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Relax reference table restrictions in subquery union pushdowns 

We used to error out if there is a reference table
in the query participating a union. This has caused
pushdownable queries to be evaluated in coordinator.

Now we let reference tables inside union queries as long
as there is a distributed table in from clause.

Existing join checks (reference table on the outer part)
sufficient enought that we do not need check the join relation
of reference tables.
pull/2590/head
Murat Tuncer 2019-01-15 11:13:30 +03:00
parent 501eaebe77
commit b36b59dd4f
3 changed files with 351 additions and 90 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

86
src/backend/distributed/planner/query_pushdown_planning.c
View File

@ -65,6 +65,7 @@ static bool IsNodeQuery(Node *node);
static bool IsOuterJoinExpr(Node *node);
static bool WindowPartitionOnDistributionColumn(Query *query);
static DeferredErrorMessage * DeferErrorIfFromClauseRecurs(Query *queryTree);
static RecurringTuplesType FromClauseRecurringTupleType(Query *queryTree);
static DeferredErrorMessage * DeferredErrorIfUnsupportedRecurringTuplesJoin(
PlannerRestrictionContext *plannerRestrictionContext);
static DeferredErrorMessage * DeferErrorIfUnsupportedTableCombination(Query *queryTree);
@ -572,30 +573,7 @@ DeferErrorIfFromClauseRecurs(Query *queryTree)
return NULL;
}
if (FindNodeCheckInRangeTableList(queryTree->rtable, IsDistributedTableRTE))
{
/*
* There is a distributed table somewhere in the FROM clause.
*
* In the typical case this means that the query does not recur,
* but there are two exceptions:
*
* - outer joins such as reference_table LEFT JOIN distributed_table
* - FROM reference_table WHERE .. (SELECT .. FROM distributed_table) ..
*
* However, we check all subqueries and joins separately, so we would
* find such conditions in other calls.
*/
return NULL;
}
/*
* Try to figure out which type of recurring tuples we have to produce a
* relevant error message. If there are several we'll pick the first one.
*/
IsRecurringRangeTable(queryTree->rtable, &recurType);
recurType = FromClauseRecurringTupleType(queryTree);
if (recurType == RECURRING_TUPLES_REFERENCE_TABLE)
{
return DeferredError(ERRCODE_FEATURE_NOT_SUPPORTED,
@ -644,6 +622,50 @@ DeferErrorIfFromClauseRecurs(Query *queryTree)
}
/*
* FromClauseRecurringTupleType returns tuple recurrence information
* in query result based on range table entries in from clause.
*
* Returned information is used to prepare appropriate deferred error
* message for subquery pushdown checks.
*/
static RecurringTuplesType
FromClauseRecurringTupleType(Query *queryTree)
{
RecurringTuplesType recurType = RECURRING_TUPLES_INVALID;
if (queryTree->rtable == NIL)
{
return RECURRING_TUPLES_EMPTY_JOIN_TREE;
}
if (FindNodeCheckInRangeTableList(queryTree->rtable, IsDistributedTableRTE))
{
/*
* There is a distributed table somewhere in the FROM clause.
*
* In the typical case this means that the query does not recur,
* but there are two exceptions:
*
* - outer joins such as reference_table LEFT JOIN distributed_table
* - FROM reference_table WHERE .. (SELECT .. FROM distributed_table) ..
*
* However, we check all subqueries and joins separately, so we would
* find such conditions in other calls.
*/
return RECURRING_TUPLES_INVALID;
}
/*
* Try to figure out which type of recurring tuples we have to produce a
* relevant error message. If there are several we'll pick the first one.
