: SELECT c2, c2, sum("C 1") FROM "S 1"."T 1" WHERE ((c2 > 6)) GROUP BY 1, 2 ORDER BY sum("C 1") ASC NULLS LAST
(4 rows)
select c2, c2 from ft1 where c2 > 6 group by 1, 2 order by sum(c1);
c2 | c2
@ -2764,16 +2750,13 @@ select c2, c2 from ft1 where c2 > 6 group by 1, 2 order by sum(c1);
-- Testing HAVING clause shippability
explain (verbose, costs off)
select c2, sum(c1) from ft2 group by c2 having avg(c1) < 500 and sum(c1) < 49800 order by c2;
QUERY PLAN
---------------------------------------------------------------------------------------------------------------------------------------
Sort
QUERY PLAN
------------------------------------------------------------------------------------------------------------------------------------------------------------
Foreign Scan
Output: c2, (sum(c1))
Sort Key: ft2.c2
-> Foreign Scan
Output: c2, (sum(c1))
Relations: Aggregate on (public.ft2)
Remote SQL: SELECT c2, sum("C 1") FROM "S 1"."T 1" GROUP BY 1 HAVING ((avg("C 1") < 500::numeric)) AND ((sum("C 1") < 49800))
(7 rows)
Relations: Aggregate on (public.ft2)
Remote SQL: SELECT c2, sum("C 1") FROM "S 1"."T 1" GROUP BY 1 HAVING ((avg("C 1") < 500::numeric)) AND ((sum("C 1") < 49800)) ORDER BY c2 ASC NULLS LAST
(4 rows)
select c2, sum(c1) from ft2 group by c2 having avg(c1) < 500 and sum(c1) < 49800 order by c2;
c2 | sum
@ -2823,16 +2806,13 @@ select sum(c1) from ft1 group by c2 having avg(c1 * (random() <= 1)::int) > 100
-- ORDER BY within aggregate, same column used to order
explain (verbose, costs off)
select array_agg(c1 order by c1) from ft1 where c1 < 100 group by c2 order by 1;
QUERY PLAN
---------------------------------------------------------------------------------------------------------------------------------
Sort
QUERY PLAN
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Foreign Scan
Output: (array_agg(c1 ORDER BY c1)), c2
Sort Key: (array_agg(ft1.c1 ORDER BY ft1.c1))
-> Foreign Scan
Output: (array_agg(c1 ORDER BY c1)), c2
Relations: Aggregate on (public.ft1)
Remote SQL: SELECT array_agg("C 1" ORDER BY "C 1" ASC NULLS LAST), c2 FROM "S 1"."T 1" WHERE (("C 1" < 100)) GROUP BY 2
(7 rows)
Relations: Aggregate on (public.ft1)
Remote SQL: SELECT array_agg("C 1" ORDER BY "C 1" ASC NULLS LAST), c2 FROM "S 1"."T 1" WHERE (("C 1" < 100)) GROUP BY 2 ORDER BY array_agg("C 1" ORDER BY "C 1" ASC NULLS LAST) ASC NULLS LAST
(4 rows)
select array_agg(c1 order by c1) from ft1 where c1 < 100 group by c2 order by 1;
array_agg
@ -2869,16 +2849,13 @@ select array_agg(c5 order by c1 desc) from ft2 where c2 = 6 and c1 < 50;
-- DISTINCT within aggregate
explain (verbose, costs off)
select array_agg(distinct (t1.c1)%5) from ft4 t1 full join ft5 t2 on (t1.c1 = t2.c1) where t1.c1 < 20 or (t1.c1 is null and t2.c1 < 5) group by (t2.c1)%3 order by 1;
QUERY PLAN
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Sort
QUERY PLAN
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Foreign Scan
Output: (array_agg(DISTINCT (t1.c1 % 5))), ((t2.c1 % 3))
Sort Key: (array_agg(DISTINCT (t1.c1 % 5)))
-> Foreign Scan
Output: (array_agg(DISTINCT (t1.c1 % 5))), ((t2.c1 % 3))
Relations: Aggregate on ((public.ft4 t1) FULL JOIN (public.ft5 t2))
Remote SQL: SELECT array_agg(DISTINCT (r1.c1 % 5)), (r2.c1 % 3) FROM ("S 1"."T 3" r1 FULL JOIN "S 1"."T 4" r2 ON (((r1.c1 = r2.c1)))) WHERE (((r1.c1 < 20) OR ((r1.c1 IS NULL) AND (r2.c1 < 5)))) GROUP BY 2
