Re: How to read query plan

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От Kaloyan Iliev Iliev
Тема Re: How to read query plan
Дата
Msg-id 4235C3E9.2080505@faith.digsys.bg
обсуждение исходный текст
Ответ на Re: How to read query plan  (Miroslav Šulc <miroslav.sulc@startnet.cz>)
Ответы Re: How to read query plan  (Miroslav Šulc <miroslav.sulc@startnet.cz>)
Список pgsql-performance
Hi,

I have an idea about your problem. Will it be difficult not to change the entire code but only the queries? You can change type in the Postgres to bool. Then, when select data you can use a CASE..WHEN to return 'Y' or 'N' or even write a little function which accepts bool and returns 'Y' or 'N'. In this case in all your queries you will have to replace the select of bool field with select form the function.

Kaloyan

Miroslav Љulc wrote:
Tom Lane wrote:

Just FYI, I did a quick search-and-replace on your dump to replace
varchar(1) by "char", which makes the column fixed-width without any
change in the visible data.  This made hardly any difference in the
join speed though :-(.  So that is looking like a dead end.
 

I'll try to change the data type to bool but the problem I stand in front of is that the code expects that SELECTs return 'Y' or 'N' but what I have found out till now is that PostgreSQL returns 't' or 'f' for bool data. I think about some solution but they use CPU :-(

John's idea about re-joining to the main table to pick up the bulk of
its fields only after joining to the sub-tables might work.
 

I'll try that. It seems it could work.

            regards, tom lane
 

Miroslav

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