*/
IsRecurringRangeTable(queryTree->rtable, &recurType);
return recurType;
}
/*
* DeferredErrorIfUnsupportedRecurringTuplesJoin returns true if there exists a outer join
* between reference table and distributed tables which does not follow
@ -1062,11 +1084,11 @@ DeferErrorIfUnsupportedUnionQuery(Query *subqueryTree)
if (IsA(leftArg, RangeTblRef))
{
Node *leftArgSubquery = NULL;
Query *leftArgSubquery = NULL;
leftArgRTI = ((RangeTblRef *) leftArg)->rtindex;
leftArgSubquery = (Node *) rt_fetch(leftArgRTI,
subqueryTree->rtable)->subquery;
if (HasRecurringTuples(leftArgSubquery, &recurType))
leftArgSubquery = rt_fetch(leftArgRTI, subqueryTree->rtable)->subquery;
recurType = FromClauseRecurringTupleType(leftArgSubquery);
if (recurType != RECURRING_TUPLES_INVALID)
{
break;
}
@ -1074,11 +1096,11 @@ DeferErrorIfUnsupportedUnionQuery(Query *subqueryTree)
if (IsA(rightArg, RangeTblRef))
{
Node *rightArgSubquery = NULL;
Query *rightArgSubquery = NULL;
rightArgRTI = ((RangeTblRef *) rightArg)->rtindex;
rightArgSubquery = (Node *) rt_fetch(rightArgRTI,
subqueryTree->rtable)->subquery;
if (HasRecurringTuples(rightArgSubquery, &recurType))
rightArgSubquery = rt_fetch(rightArgRTI, subqueryTree->rtable)->subquery;
recurType = FromClauseRecurringTupleType(rightArgSubquery);
if (recurType != RECURRING_TUPLES_INVALID)
{
break;
}

217
src/test/regress/expected/multi_subquery_complex_reference_clause.out
View File

@ -150,15 +150,22 @@ WHERE subquery_1.user_id = subquery_2.user_id ;
4
(1 row)
-- Should be able to push down since reference tables are inner joined
-- with hash distributed tables, the results of those joins are the parts of
-- an outer join
SELECT subquery_2.id FROM
(SELECT tt1.user_id, random() FROM user_buy_test_table AS tt1 JOIN users_return_test_table as tt2
ON tt1.user_id = tt2.user_id) subquery_1
RIGHT JOIN
(SELECT tt1.user_id, ref.id, random() FROM user_buy_test_table as tt1 JOIN users_ref_test_table as ref
ON tt1.user_id = ref.id) subquery_2 ON subquery_1.user_id = subquery_2.user_id ORDER BY 1 DESC LIMIT 5;
-- Should be able to push down since reference tables are inner joined
-- with hash distributed tables, the results of those joins are the parts of
-- an outer join
SELECT subquery_2.id
FROM
(SELECT tt1.user_id, random()
FROM user_buy_test_table AS tt1
JOIN users_return_test_table as tt2
ON tt1.user_id = tt2.user_id) subquery_1
RIGHT JOIN
(SELECT tt1.user_id, ref.id, random()
FROM user_buy_test_table as tt1
JOIN users_ref_test_table as ref
ON tt1.user_id = ref.id) subquery_2
ON subquery_1.user_id = subquery_2.user_id
ORDER BY 1 DESC LIMIT 5;
id
----
3
@ -166,14 +173,23 @@ SELECT subquery_2.id FROM
1
(3 rows)
-- the same query as the above, but this Citus fails to pushdown the query
-- since the outer part of the right join doesn't include any joins
SELECT * FROM
(SELECT tt1.user_id, random() FROM user_buy_test_table AS tt1 JOIN users_return_test_table as tt2
ON tt1.user_id = tt2.user_id) subquery_1
RIGHT JOIN
(SELECT *, random() FROM (SELECT tt1.user_id, random() FROM user_buy_test_table as tt1 JOIN users_ref_test_table as ref
ON tt1.user_id = ref.id) subquery_2_inner) subquery_2 ON subquery_1.user_id = subquery_2.user_id;
-- almost the same query as the above, but reference table join wrapped with
-- another subquery
SELECT subquery_1.user_id
FROM
(SELECT tt1.user_id, random()
FROM user_buy_test_table AS tt1
JOIN users_return_test_table as tt2
ON tt1.user_id = tt2.user_id) subquery_1
RIGHT JOIN
(SELECT *, random()
FROM
(SELECT tt1.user_id, random()
FROM user_buy_test_table as tt1
JOIN users_ref_test_table as ref
ON tt1.user_id = ref.id) subquery_2_inner) subquery_2
ON subquery_1.user_id = subquery_2.user_id
