Re: An issue in remote query optimization

On Tue, Jan 31, 2017 at 3:15 AM, Etsuro Fujita <fujita(dot)etsuro(at)lab(dot)ntt(dot)co(dot)jp>
wrote:

> On 2017/01/31 19:53, Abbas Butt wrote:
>
>> On Tue, Jan 31, 2017 at 2:25 AM, Etsuro Fujita
>> <fujita(dot)etsuro(at)lab(dot)ntt(dot)co(dot)jp <mailto:fujita(dot)etsuro(at)lab(dot)ntt(dot)co(dot)jp>> wrote:
>> On 2017/01/31 18:24, Abbas Butt wrote:
>>
>
> Postgres_fdw optimizes remote queries by pushing down the where
>> clause.
>> This feature does not work consistently when the query is
>> executed from
>> within a pl/pgsql function. The optimization works when the
>> function
>> executes the query for the first 5 times, and fails afterwards.
>>
>
> I understand that this is because PostgreSQL starts using
>> generic plan
>> with pulled up where clause after the 5th invocation hoping that
>> it
>> would be faster since we have skiped planning the query on each
>> invocation, but in this case this decision is causing the query
>> to slow
>> down.
>>
>
> How should we fix this problem?
>>
>
> ANALYZE for the foreign table doesn't work?
>>
>
> No.
>>
>> analyze ts.tickets;
>> WARNING: skipping "tickets" --- cannot analyze this foreign table
>> ANALYZE
>>
>
> How the foreign table ts.tickets is defined?
>

test=# \d ts.tickets
Foreign table "ts.tickets"
Column | Type | Modifiers | FDW Options
--------+---------+-----------+-------------
id | integer | not null |
Server: mysql_server
FDW Options: (dbname 'msql_test_db', table_name 'tickets')

Its a foreign table, referring to table 'tickets' defined on MySQL.

> Best regards,
> Etsuro Fujita
>
>
>

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