Re: query reboot pgsql 9.5.1

On 03/04/2016 12:09 PM, Felipe de Jesús Molina Bravo wrote:
> Hi!!!
>
> I try to explain my problem...sorry for my english :(
>
>
> In pgsql 9.5.1 I have a two tables with the next structure:
>
> 1. Tabla unlogged «public._gc_cat»
> Columna | Tipo | Modificadores
> -----------------+--------------+---------------
> idppicat | integer |
> idprodxintegrar | integer |
> tipo | character(1) |
> valor | numeric |
> estado | character(1) |
> idsll | text |
> idsfte | text |
> arama | text[] |
> ne_arama | integer |
> rama | text |
> rvar | text |
> nodec | integer |
>
> Índices:
> "_gc_cat_arama" btree (ne_arama)
> "_gc_cat_arama_gin" gin (arama)
>
> 2. Tabla unlogged «public._gc_tb»
> Columna | Tipo | Modificadores
> ----------+---------+---------------
> idb2 | integer |
> idc1 | integer |
> rama | text |
> arama | text[] |
> ne_arama | integer |
> Índices:
> "_gc_tb_arama" btree (ne_arama)
> "_gc_tb_arama_gin" gin (arama)
> "_gc_tb_idb2idc1" btree (idb2, idc1)
>
>
> the tabla _gc_cat have 91932 records an _gc_tb have 120130 records; when
> i run the
> next query:
>
> SELECT idprodxintegrar
> FROM _gc_tb a
> LEFT join
> _gc_cat b
> on ( b.arama <@ a.arama and a.arama < @ b.arama )
>
> psql send the next message (after three minutes aprox.):
> Terminado (killed)
>
> and i have to reboot my "guest server".
>
> Now i execute the same in pgsql 9.4.5 and all is fine!!!
>
> The EXPLAINs are:
>
> - pgsql 9.5.1:
>
> Nested Loop Left Join (cost=0.03..492944.81 rows=276095 width=4)
> -> Seq Scan on _gc_tb a (cost=0.00..3321.30 rows=120130 width=66)
> -> Bitmap Heap Scan on _gc_cat b (cost=0.03..4.06 rows=2 width=70)
> Recheck Cond: ((arama <@ a.arama) AND (a.arama <@ arama))
> -> Bitmap Index Scan on _gc_cat_arama_gin
> (cost=0.00..0.03 rows=2 width=0)
> Index Cond: ((arama <@ a.arama) AND
> (a.arama <@ arama))
>
>
> - pgsql 9.4.5:
> Nested Loop Left Join (cost=0.03..492944.81 rows=276095 width=4)
> -> Seq Scan on _gc_tb a (cost=0.00..3321.30 rows=120130 width=66)
> -> Bitmap Heap Scan on _gc_cat b (cost=0.03..4.06 rows=2 width=70)
> Recheck Cond: ((arama <@ a.arama) AND (a.arama <@ arama))
> -> Bitmap Index Scan on _gc_cat_arama_gin
> (cost=0.00..0.03 rows=2 width=0)
> Index Cond: ((arama <@ a.arama) AND
> (a.arama <@ arama))

The above are exactly the same, so if they are indeed from the different
versions I do not see an issue. The question to ask here is whether the
above are actually from the different Postgres instances?

>
> If i change the query as:
> SELECT idprodxintegrar
> FROM _gc_tb a
> LEFT join
> _gc_cat b
> on ( a.ne_arama = b.ne_arama and a.arama <@ b.arama )
>
> In pgsql 9.5.1 finished after 450708.112 ms
>
> In pgsql 9.4.5 finished after 17996.756 ms (very fast!!!)
>
> The EXPLAINs are:
> - pgsql 9.5.1
> Nested Loop Left Join (cost=3.49..1915550.34 rows=41825277 width=4)
> -> Seq Scan on _gc_tb a (cost=0.00..3321.30 rows=120130 width=70)
> -> Bitmap Heap Scan on _gc_cat b (cost=3.49..14.39 rows=153
> width=74)
> Recheck Cond: (a.arama <@ arama)
> Filter: (a.ne_arama = ne_arama)
> -> Bitmap Index Scan on _gc_cat_arama_gin
> (cost=0.00..3.45 rows=460 width=0)
> Index Cond: (a.arama <@ arama)
>
> - pgsql 9.4.5
> Nested Loop Left Join (cost=3.48..1868759.71 rows=42284738 width=4)
> -> Seq Scan on _gc_tb a (cost=0.00..3321.30 rows=120130 width=70)
> -> Bitmap Heap Scan on _gc_cat b (cost=3.48..14.38 rows=115
> width=74)
> Recheck Cond: (a.arama <@ arama)
> Filter: (a.ne_arama = ne_arama)
> -> Bitmap Index Scan on _gc_cat_arama_gin
> (cost=0.00..3.45 rows=460 width=0)
> Index Cond: (a.arama <@ arama)
>
>
> The shared_buffers and work_mem are the same in both versions of pgsql
> (128MB and
> 4MB)
>
> I am doing this test in a laptop with the next characteristics:
>
> - hp probook with 8 Gb ram. SATA disk, AMD A8-5550M
> - OS Linux (fedora 23)
> - lxc containers

So is each Postgres instance running in a separate container and if so
are they set up the same?

>
>
> I am sharing the dumper's database are in the next links:
>
> http://sipre.inegi.org.mx/pgsql/dump_pgsql_9_4_5.dump
>
> http://sipre.inegi.org.mx/pgsql/dump_pgsql_9_5_1.dump
>
>
> similar post is found in:
>
> http://www.postgresql.org/message-id/CALrs2KPMowV6juLdOkMRq_P3MA5VkUmhdM4Q1OD0vCf2qimFfA@mail.gmail.
> com
>
> thanks in advance!

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com