ORDER BY 1;
ERROR: cannot pushdown the subquery
DETAIL: There exist a reference table in the outer part of the outer join
-- should be able to pushdown since reference table is in the
@ -337,15 +353,155 @@ ON user_buy_test_table.item_id = users_ref_test_table.id;
ERROR: cannot pushdown the subquery
DETAIL: There exist a subquery without FROM in the outer part of the outer join
-- can perform a union with subquery without FROM
-- with pulling data to coordinator
SET client_min_messages TO DEBUG;
SELECT count(*) FROM
(SELECT user_id FROM user_buy_test_table
UNION ALL
SELECT id FROM (SELECT 5 AS id) users_ref_test_table) subquery_1;
DEBUG: generating subplan 41_1 for subquery SELECT user_id FROM public.user_buy_test_table
DEBUG: Creating router plan
DEBUG: Plan is router executable
DEBUG: generating subplan 41_2 for subquery SELECT intermediate_result.user_id FROM read_intermediate_result('41_1'::text, 'binary'::citus_copy_format) intermediate_result(user_id integer) UNION ALL SELECT users_ref_test_table.id FROM (SELECT 5 AS id) users_ref_test_table
DEBUG: Plan 41 query after replacing subqueries and CTEs: SELECT count(*) AS count FROM (SELECT intermediate_result.user_id FROM read_intermediate_result('41_2'::text, 'binary'::citus_copy_format) intermediate_result(user_id integer)) subquery_1
DEBUG: Creating router plan
DEBUG: Plan is router executable
count
-------
5
(1 row)
-- union involving reference table and distributed table subqueries
-- is supported with pulling data to coordinator
SELECT * FROM
(SELECT id FROM users_ref_test_table
UNION
SELECT user_id FROM user_buy_test_table) sub
ORDER BY 1 DESC;
DEBUG: generating subplan 44_1 for subquery SELECT user_id FROM public.user_buy_test_table
DEBUG: Creating router plan
DEBUG: Plan is router executable
DEBUG: generating subplan 44_2 for subquery SELECT users_ref_test_table.id FROM public.users_ref_test_table UNION SELECT intermediate_result.user_id FROM read_intermediate_result('44_1'::text, 'binary'::citus_copy_format) intermediate_result(user_id integer)
DEBUG: Plan 44 query after replacing subqueries and CTEs: SELECT id FROM (SELECT intermediate_result.id FROM read_intermediate_result('44_2'::text, 'binary'::citus_copy_format) intermediate_result(id integer)) sub ORDER BY id DESC
DEBUG: Creating router plan
DEBUG: Plan is router executable
id
----
7
6
5
4
3
2
1
(7 rows)
-- same query but inner query has wrapped into another subquery
SELECT * FROM
(SELECT id, random() * 0 FROM (SELECT id FROM users_ref_test_table) sub1
UNION
SELECT user_id, random() * 0 FROM (SELECT user_id FROM user_buy_test_table) sub2) sub
ORDER BY 1 DESC;
DEBUG: generating subplan 47_1 for subquery SELECT user_id, (random() OPERATOR(pg_catalog.*) (0)::double precision) FROM (SELECT user_buy_test_table.user_id FROM public.user_buy_test_table) sub2
DEBUG: Creating router plan
DEBUG: Plan is router executable
DEBUG: generating subplan 47_2 for subquery SELECT sub1.id, (random() OPERATOR(pg_catalog.*) (0)::double precision) FROM (SELECT users_ref_test_table.id FROM public.users_ref_test_table) sub1 UNION SELECT intermediate_result.user_id, intermediate_result."?column?" FROM read_intermediate_result('47_1'::text, 'binary'::citus_copy_format) intermediate_result(user_id integer, "?column?" double precision)
DEBUG: Plan 47 query after replacing subqueries and CTEs: SELECT id, "?column?" FROM (SELECT intermediate_result.id, intermediate_result."?column?" FROM read_intermediate_result('47_2'::text, 'binary'::citus_copy_format) intermediate_result(id integer, "?column?" double precision)) sub ORDER BY id DESC
DEBUG: Creating router plan
DEBUG: Plan is router executable
id | ?column?