(7 rows)
Relations: Aggregate on ((public.ft4 t1) FULL JOIN (public.ft5 t2))
Remote SQL: SELECT array_agg(DISTINCT (r1.c1 % 5)), (r2.c1 % 3) FROM ("S 1"."T 3" r1 FULL JOIN "S 1"."T 4" r2 ON (((r1.c1 = r2.c1)))) WHERE (((r1.c1 < 20) OR ((r1.c1 IS NULL) AND (r2.c1 < 5)))) GROUP BY 2 ORDER BY array_agg(DISTINCT (r1.c1 % 5)) ASC NULLS LAST
(4 rows)
select array_agg(distinct (t1.c1)%5) from ft4 t1 full join ft5 t2 on (t1.c1 = t2.c1) where t1.c1 < 20 or (t1.c1 is null and t2.c1 < 5) group by (t2.c1)%3 order by 1;
array_agg
@ -2890,16 +2867,13 @@ select array_agg(distinct (t1.c1)%5) from ft4 t1 full join ft5 t2 on (t1.c1 = t2
-- DISTINCT combined with ORDER BY within aggregate
explain (verbose, costs off)
select array_agg(distinct (t1.c1)%5 order by (t1.c1)%5) from ft4 t1 full join ft5 t2 on (t1.c1 = t2.c1) where t1.c1 < 20 or (t1.c1 is null and t2.c1 < 5) group by (t2.c1)%3 order by 1;
QUERY PLAN
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Sort
QUERY PLAN
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Foreign Scan
Output: (array_agg(DISTINCT (t1.c1 % 5) ORDER BY (t1.c1 % 5))), ((t2.c1 % 3))
Sort Key: (array_agg(DISTINCT (t1.c1 % 5) ORDER BY (t1.c1 % 5)))
-> Foreign Scan
Output: (array_agg(DISTINCT (t1.c1 % 5) ORDER BY (t1.c1 % 5))), ((t2.c1 % 3))
Relations: Aggregate on ((public.ft4 t1) FULL JOIN (public.ft5 t2))
Remote SQL: SELECT array_agg(DISTINCT (r1.c1 % 5) ORDER BY ((r1.c1 % 5)) ASC NULLS LAST), (r2.c1 % 3) FROM ("S 1"."T 3" r1 FULL JOIN "S 1"."T 4" r2 ON (((r1.c1 = r2.c1)))) WHERE (((r1.c1 < 20) OR ((r1.c1 IS NULL) AND (r2.c1 < 5)))) GROUP BY 2
(7 rows)
Relations: Aggregate on ((public.ft4 t1) FULL JOIN (public.ft5 t2))
Remote SQL: SELECT array_agg(DISTINCT (r1.c1 % 5) ORDER BY ((r1.c1 % 5)) ASC NULLS LAST), (r2.c1 % 3) FROM ("S 1"."T 3" r1 FULL JOIN "S 1"."T 4" r2 ON (((r1.c1 = r2.c1)))) WHERE (((r1.c1 < 20) OR ((r1.c1 IS NULL) AND (r2.c1 < 5)))) GROUP BY 2 ORDER BY array_agg(DISTINCT (r1.c1 % 5) ORDER BY ((r1.c1 % 5)) ASC NULLS LAST) ASC NULLS LAST
(4 rows)
select array_agg(distinct (t1.c1)%5 order by (t1.c1)%5) from ft4 t1 full join ft5 t2 on (t1.c1 = t2.c1) where t1.c1 < 20 or (t1.c1 is null and t2.c1 < 5) group by (t2.c1)%3 order by 1;
array_agg
@ -2910,16 +2884,13 @@ select array_agg(distinct (t1.c1)%5 order by (t1.c1)%5) from ft4 t1 full join ft
explain (verbose, costs off)
select array_agg(distinct (t1.c1)%5 order by (t1.c1)%5 desc nulls last) from ft4 t1 full join ft5 t2 on (t1.c1 = t2.c1) where t1.c1 < 20 or (t1.c1 is null and t2.c1 < 5) group by (t2.c1)%3 order by 1;
QUERY PLAN
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Sort
QUERY PLAN
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Foreign Scan
Output: (array_agg(DISTINCT (t1.c1 % 5) ORDER BY (t1.c1 % 5) DESC NULLS LAST)), ((t2.c1 % 3))
Sort Key: (array_agg(DISTINCT (t1.c1 % 5) ORDER BY (t1.c1 % 5) DESC NULLS LAST))
-> Foreign Scan
Output: (array_agg(DISTINCT (t1.c1 % 5) ORDER BY (t1.c1 % 5) DESC NULLS LAST)), ((t2.c1 % 3))
Relations: Aggregate on ((public.ft4 t1) FULL JOIN (public.ft5 t2))
Remote SQL: SELECT array_agg(DISTINCT (r1.c1 % 5) ORDER BY ((r1.c1 % 5)) DESC NULLS LAST), (r2.c1 % 3) FROM ("S 1"."T 3" r1 FULL JOIN "S 1"."T 4" r2 ON (((r1.c1 = r2.c1)))) WHERE (((r1.c1 < 20) OR ((r1.c1 IS NULL) AND (r2.c1 < 5)))) GROUP BY 2
