Re: Planning time is high in Postgres 11.5 Compared with Postgres 10.11

út 17. 12. 2019 v 7:11 odesílatel avinash varma <[email protected]>
napsal:

> Hi Tom,
>
>   You didn't answer the question:
>
> >> First thing to do is to look into pg_stats and see how large those
> >> arrays actually are in each case ...
>
> We reproduced issue with sample tables "child" and "core", moreover these
> tables  doesn't contains any data in it in both postgresql 10 & 11.
>
> select count(1) from child --0
> select count(1) from core --0
>
> I did analyzed both the tables using the below command and after which i
> ran the below explain analyze and took the perf report.
>
> Vacuum analyze child;
> vacuum analyze core;
>
> Both configuration parameters are identical in V10 & V11. But we observe
> high planning time in V11 when compared with V10.
>
> PostDB11=# explain analyze  SELECT --DISTINCT kc.childid AS rlid,
> PostDB11-#     kc.id AS rlrightid--,
> PostDB11-#    -- 0 AS rlproxytype
> PostDB11-#    FROM child kc
> PostDB11-#   WHERE NOT (EXISTS ( SELECT 1
> PostDB11(#            FROM core
> PostDB11(#           WHERE kc.id = core.groupid));
>
>
> Postgres 10
>
> -bash-4.2$ perf report -g
> Samples: 6K of event 'cpu-clock:uhH', Event count (approx.): 1541000000
>   Children      Self  Command   Shared Object          Symbol
>
>
>
>
> *+   13.72%     0.00%  postgres  [unknown]              [.]
> 0000000000000000+    5.34%     0.08%  postgres  libc-2.17.so
> <http://libc-2.17.so>           [.] __vsnprintf_chk+    4.62%     1.52%
>  postgres  libc-2.17.so <http://libc-2.17.so>           [.] vfprintf+
>  4.59%     4.59%  postgres  postgres               [.] SearchCatCache+
>  4.12%     0.00%  postgres  [unknown]              [.] 0x0000000001d86000*
> +    4.09%     4.09%  postgres  postgres               [.] base_yyparse
> +    2.09%     0.00%  postgres  [unknown]              [.]
> 0x312e2e32362e3135
> +    2.04%     2.03%  postgres  postgres               [.]
> hash_search_with_hash_value
>      1.83%     1.83%  postgres  libc-2.17.so           [.] __strcmp_sse42
> +    1.78%     0.00%  postgres  [unknown]              [.]
> 0x0000000001d83638
> +    1.74%     0.00%  postgres  [unknown]              [.]
> 0x0000000000cb3260
> +    1.49%     1.43%  postgres  libc-2.17.so           [.]
> __GI___printf_fp_l
>
>
>
> Postgres 11
>
>
> bash-4.2$ perf report -g
> Samples: 235K of event 'cpu-clock:uhH', Event count (approx.): 58888750000
>   Children      Self  Command   Shared Object       Symbol
> +   37.73%    37.73%  postgres  postgres            [.] FunctionCall2Coll
> +   28.57%    28.57%  postgres  postgres            [.] eqjoinsel
> +   13.94%    13.94%  postgres  postgres            [.] int8eq
> +    5.68%     5.68%  postgres  postgres            [.]
> eqjoinsel_semi.isra.3
> +    1.78%     0.14%  postgres  libc-2.17.so        [.] __clock_gettime
> +    1.76%     1.76%  postgres  postgres            [.] pglz_decompress
> +    1.68%     1.68%  postgres  [vdso]              [.]
> __vdso_clock_gettime
> +    1.43%     0.00%  postgres  [unknown]           [.] 0000000000000000
> +    1.22%     0.00%  postgres  postgres            [.] TTSOpsVirtual+0x0
> +    0.93%     0.00%  postgres  postgres            [.]
> TTSOpsBufferHeapTuple+0x0
> +    0.72%     0.00%  postgres  [unknown]           [.] 0x00000000026bb0d0
>      0.44%     0.44%  postgres  postgres            [.] deconstruct_array
>
> Thanks,
> Avinash
>

is same collation in both databases?

Maybe there are some issues in virtualization

Pavel