----+----------
7 | 0
6 | 0
5 | 0
4 | 0
3 | 0
2 | 0
1 | 0
(7 rows)
-- query can be pushed down when a reference table inside union query is
-- joined with a distributed table
SELECT * FROM
(SELECT user_id FROM users_ref_test_table ref JOIN user_buy_test_table dis
on (ref.id = dis.user_id)
UNION
SELECT user_id FROM user_buy_test_table) sub
ORDER BY 1 DESC;
user_id
---------
7
3
2
1
(4 rows)
-- same query with inner query wrapped with a subquery
SELECT * FROM
(SELECT user_id, random() * 0 FROM (SELECT dis.user_id FROM users_ref_test_table ref join user_buy_test_table dis
on (ref.id = dis.user_id)) sub1
UNION
SELECT user_id, random() * 0 FROM (SELECT user_id FROM user_buy_test_table) sub2) sub
ORDER BY 1 DESC;
user_id | ?column?
---------+----------
7 | 0
3 | 0
2 | 0
1 | 0
(4 rows)
SELECT * FROM
(SELECT user_id FROM users_ref_test_table ref JOIN user_buy_test_table dis
on (ref.id = dis.user_id) WHERE id in (SELECT user_id from user_buy_test_table)
UNION
SELECT user_id FROM user_buy_test_table) sub
ORDER BY 1 DESC;
ERROR: cannot pushdown the subquery
DETAIL: There exist a reference table in the outer part of the outer join
SELECT * FROM
(SELECT user_id FROM users_ref_test_table ref JOIN user_buy_test_table dis
on (ref.id = dis.user_id)
UNION
SELECT user_id FROM user_buy_test_table WHERE user_id in (select id from users_ref_test_table)) sub
ORDER BY 1 DESC;
user_id
---------
3
2
1
(3 rows)
-- query can be pushed down when a reference table inside union query is
-- joined with a distributed table. outer join is also supported
-- if reference table is in the inner part
SELECT * FROM
(SELECT user_id FROM users_ref_test_table ref RIGHT JOIN user_buy_test_table dis
on (ref.id = dis.user_id)
UNION
SELECT user_id FROM user_buy_test_table) sub
ORDER BY 1 DESC;
user_id
---------
7
3
2
1
(4 rows)
-- query can be pushed down when a reference table inside union query is
-- joined with a distributed table. reference table cannot be at
-- the outer part.