(7 rows)
Relations: Aggregate on ((public.ft4 t1) FULL JOIN (public.ft5 t2))
Remote SQL: SELECT array_agg(DISTINCT (r1.c1 % 5) ORDER BY ((r1.c1 % 5)) DESC NULLS LAST), (r2.c1 % 3) FROM ("S 1"."T 3" r1 FULL JOIN "S 1"."T 4" r2 ON (((r1.c1 = r2.c1)))) WHERE (((r1.c1 < 20) OR ((r1.c1 IS NULL) AND (r2.c1 < 5)))) GROUP BY 2 ORDER BY array_agg(DISTINCT (r1.c1 % 5) ORDER BY ((r1.c1 % 5)) DESC NULLS LAST) ASC NULLS LAST
(4 rows)
select array_agg(distinct (t1.c1)%5 order by (t1.c1)%5 desc nulls last) from ft4 t1 full join ft5 t2 on (t1.c1 = t2.c1) where t1.c1 < 20 or (t1.c1 is null and t2.c1 < 5) group by (t2.c1)%3 order by 1;
array_agg
@ -2931,16 +2902,13 @@ select array_agg(distinct (t1.c1)%5 order by (t1.c1)%5 desc nulls last) from ft4
-- FILTER within aggregate
explain (verbose, costs off)
select sum(c1) filter (where c1 < 100 and c2 > 5) from ft1 group by c2 order by 1 nulls last;
QUERY PLAN
-------------------------------------------------------------------------------------------------------------------
Sort
QUERY PLAN
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Foreign Scan
Output: (sum(c1) FILTER (WHERE ((c1 < 100) AND (c2 > 5)))), c2
Sort Key: (sum(ft1.c1) FILTER (WHERE ((ft1.c1 < 100) AND (ft1.c2 > 5))))
-> Foreign Scan
Output: (sum(c1) FILTER (WHERE ((c1 < 100) AND (c2 > 5)))), c2
Relations: Aggregate on (public.ft1)
Remote SQL: SELECT sum("C 1") FILTER (WHERE (("C 1" < 100) AND (c2 > 5))), c2 FROM "S 1"."T 1" GROUP BY 2
(7 rows)
Relations: Aggregate on (public.ft1)
Remote SQL: SELECT sum("C 1") FILTER (WHERE (("C 1" < 100) AND (c2 > 5))), c2 FROM "S 1"."T 1" GROUP BY 2 ORDER BY sum("C 1") FILTER (WHERE (("C 1" < 100) AND (c2 > 5))) ASC NULLS LAST
(4 rows)
select sum(c1) filter (where c1 < 100 and c2 > 5) from ft1 group by c2 order by 1 nulls last;
sum
@ -3339,16 +3307,13 @@ select count(*), x.b from ft1, (select c2 a, sum(c1) b from ft1 group by c2) x w
-- FULL join with IS NULL check in HAVING
explain (verbose, costs off)
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;
QUERY PLAN
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Sort
QUERY PLAN
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Foreign Scan
Output: (avg(t1.c1)), (sum(t2.c1)), t2.c1
Sort Key: (avg(t1.c1)), (sum(t2.c1))
-> Foreign Scan
Output: (avg(t1.c1)), (sum(t2.c1)), t2.c1
Relations: Aggregate on ((public.ft4 t1) FULL JOIN (public.ft5 t2))
Remote SQL: SELECT avg(r1.c1), sum(r2.c1), r2.c1 FROM ("S 1"."T 3" r1 FULL JOIN "S 1"."T 4" r2 ON (((r1.c1 = r2.c1)))) GROUP BY 3 HAVING ((((avg(r1.c1) IS NULL) AND (sum(r2.c1) < 10)) OR (sum(r2.c1) IS NULL)))
(7 rows)
Relations: Aggregate on ((public.ft4 t1) FULL JOIN (public.ft5 t2))
Remote SQL: SELECT avg(r1.c1), sum(r2.c1), r2.c1 FROM ("S 1"."T 3" r1 FULL JOIN "S 1"."T 4" r2 ON (((r1.c1 = r2.c1)))) GROUP BY 3 HAVING ((((avg(r1.c1) IS NULL) AND (sum(r2.c1) < 10)) OR (sum(r2.c1) IS NULL))) ORDER BY avg(r1.c1) ASC NULLS LAST, sum(r2.c1) ASC NULLS LAST
(4 rows)
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;
avg | sum

388
contrib/postgres_fdw/postgres_fdw.c
Unescape View File

@ -246,6 +246,25 @@ typedef struct PgFdwAnalyzeState
MemoryContext temp_cxt; /* context for per-tuple temporary data */
} PgFdwAnalyzeState;
/*
* This enum describes what's kept in the fdw_private list for a ForeignPath.
