To: pgsql-admin@postgresql.org
From: Thomas Kellerer <spam_eater@gmx.net>
Subject: Re: Performance killed with FDW when using CAST.
Date: Wed, 17 Apr 2019 08:23:02 +0200
Message-ID: <q96go6$6fn4$1@blaine.gmane.org>
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Laurenz Albe schrieb am 17.04.2019 um 07:03:
>> We setup a FDW server for a large table that has an hstore data type as on eof the coums.
>>
>> When we run the query directly on the FDW server
>>
>> select * from recent_events where account_id = 1 AND (attributes -> 'account_incident_id')::integer = 2617116 limit 10;
>>
>> The response is 2ms . which is awesome.
>>
>> When we run it from the remote server where we have the server defined, the query never returns.
>>
>> Our server definition is as follows.
>>
>> (host 'fdwserver', dbname 'mydb', port '5432', fetch_size '1000', use_remote_estimate 'true', extensions 'hstore')
> 
> After debugging into this, it seems that the hstore operator -> cannot
> be pushed down because of collation problems.

Do you happen to know if the JSONB operator -> (or ->>) can be pushed down? 

Although I realize it would be a major change in the database design, maybe that would be a solution for Jorge. 

Thomas