SELECT * FROM
(SELECT user_id FROM users_ref_test_table ref LEFT JOIN user_buy_test_table dis
on (ref.id = dis.user_id)
UNION
SELECT user_id FROM user_buy_test_table) sub
ORDER BY 1 DESC;
ERROR: cannot pushdown the subquery
DETAIL: There exist a reference table in the outer part of the outer join
RESET client_min_messages;
-- should be able to pushdown since reference table is in the
-- inner part of the left join
SELECT
@ -453,7 +609,7 @@ SELECT * FROM
(SELECT user_id as user_user_id FROM users_table) as fooo ON (user_id = user_user_id)) as bar;
ERROR: cannot pushdown the subquery
DETAIL: There exist a reference table in the outer part of the outer join
-- we could even suuport the following where the subquery
-- we could even support the following where the subquery
-- on the outer part of the left join contains a reference table
SELECT max(events_all.cnt), events_all.usr_id
FROM
@ -471,17 +627,16 @@ LEFT JOIN events_table ON (events_all.usr_id = events_table.user_id) GROUP BY 2
105 | 1
(5 rows)
-- but, we fail to pushdown the following query where join that reference table appears
-- wrapped into a subquery
-- we still support the query when the join involving reference table is wrapped with a subquery
SELECT max(events_all.cnt),
events_all.usr_id
FROM(
SELECT *, random() FROM
(SELECT users_table.user_id AS usr_id, count(*) AS cnt
FROM events_reference_table
INNER JOIN users_table ON (users_table.user_id = events_reference_table.user_id)
GROUP BY users_table.user_id) AS events_all_inner) AS events_all
LEFT JOIN events_table ON (events_all.usr_id = events_table.user_id)
FROM (SELECT *, random()
FROM (SELECT users_table.user_id AS usr_id, count(*) AS cnt
FROM events_reference_table
INNER JOIN users_table ON (users_table.user_id = events_reference_table.user_id)
GROUP BY users_table.user_id) AS events_all_inner
) AS events_all
LEFT JOIN events_table ON (events_all.usr_id = events_table.user_id)
GROUP BY 2
ORDER BY 1 DESC,
2 DESC
@ -1179,8 +1334,8 @@ SELECT count(*) FROM
(SELECT user_buy_test_table.user_id, random() FROM user_buy_test_table LEFT JOIN users_ref_test_table
ON user_buy_test_table.user_id > users_ref_test_table.id) subquery_2
WHERE subquery_1.user_id != subquery_2.user_id ;
DEBUG: generating subplan 79_1 for subquery SELECT user_buy_test_table.user_id, random() AS random FROM (public.user_buy_test_table LEFT JOIN public.users_ref_test_table ON ((user_buy_test_table.user_id OPERATOR(pg_catalog.>) users_ref_test_table.id)))
DEBUG: Plan 79 query after replacing subqueries and CTEs: SELECT count(*) AS count FROM (SELECT user_buy_test_table.user_id, random() AS random FROM (public.user_buy_test_table LEFT JOIN public.users_ref_test_table ON ((user_buy_test_table.item_id OPERATOR(pg_catalog.>) users_ref_test_table.id)))) subquery_1, (SELECT intermediate_result.user_id, intermediate_result.random FROM read_intermediate_result('79_1'::text, 'binary'::citus_copy_format) intermediate_result(user_id integer, random double precision)) subquery_2 WHERE (subquery_1.user_id OPERATOR(pg_catalog.<>) subquery_2.user_id)
DEBUG: generating subplan 86_1 for subquery SELECT user_buy_test_table.user_id, random() AS random FROM (public.user_buy_test_table LEFT JOIN public.users_ref_test_table ON ((user_buy_test_table.user_id OPERATOR(pg_catalog.>) users_ref_test_table.id)))