* We store:
*
* 1) Boolean flag showing if the remote query has the final sort
*/
enum FdwPathPrivateIndex
{
/* has-final-sort flag (as an integer Value node) */
FdwPathPrivateHasFinalSort
};
/* Struct for extra information passed to estimate_path_cost_size() */
typedef struct
{
PathTarget *target;
bool has_final_sort;
} PgFdwPathExtraData;
/*
* Identify the attribute where data conversion fails.
*/
@ -368,6 +387,7 @@ static void estimate_path_cost_size(PlannerInfo *root,
RelOptInfo *foreignrel,
List *param_join_conds,
List *pathkeys,
PgFdwPathExtraData *fpextra,
double *p_rows, int *p_width,
Cost *p_startup_cost, Cost *p_total_cost);
static void get_remote_estimate(const char *sql,
@ -376,6 +396,12 @@ static void get_remote_estimate(const char *sql,
int *width,
Cost *startup_cost,
Cost *total_cost);
static void adjust_foreign_grouping_path_cost(PlannerInfo *root,
List *pathkeys,
double retrieved_rows,
double width,
Cost *p_startup_cost,
Cost *p_run_cost);
static bool ec_member_matches_foreign(PlannerInfo *root, RelOptInfo *rel,
EquivalenceClass *ec, EquivalenceMember *em,
void *arg);
@ -452,6 +478,9 @@ static void add_foreign_grouping_paths(PlannerInfo *root,
RelOptInfo *input_rel,
RelOptInfo *grouped_rel,
GroupPathExtraData *extra);
static void add_foreign_ordered_paths(PlannerInfo *root,
RelOptInfo *input_rel,
RelOptInfo *ordered_rel);
static void apply_server_options(PgFdwRelationInfo *fpinfo);
static void apply_table_options(PgFdwRelationInfo *fpinfo);
static void merge_fdw_options(PgFdwRelationInfo *fpinfo,
@ -637,7 +666,7 @@ postgresGetForeignRelSize(PlannerInfo *root,
* values in fpinfo so we don't need to do it again to generate the
* basic foreign path.
*/
estimate_path_cost_size(root, baserel, NIL, NIL,
estimate_path_cost_size(root, baserel, NIL, NIL, NULL,
&fpinfo->rows, &fpinfo->width,
&fpinfo->startup_cost, &fpinfo->total_cost);
@ -668,7 +697,7 @@ postgresGetForeignRelSize(PlannerInfo *root,
set_baserel_size_estimates(root, baserel);
/* Fill in basically-bogus cost estimates for use later. */
estimate_path_cost_size(root, baserel, NIL, NIL,
estimate_path_cost_size(root, baserel, NIL, NIL, NULL,
&fpinfo->rows, &fpinfo->width,
&fpinfo->startup_cost, &fpinfo->total_cost);
}
@ -827,6 +856,7 @@ get_useful_pathkeys_for_relation(PlannerInfo *root, RelOptInfo *rel)
* Pushing the query_pathkeys to the remote server is always worth
* considering, because it might let us avoid a local sort.
*/
fpinfo->qp_is_pushdown_safe = false;
if (root->query_pathkeys)
{
bool query_pathkeys_ok = true;
@ -857,7 +887,10 @@ get_useful_pathkeys_for_relation(PlannerInfo *root, RelOptInfo *rel)
}
if (query_pathkeys_ok)
{
useful_pathkeys_list = list_make1(list_copy(root->query_pathkeys));
fpinfo->qp_is_pushdown_safe = true;
}
}
/*
@ -1102,7 +1135,7 @@ postgresGetForeignPaths(PlannerInfo *root,
/* Get a cost estimate from the remote */
estimate_path_cost_size(root, baserel,
param_info->ppi_clauses, NIL,
param_info->ppi_clauses, NIL, NULL,
&rows, &width,
&startup_cost, &total_cost);
@ -1149,8 +1182,16 @@ postgresGetForeignPlan(PlannerInfo *root,
List *fdw_recheck_quals = NIL;
List *retrieved_attrs;
StringInfoData sql;
bool has_final_sort = false;
ListCell *lc;
/*
* Get FDW private data created by postgresGetForeignUpperPaths(), if any.
