join tables vs. denormalization by trigger

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От Walter Mauritz
Тема join tables vs. denormalization by trigger
Дата
Msg-id 20070904185321.221220@gmx.net
обсуждение исходный текст
Ответы Re: join tables vs. denormalization by trigger  (Mark Lewis <mark.lewis@mir3.com>)
Re: join tables vs. denormalization by trigger  ("Marc Mamin" <M.Mamin@intershop.de>)
Список pgsql-performance
Hi,

I wonder about differences in performance between two scenarios:

Background:
Table A, ~50,000 records
Table B, ~3,000,000 records (~20 cols)
Table C, ~30,000,000 records (~10 cols)

a query every 3sec. with limit 10

Table C depends on Table B wich depends on Table A, int8 foreign key, btree index

* consider it a read only scenario (load data only in night, with time for vacuum analyze daily)
* im required to show records from Table C, but also with some (~5cols) info from Table B
* where clause always contains the foreign key to Table A
* where clause may contain further 1-10 search parameter


Scenario A)
simply inner join Table B + C

Scenario B)
with use of trigger on insert/update I could push the required information from table B down to table C.
-> so i would only require to select from table C.


My question:
1) From your experience ... how much faster (approximately) in percent do you regard Scenario B faster than A ?

2) any other tips for such a read only scenario

Thx for any attention :-)
Walter
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