DEBUG: Plan 86 query after replacing subqueries and CTEs: SELECT count(*) AS count FROM (SELECT user_buy_test_table.user_id, random() AS random FROM (public.user_buy_test_table LEFT JOIN public.users_ref_test_table ON ((user_buy_test_table.item_id OPERATOR(pg_catalog.>) users_ref_test_table.id)))) subquery_1, (SELECT intermediate_result.user_id, intermediate_result.random FROM read_intermediate_result('86_1'::text, 'binary'::citus_copy_format) intermediate_result(user_id integer, random double precision)) subquery_2 WHERE (subquery_1.user_id OPERATOR(pg_catalog.<>) subquery_2.user_id)
count
-------
67
@ -1225,8 +1380,8 @@ count(*) AS cnt, "generated_group_field"
ORDER BY
cnt DESC, generated_group_field ASC
LIMIT 10;
DEBUG: generating subplan 81_1 for subquery SELECT user_id, value_2 AS generated_group_field FROM public.users_table users
DEBUG: Plan 81 query after replacing subqueries and CTEs: SELECT count(*) AS cnt, generated_group_field FROM (SELECT "eventQuery".user_id, random() AS random, "eventQuery".generated_group_field FROM (SELECT multi_group_wrapper_1."time", multi_group_wrapper_1.event_user_id, multi_group_wrapper_1.user_id, left_group_by_1.generated_group_field, random() AS random FROM ((SELECT temp_data_queries."time", temp_data_queries.event_user_id, user_filters_1.user_id FROM ((SELECT events."time", events.user_id AS event_user_id FROM public.events_table events WHERE (events.user_id OPERATOR(pg_catalog.>) 2)) temp_data_queries JOIN (SELECT users.user_id FROM public.users_reference_table users WHERE ((users.user_id OPERATOR(pg_catalog.>) 2) AND (users.value_2 OPERATOR(pg_catalog.=) 5))) user_filters_1 ON ((temp_data_queries.event_user_id OPERATOR(pg_catalog.<) user_filters_1.user_id)))) multi_group_wrapper_1 RIGHT JOIN (SELECT intermediate_result.user_id, intermediate_result.generated_group_field FROM read_intermediate_result('81_1'::text, 'binary'::citus_copy_format) intermediate_result(user_id integer, generated_group_field integer)) left_group_by_1 ON ((left_group_by_1.user_id OPERATOR(pg_catalog.>) multi_group_wrapper_1.event_user_id)))) "eventQuery") "pushedDownQuery" GROUP BY generated_group_field ORDER BY (count(*)) DESC, generated_group_field LIMIT 10
DEBUG: generating subplan 88_1 for subquery SELECT user_id, value_2 AS generated_group_field FROM public.users_table users
DEBUG: Plan 88 query after replacing subqueries and CTEs: SELECT count(*) AS cnt, generated_group_field FROM (SELECT "eventQuery".user_id, random() AS random, "eventQuery".generated_group_field FROM (SELECT multi_group_wrapper_1."time", multi_group_wrapper_1.event_user_id, multi_group_wrapper_1.user_id, left_group_by_1.generated_group_field, random() AS random FROM ((SELECT temp_data_queries."time", temp_data_queries.event_user_id, user_filters_1.user_id FROM ((SELECT events."time", events.user_id AS event_user_id FROM public.events_table events WHERE (events.user_id OPERATOR(pg_catalog.>) 2)) temp_data_queries JOIN (SELECT users.user_id FROM public.users_reference_table users WHERE ((users.user_id OPERATOR(pg_catalog.>) 2) AND (users.value_2 OPERATOR(pg_catalog.=) 5))) user_filters_1 ON ((temp_data_queries.event_user_id OPERATOR(pg_catalog.<) user_filters_1.user_id)))) multi_group_wrapper_1 RIGHT JOIN (SELECT intermediate_result.user_id, intermediate_result.generated_group_field FROM read_intermediate_result('88_1'::text, 'binary'::citus_copy_format) intermediate_result(user_id integer, generated_group_field integer)) left_group_by_1 ON ((left_group_by_1.user_id OPERATOR(pg_catalog.>) multi_group_wrapper_1.event_user_id)))) "eventQuery") "pushedDownQuery" GROUP BY generated_group_field ORDER BY (count(*)) DESC, generated_group_field LIMIT 10
ERROR: cannot pushdown the subquery