*/
if (best_path->fdw_private)
has_final_sort = intVal(list_nth(best_path->fdw_private,
FdwPathPrivateHasFinalSort));
if (IS_SIMPLE_REL(foreignrel))
{
/*
@ -1299,7 +1340,8 @@ postgresGetForeignPlan(PlannerInfo *root,
initStringInfo(&sql);
deparseSelectStmtForRel(&sql, root, foreignrel, fdw_scan_tlist,
remote_exprs, best_path->path.pathkeys,
false, &retrieved_attrs, &params_list);
has_final_sort, false,
&retrieved_attrs, &params_list);
/* Remember remote_exprs for possible use by postgresPlanDirectModify */
fpinfo->final_remote_exprs = remote_exprs;
@ -2483,6 +2525,8 @@ postgresExplainDirectModify(ForeignScanState *node, ExplainState *es)
*
* param_join_conds are the parameterization clauses with outer relations.
* pathkeys specify the expected sort order if any for given path being costed.
* fpextra specifies additional post-scan/join-processing steps such as the
* final sort.
*
* The function returns the cost and size estimates in p_row, p_width,
* p_startup_cost and p_total_cost variables.
@ -2492,6 +2536,7 @@ estimate_path_cost_size(PlannerInfo *root,
RelOptInfo *foreignrel,
List *param_join_conds,
List *pathkeys,
PgFdwPathExtraData *fpextra,
double *p_rows, int *p_width,
Cost *p_startup_cost, Cost *p_total_cost)
{
@ -2556,8 +2601,9 @@ estimate_path_cost_size(PlannerInfo *root,
initStringInfo(&sql);
appendStringInfoString(&sql, "EXPLAIN ");
deparseSelectStmtForRel(&sql, root, foreignrel, fdw_scan_tlist,
remote_conds, pathkeys, false,
&retrieved_attrs, NULL);
remote_conds, pathkeys,
fpextra ? fpextra->has_final_sort : false,
false, &retrieved_attrs, NULL);
/* Get the remote estimate */
conn = GetConnection(fpinfo->user, false);
@ -2625,9 +2671,9 @@ estimate_path_cost_size(PlannerInfo *root,
/*
* We will come here again and again with different set of pathkeys
* that caller wants to cost. We don't need to calculate the cost of
* bare scan each time. Instead, use the costs if we have cached them
* already.
* that caller wants to cost. We don't need to calculate the costs of
* the underlying scan, join, or grouping each time. Instead, use the
* costs if we have cached them already.
*/
if (fpinfo->rel_startup_cost >= 0 && fpinfo->rel_total_cost >= 0)
{
@ -2845,23 +2891,52 @@ estimate_path_cost_size(PlannerInfo *root,
*/
if (pathkeys != NIL)
{
startup_cost *= DEFAULT_FDW_SORT_MULTIPLIER;
run_cost *= DEFAULT_FDW_SORT_MULTIPLIER;
if (IS_UPPER_REL(foreignrel))
{
Assert(foreignrel->reloptkind == RELOPT_UPPER_REL &&
fpinfo->stage == UPPERREL_GROUP_AGG);
adjust_foreign_grouping_path_cost(root, pathkeys,
retrieved_rows, width,
&startup_cost, &run_cost);
}
else
{
startup_cost *= DEFAULT_FDW_SORT_MULTIPLIER;
run_cost *= DEFAULT_FDW_SORT_MULTIPLIER;
}
}
total_cost = startup_cost + run_cost;
}
/*
* Cache the costs for scans without any pathkeys or parameterization
* before adding the costs for transferring data from the foreign server.
* These costs are useful for costing the join between this relation and
* another foreign relation or to calculate the costs of paths with
* pathkeys for this relation, when the costs can not be obtained from the
* foreign server. This function will be called at least once for every
* foreign relation without pathkeys and parameterization.
* If this includes the final sort step, the given target, which will be
* applied to the resulting path, might have different expressions from
* the foreignrel's reltarget (see make_sort_input_target()); adjust tlist
* eval costs.
*/
if (pathkeys == NIL && param_join_conds == NIL)
if (fpextra && fpextra->target != foreignrel->reltarget)
{
QualCost oldcost = foreignrel->reltarget->cost;
QualCost newcost = fpextra->target->cost;
startup_cost += newcost.startup - oldcost.startup;
total_cost += newcost.startup - oldcost.startup;
total_cost += (newcost.per_tuple - oldcost.per_tuple) * rows;
}
/*
* Cache the costs for scans, joins, or groupings without any
* parameterization, pathkeys, or additional post-scan/join-processing
* steps, before adding the costs for transferring data from the foreign
* server. These costs are useful for costing remote joins involving this
* relation or costing other remote operations for this relation such as
* remote sorts, when the costs can not be obtained from the foreign
* server. This function will be called at least once for every foreign
* relation without any parameterization, pathkeys, or additional
* post-scan/join-processing steps.
