[postgres-xl-general] something wrong with my Postgres-XL
Alexander Voytsekhovskyy
av at mobile-ua.com
Fri Oct 27 22:57:39 PDT 2017
Let’s go with your example first, seems i have a problem even with it
you missed SELECT SQL query, so i tried to suggest it and here is my query plan
ddc_splat=# explain analyze select sum(b) from t1 group by a;
QUERY PLAN
-------------------------------------------------------------------------------------------------------------------------------------------
Remote Subquery Scan on all (datanode1,datanode2) (cost=40.60..42.60 rows=200 width=12) (actual time=798.780..841.870 rows=1000 loops=1)
Planning time: 0.144 ms
Execution time: 845.622 ms
(3 rows)
any ideas what’s wrong with my Postgres-XL?
>
> FWIW after doing this on a 2-node cluster:
>
> create table t (a int, b int, c int);
> create table t1 () inherits (t) to node (datanode_1);
> create table t2 () inherits (t) to node (datanode_2);
>
> insert into t1 select mod(i,1000), i, i
> from generate_series(1,10000000) s(i);
>
> insert into t2 select mod(i,1000), i, i
> from generate_series(1,10000000) s(i);
>
> vacuum analyze t;
>
> I do get a plan like this:
>
> QUERY PLAN
> -------------------------------------------------------------
> Finalize GroupAggregate
> Group Key: a
> -> Remote Subquery Scan on all (dn1,dn2)
> -> Sort
> Sort Key: t.a
> -> Gather
> Workers Planned: 4
> -> Partial HashAggregate
> Group Key: t.a
> -> Append
> -> Parallel Seq Scan on t
> -> Parallel Seq Scan on t1
> -> Parallel Seq Scan on t2
> (13 rows)
>
> Which seems mostly reasonable, I believe.
>
> regards
>
> --
> Tomas Vondra http://www.2ndQuadrant.com
> PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
More information about the postgres-xl-general
mailing list