DETAIL: Complex subqueries and CTEs cannot be in the outer part of the outer join
RESET client_min_messages;

138
src/test/regress/sql/multi_subquery_complex_reference_clause.sql
View File

@ -90,24 +90,40 @@ SELECT count(*) FROM
ON user_buy_test_table.user_id > users_ref_test_table.id AND users_ref_test_table.k_no > 44 AND user_buy_test_table.user_id > 44) subquery_2
WHERE subquery_1.user_id = subquery_2.user_id ;
-- Should be able to push down since reference tables are inner joined
-- with hash distributed tables, the results of those joins are the parts of
-- an outer join
SELECT subquery_2.id FROM
(SELECT tt1.user_id, random() FROM user_buy_test_table AS tt1 JOIN users_return_test_table as tt2
ON tt1.user_id = tt2.user_id) subquery_1
RIGHT JOIN
(SELECT tt1.user_id, ref.id, random() FROM user_buy_test_table as tt1 JOIN users_ref_test_table as ref
ON tt1.user_id = ref.id) subquery_2 ON subquery_1.user_id = subquery_2.user_id ORDER BY 1 DESC LIMIT 5;
-- Should be able to push down since reference tables are inner joined
-- with hash distributed tables, the results of those joins are the parts of
-- an outer join
SELECT subquery_2.id
FROM
(SELECT tt1.user_id, random()
FROM user_buy_test_table AS tt1
JOIN users_return_test_table as tt2
ON tt1.user_id = tt2.user_id) subquery_1
RIGHT JOIN
(SELECT tt1.user_id, ref.id, random()
FROM user_buy_test_table as tt1
JOIN users_ref_test_table as ref
ON tt1.user_id = ref.id) subquery_2
ON subquery_1.user_id = subquery_2.user_id
ORDER BY 1 DESC LIMIT 5;
-- the same query as the above, but this Citus fails to pushdown the query
-- since the outer part of the right join doesn't include any joins
SELECT * FROM
(SELECT tt1.user_id, random() FROM user_buy_test_table AS tt1 JOIN users_return_test_table as tt2
ON tt1.user_id = tt2.user_id) subquery_1
RIGHT JOIN
(SELECT *, random() FROM (SELECT tt1.user_id, random() FROM user_buy_test_table as tt1 JOIN users_ref_test_table as ref
ON tt1.user_id = ref.id) subquery_2_inner) subquery_2 ON subquery_1.user_id = subquery_2.user_id;
-- almost the same query as the above, but reference table join wrapped with
-- another subquery
SELECT subquery_1.user_id
FROM
(SELECT tt1.user_id, random()
FROM user_buy_test_table AS tt1
JOIN users_return_test_table as tt2
ON tt1.user_id = tt2.user_id) subquery_1
RIGHT JOIN
(SELECT *, random()
FROM
(SELECT tt1.user_id, random()
FROM user_buy_test_table as tt1
JOIN users_ref_test_table as ref
ON tt1.user_id = ref.id) subquery_2_inner) subquery_2
ON subquery_1.user_id = subquery_2.user_id
ORDER BY 1;
-- should be able to pushdown since reference table is in the
-- inner part of the left join
@ -198,10 +214,79 @@ SELECT count(*) FROM user_buy_test_table RIGHT JOIN (SELECT 5 AS id) users_ref_t
ON user_buy_test_table.item_id = users_ref_test_table.id;
-- can perform a union with subquery without FROM
-- with pulling data to coordinator
SET client_min_messages TO DEBUG;
SELECT count(*) FROM
(SELECT user_id FROM user_buy_test_table
UNION ALL
SELECT id FROM (SELECT 5 AS id) users_ref_test_table) subquery_1;
-- union involving reference table and distributed table subqueries
-- is supported with pulling data to coordinator
SELECT * FROM
(SELECT id FROM users_ref_test_table
UNION
SELECT user_id FROM user_buy_test_table) sub
ORDER BY 1 DESC;
-- same query but inner query has wrapped into another subquery
SELECT * FROM
(SELECT id, random() * 0 FROM (SELECT id FROM users_ref_test_table) sub1
UNION
SELECT user_id, random() * 0 FROM (SELECT user_id FROM user_buy_test_table) sub2) sub
ORDER BY 1 DESC;