*/
if (pathkeys == NIL && param_join_conds == NIL && fpextra == NULL)
{
fpinfo->rel_startup_cost = startup_cost;
fpinfo->rel_total_cost = total_cost;
@ -2936,6 +3011,58 @@ get_remote_estimate(const char *sql, PGconn *conn,
PG_END_TRY();
}
/*
* Adjust the cost estimates of a foreign grouping path to include the cost of
* generating properly-sorted output.
*/
static void
adjust_foreign_grouping_path_cost(PlannerInfo *root,
List *pathkeys,
double retrieved_rows,
double width,
Cost *p_startup_cost,
Cost *p_run_cost)
{
/*
* If the GROUP BY clause isn't sort-able, the plan chosen by the remote
* side is unlikely to generate properly-sorted output, so it would need
* an explicit sort; adjust the given costs with cost_sort(). Likewise,
* if the GROUP BY clause is sort-able but isn't a superset of the given
* pathkeys, adjust the costs with that function. Otherwise, adjust the
* costs by applying the same heuristic as for the scan or join case.
*/
if (!grouping_is_sortable(root->parse->groupClause) ||
!pathkeys_contained_in(pathkeys, root->group_pathkeys))
{
Path sort_path; /* dummy for result of cost_sort */
cost_sort(&sort_path,
root,
pathkeys,
*p_startup_cost + *p_run_cost,
retrieved_rows,
width,
0.0,
work_mem,
-1.0);
*p_startup_cost = sort_path.startup_cost;
*p_run_cost = sort_path.total_cost - sort_path.startup_cost;
}
else
{
/*
* The default extra cost seems too large for foreign-grouping cases;
* add 1/4th of that default.
*/
double sort_multiplier = 1.0 + (DEFAULT_FDW_SORT_MULTIPLIER
- 1.0) * 0.25;
*p_startup_cost *= sort_multiplier;
*p_run_cost *= sort_multiplier;
}
}
/*
* Detect whether we want to process an EquivalenceClass member.
*
@ -4935,7 +5062,7 @@ add_paths_with_pathkeys_for_rel(PlannerInfo *root, RelOptInfo *rel,
List *useful_pathkeys = lfirst(lc);
Path *sorted_epq_path;
estimate_path_cost_size(root, rel, NIL, useful_pathkeys,
estimate_path_cost_size(root, rel, NIL, useful_pathkeys, NULL,
&rows, &width, &startup_cost, &total_cost);
/*
@ -5186,8 +5313,8 @@ postgresGetForeignJoinPaths(PlannerInfo *root,
extra->sjinfo);
/* Estimate costs for bare join relation */
estimate_path_cost_size(root, joinrel, NIL, NIL, &rows,
&width, &startup_cost, &total_cost);
estimate_path_cost_size(root, joinrel, NIL, NIL, NULL,
&rows, &width, &startup_cost, &total_cost);
/* Now update this information in the joinrel */
joinrel->rows = rows;
joinrel->reltarget->width = width;
@ -5437,8 +5564,6 @@ foreign_grouping_ok(PlannerInfo *root, RelOptInfo *grouped_rel,
* postgresGetForeignUpperPaths
* Add paths for post-join operations like aggregation, grouping etc. if
* corresponding operations are safe to push down.
*
* Right now, we only support aggregate, grouping and having clause pushdown.
