I hava below two statement sql:
0. not in subquery
select a.schemaname, pg_size_pretty(pg_total_relation_size(a.schemaname||'.'||a.tablename)) from pg_tables a where a.tablename not in (select b.tablename from t b);
1. in subquery
select a.schemaname, pg_size_pretty(pg_total_relation_size(a.schemaname||'.'||a.tablename)) from pg_tables a where a.tablename in (select b.tablename from t b);
The [0. not in subquery] can't work well, it's occur error:
ERROR: query plan with multiple segworker groups is not supported (cdbdisp.c:500)
HINT: likely caused by a function that reads or modifies data in a distributed table
CONTEXT: SQL statement "select sum(pg_total_relation_size('information_schema.sql_languages'))::int8 from gp_dist_random('gp_id');"
The [1. in subquery] work well.
Detailed below test:
gtlions=# select version();
version
------------------------------------------------------------------------------------------------------------------------------------------------------
PostgreSQL 8.2.15 (Greenplum Database 4.2.7.3 build 1) on x86_64-unknown-linux-gnu, compiled by GCC gcc (GCC) 4.4.2 compiled on May 7 2014 14:31:08
(1 row)
gtlions=# select a.schemaname, pg_size_pretty(pg_total_relation_size(a.schemaname||'.'||a.tablename)) from pg_tables a where a.tablename not in (select b.tablename from t b);
ERROR: query plan with multiple segworker groups is not supported (cdbdisp.c:500)
HINT: likely caused by a function that reads or modifies data in a distributed table
CONTEXT: SQL statement "select sum(pg_total_relation_size('information_schema.sql_languages'))::int8 from gp_dist_random('gp_id');"
gtlions=# explain select a.schemaname, pg_size_pretty(pg_total_relation_size(a.schemaname||'.'||a.tablename)) from pg_tables a where a.tablename not in (select b.tablename from t b);
QUERY PLAN
-----------------------------------------------------------------------------------------------
Hash Left Anti Semi Join (cost=568.98..235912.69 rows=676396 width=128)
Hash Cond: c.relname = "NotIn_SUBQUERY".tablename::name
-> Hash Left Join (cost=395.97..223194.68 rows=676419 width=128)
Hash Cond: c.relnamespace = n.oid
-> Hash Left Join (cost=2.62..112777.67 rows=676419 width=68)
Hash Cond: c.reltablespace = t.oid
-> Seq Scan on pg_class c (cost=0.00..2751.39 rows=676419 width=72)
Filter: relkind = 'r'::"char" AND relname IS NOT NULL
-> Hash (cost=1.02..1.02 rows=2 width=4)
-> Seq Scan on pg_tablespace t (cost=0.00..1.02 rows=128 width=4)
-> Hash (cost=365.35..365.35 rows=35 width=68)
-> Seq Scan on pg_namespace n (cost=0.00..365.35 rows=2240 width=68)
-> Hash (cost=106.61..106.61 rows=83 width=274)
-> Gather Motion 64:1 (slice1; segments: 64) (cost=0.00..106.61 rows=83 width=274)
-> Subquery Scan "NotIn_SUBQUERY" (cost=0.00..52.66 rows=2 width=274)
-> Seq Scan on t b (cost=0.00..51.83 rows=2 width=24)
(16 rows)
gtlions=# select a.schemaname, pg_size_pretty(pg_total_relation_size(a.schemaname||'.'||a.tablename)) from pg_tables a where a.tablename in (select b.tablename from t b);
schemaname | size-1
-------------+---------
public | 32 kB
public | 32 kB
......
......
public | 96 kB
gtlions=# explain select a.schemaname, pg_size_pretty(pg_total_relation_size(a.schemaname||'.'||a.tablename)) from pg_tables a where a.tablename in (select b.tablename from t b);
QU