-- query can be pushed down when a reference table inside union query is
-- joined with a distributed table
SELECT * FROM
(SELECT user_id FROM users_ref_test_table ref JOIN user_buy_test_table dis
on (ref.id = dis.user_id)
UNION
SELECT user_id FROM user_buy_test_table) sub
ORDER BY 1 DESC;
-- same query with inner query wrapped with a subquery
SELECT * FROM
(SELECT user_id, random() * 0 FROM (SELECT dis.user_id FROM users_ref_test_table ref join user_buy_test_table dis
on (ref.id = dis.user_id)) sub1
UNION
SELECT user_id, random() * 0 FROM (SELECT user_id FROM user_buy_test_table) sub2) sub
ORDER BY 1 DESC;
SELECT * FROM
(SELECT user_id FROM users_ref_test_table ref JOIN user_buy_test_table dis
on (ref.id = dis.user_id) WHERE id in (SELECT user_id from user_buy_test_table)
UNION
SELECT user_id FROM user_buy_test_table) sub
ORDER BY 1 DESC;
SELECT * FROM
(SELECT user_id FROM users_ref_test_table ref JOIN user_buy_test_table dis
on (ref.id = dis.user_id)
UNION
SELECT user_id FROM user_buy_test_table WHERE user_id in (select id from users_ref_test_table)) sub
ORDER BY 1 DESC;
-- query can be pushed down when a reference table inside union query is
-- joined with a distributed table. outer join is also supported
-- if reference table is in the inner part
SELECT * FROM
(SELECT user_id FROM users_ref_test_table ref RIGHT JOIN user_buy_test_table dis
on (ref.id = dis.user_id)
UNION
SELECT user_id FROM user_buy_test_table) sub
ORDER BY 1 DESC;
-- query can be pushed down when a reference table inside union query is
-- joined with a distributed table. reference table cannot be at
-- the outer part.
SELECT * FROM
(SELECT user_id FROM users_ref_test_table ref LEFT JOIN user_buy_test_table dis
on (ref.id = dis.user_id)
UNION
SELECT user_id FROM user_buy_test_table) sub
ORDER BY 1 DESC;
RESET client_min_messages;
-- should be able to pushdown since reference table is in the
-- inner part of the left join
@ -291,7 +376,7 @@ SELECT * FROM
user_id > 2 and value_2 = 1) as foo_in ON (event_val_2 = user_id)) as foo LEFT JOIN
(SELECT user_id as user_user_id FROM users_table) as fooo ON (user_id = user_user_id)) as bar;
-- we could even suuport the following where the subquery
-- we could even support the following where the subquery
-- on the outer part of the left join contains a reference table
SELECT max(events_all.cnt), events_all.usr_id
FROM
@ -301,17 +386,16 @@ FROM
INNER JOIN users_table ON (users_table.user_id = events_reference_table.user_id) GROUP BY users_table.user_id) AS events_all
LEFT JOIN events_table ON (events_all.usr_id = events_table.user_id) GROUP BY 2 ORDER BY 1 DESC, 2 DESC LIMIT 5;
-- but, we fail to pushdown the following query where join that reference table appears
-- wrapped into a subquery
-- we still support the query when the join involving reference table is wrapped with a subquery
SELECT max(events_all.cnt),
events_all.usr_id
FROM(
SELECT *, random() FROM
(SELECT users_table.user_id AS usr_id, count(*) AS cnt
FROM events_reference_table
INNER JOIN users_table ON (users_table.user_id = events_reference_table.user_id)
GROUP BY users_table.user_id) AS events_all_inner) AS events_all
LEFT JOIN events_table ON (events_all.usr_id = events_table.user_id)
FROM (SELECT *, random()
FROM (SELECT users_table.user_id AS usr_id, count(*) AS cnt
FROM events_reference_table
INNER JOIN users_table ON (users_table.user_id = events_reference_table.user_id)
GROUP BY users_table.user_id) AS events_all_inner
) AS events_all
LEFT JOIN events_table ON (events_all.usr_id = events_table.user_id)
GROUP BY 2
ORDER BY 1 DESC,
2 DESC