*/
static void
postgresGetForeignUpperPaths(PlannerInfo *root, UpperRelationKind stage,
@ -5456,15 +5581,29 @@ postgresGetForeignUpperPaths(PlannerInfo *root, UpperRelationKind stage,
return;
/* Ignore stages we don't support; and skip any duplicate calls. */
if (stage != UPPERREL_GROUP_AGG || output_rel->fdw_private)
if ((stage != UPPERREL_GROUP_AGG &&
stage != UPPERREL_ORDERED) ||
output_rel->fdw_private)
return;
fpinfo = (PgFdwRelationInfo *) palloc0(sizeof(PgFdwRelationInfo));
fpinfo->pushdown_safe = false;
fpinfo->stage = stage;
output_rel->fdw_private = fpinfo;
add_foreign_grouping_paths(root, input_rel, output_rel,
(GroupPathExtraData *) extra);
switch (stage)
{
case UPPERREL_GROUP_AGG:
add_foreign_grouping_paths(root, input_rel, output_rel,
(GroupPathExtraData *) extra);
break;
case UPPERREL_ORDERED:
add_foreign_ordered_paths(root, input_rel, output_rel);
break;
default:
elog(ERROR, "unexpected upper relation: %d", (int) stage);
break;
}
}
/*
@ -5534,8 +5673,8 @@ add_foreign_grouping_paths(PlannerInfo *root, RelOptInfo *input_rel,
cost_qual_eval(&fpinfo->local_conds_cost, fpinfo->local_conds, root);
/* Estimate the cost of push down */
estimate_path_cost_size(root, grouped_rel, NIL, NIL, &rows,
&width, &startup_cost, &total_cost);
estimate_path_cost_size(root, grouped_rel, NIL, NIL, NULL,
&rows, &width, &startup_cost, &total_cost);
/* Now update this information in the fpinfo */
fpinfo->rows = rows;
@ -5543,6 +5682,8 @@ add_foreign_grouping_paths(PlannerInfo *root, RelOptInfo *input_rel,
fpinfo->startup_cost = startup_cost;
fpinfo->total_cost = total_cost;
grouped_rel->rows = fpinfo->rows;
/* Create and add foreign path to the grouping relation. */
grouppath = create_foreign_upper_path(root,
grouped_rel,
@ -5558,6 +5699,133 @@ add_foreign_grouping_paths(PlannerInfo *root, RelOptInfo *input_rel,
add_path(grouped_rel, (Path *) grouppath);
}
/*
* add_foreign_ordered_paths
* Add foreign paths for performing the final sort remotely.
*
* Given input_rel contains the source-data Paths. The paths are added to the
* given ordered_rel.
*/
static void
add_foreign_ordered_paths(PlannerInfo *root, RelOptInfo *input_rel,
RelOptInfo *ordered_rel)
{
Query *parse = root->parse;
PgFdwRelationInfo *ifpinfo = input_rel->fdw_private;
PgFdwRelationInfo *fpinfo = ordered_rel->fdw_private;
PgFdwPathExtraData *fpextra;
double rows;
int width;
Cost startup_cost;
Cost total_cost;
List *fdw_private;
ForeignPath *ordered_path;
ListCell *lc;
/* Shouldn't get here unless the query has ORDER BY */
Assert(parse->sortClause);
/* We don't support cases where there are any SRFs in the targetlist */
if (parse->hasTargetSRFs)
return;
/* Save the input_rel as outerrel in fpinfo */
fpinfo->outerrel = input_rel;
/*
* Copy foreign table, foreign server, user mapping, FDW options etc.
* details from the input relation's fpinfo.
*/
fpinfo->table = ifpinfo->table;
fpinfo->server = ifpinfo->server;
fpinfo->user = ifpinfo->user;
merge_fdw_options(fpinfo, ifpinfo, NULL);
/*
* If the input_rel is a base or join relation, we would already have
* considered pushing down the final sort to the remote server when
* creating pre-sorted foreign paths for that relation, because the
* query_pathkeys is set to the root->sort_pathkeys in that case (see
* standard_qp_callback()).
*/
if (input_rel->reloptkind == RELOPT_BASEREL ||
input_rel->reloptkind == RELOPT_JOINREL)
{
Assert(root->query_pathkeys == root->sort_pathkeys);
/* Safe to push down if the query_pathkeys is safe to push down */
fpinfo->pushdown_safe = ifpinfo->qp_is_pushdown_safe;
return;
}
/* The input_rel should be a grouping relation */
Assert(input_rel->reloptkind == RELOPT_UPPER_REL &&
ifpinfo->stage == UPPERREL_GROUP_AGG);
/*
* We try to create a path below by extending a simple foreign path for
* the underlying grouping relation to perform the final sort remotely,
* which is stored into the fdw_private list of the resulting path.
*/
/* Assess if it is safe to push down the final sort */
foreach(lc, root->sort_pathkeys)
{
PathKey *pathkey = (PathKey *) lfirst(lc);
EquivalenceClass *pathkey_ec = pathkey->pk_eclass;
Expr *sort_expr;
/*
* is_foreign_expr would detect volatile expressions as well, but
* checking ec_has_volatile here saves some cycles.
*/
if (pathkey_ec->ec_has_volatile)
return;
/* Get the sort expression for the pathkey_ec */
sort_expr = find_em_expr_for_input_target(root,
pathkey_ec,
input_rel->reltarget);
/* If it's unsafe to remote, we cannot push down the final sort */
if (!is_foreign_expr(root, input_rel, sort_expr))
return;
}
/* Safe to push down */
fpinfo->pushdown_safe = true;
/* Construct PgFdwPathExtraData */
fpextra = (PgFdwPathExtraData *) palloc0(sizeof(PgFdwPathExtraData));
fpextra->target = root->upper_targets[UPPERREL_ORDERED];
fpextra->has_final_sort = true;
/* Estimate the costs of performing the final sort remotely */
estimate_path_cost_size(root, input_rel, NIL, root->sort_pathkeys, fpextra,
&rows, &width, &startup_cost, &total_cost);
/*
* Build the fdw_private list that will be used by postgresGetForeignPlan.
* Items in the list must match order in enum FdwPathPrivateIndex.
*/
fdw_private = list_make1(makeInteger(true));
/* Create foreign ordering path */
ordered_path = create_foreign_upper_path(root,
input_rel,
root->upper_targets[UPPERREL_ORDERED],
rows,
startup_cost,
total_cost,
root->sort_pathkeys,
NULL, /* no extra plan */
fdw_private);
/* and add it to the ordered_rel */
add_path(ordered_rel, (Path *) ordered_path);
}
/*
* Create a tuple from the specified row of the PGresult.
*
@ -5808,3 +6076,65 @@ find_em_expr_for_rel(EquivalenceClass *ec, RelOptInfo *rel)
/* We didn't find any suitable equivalence class expression */
return NULL;
}
/*
* Find an equivalence class member expression to be computed as a sort column
* in the given target.
*/
Expr *
find_em_expr_for_input_target(PlannerInfo *root,
EquivalenceClass *ec,
PathTarget *target)
{
ListCell *lc1;
int i;
i = 0;
foreach(lc1, target->exprs)
{
Expr *expr = (Expr *) lfirst(lc1);
Index sgref = get_pathtarget_sortgroupref(target, i);
ListCell *lc2;
/* Ignore non-sort expressions */
if (sgref == 0 ||
get_sortgroupref_clause_noerr(sgref,
root->parse->sortClause) == NULL)
{
i++;
continue;
}
/* We ignore binary-compatible relabeling on both ends */
while (expr && IsA(expr, RelabelType))
expr = ((RelabelType *) expr)->arg;
/* Locate an EquivalenceClass member matching this expr, if any */
foreach(lc2, ec->ec_members)
{
EquivalenceMember *em = (EquivalenceMember *) lfirst(lc2);
Expr *em_expr;
/* Don't match constants */
if (em->em_is_const)
continue;
/* Ignore child members */
if (em->em_is_child)
continue;
/* Match if same expression (after stripping relabel) */
em_expr = em->em_expr;
while (em_expr && IsA(em_expr, RelabelType))
em_expr = ((RelabelType *) em_expr)->arg;
if (equal(em_expr, expr))
return em->em_expr;
}
i++;
}
elog(ERROR, "could not find pathkey item to sort");
return NULL; /* keep compiler quiet */
}

12
contrib/postgres_fdw/postgres_fdw.h
Unescape View File

@ -49,6 +49,9 @@ typedef struct PgFdwRelationInfo
/* Bitmap of attr numbers we need to fetch from the remote server. */
Bitmapset *attrs_used;
/* True means that the query_pathkeys is safe to push down */
bool qp_is_pushdown_safe;
/* Cost and selectivity of local_conds. */
QualCost local_conds_cost;
Selectivity local_conds_sel;
@ -92,6 +95,9 @@ typedef struct PgFdwRelationInfo
/* joinclauses contains only JOIN/ON conditions for an outer join */
List *joinclauses; /* List of RestrictInfo */
/* Upper relation information */
UpperRelationKind stage;
/* Grouping information */
List *grouped_tlist;
@ -175,10 +181,14 @@ extern void deparseAnalyzeSql(StringInfo buf, Relation rel,
List **retrieved_attrs);
extern void deparseStringLiteral(StringInfo buf, const char *val);
extern Expr *find_em_expr_for_rel(EquivalenceClass *ec, RelOptInfo *rel);
extern Expr *find_em_expr_for_input_target(PlannerInfo *root,
EquivalenceClass *ec,
PathTarget *target);
extern List *build_tlist_to_deparse(RelOptInfo *foreignrel);
extern void deparseSelectStmtForRel(StringInfo buf, PlannerInfo *root,
RelOptInfo *foreignrel, List *tlist,
List *remote_conds, List *pathkeys, bool is_subquery,
List *remote_conds, List *pathkeys,
bool has_final_sort, bool is_subquery,
List **retrieved_attrs, List **params_list);
extern const char *get_jointype_name(JoinType jointype);

Write Preview
Loading…
Cancel
Save