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Article #183082

Re: Oracle 10 - Materialny widok - Query Rewrite

#183082
From: Thomas Olszewicki
Date: Wed, 24 Jun 2009 13:19
52 lines
3260 bytes
On Jun 24, 8:46 am, zlotawy <zlot...@gmail.com> wrote:
> Witam,
> stworzyłem sobie widok materialny z klauzula query rewrite:
>
> create materialized view xxx_snapshot
> ENABLE QUERY REWRITE as
> select cabc.branch_code,cabc.ccy_code, ccp.ccy, ccp.cash_position,
> new_pos.l_amt
> from CYVWS_ALL_BR_CCYS cabc, CYTBS_CASH_POSITION ccp, (SELECT
> ccy,sum(decode(drcr,'C',-amount,amount)) l_amt
>                                                              from
> CYVW_CASH_POSITION
>                                                              group
> by ccy) new_pos
> where cabc.ccy_code = ccp.ccy(+)
> and cabc.ccy_code = new_pos.ccy(+);
>
> parametr QUERY REWRITE w bazie ustawiony jest na TRUE.
>
> W przypadku gdy wywolam
>
> select * from xxx_snapshot wynik co oczywiste mam
> momentalnie.
>
> Natomiast wywolanie
> select cabc.branch_code,cabc.ccy_code, ccp.ccy, ccp.cash_position,
> new_pos.l_amt
> from CYVWS_ALL_BR_CCYS cabc, CYTBS_CASH_POSITION ccp, (SELECT
> ccy,sum(decode(drcr,'C',-amount,amount)) l_amt
>                                                              from
> CYVW_CASH_POSITION
>                                                              group
> by ccy) new_pos
> where cabc.ccy_code = ccp.ccy(+)
> and cabc.ccy_code = new_pos.ccy(+);
>
> czyli kodu wzietego zywcem z definicji snapshota, powoduje, ze
> obliczenia wykonuja sie na nowo. Plan zapytania takze nie wyswietla,
> ze system korzysta ze snapshota.
>
> Czy ktos ma propozycje co robie nie tak?
>
> Pozdrawiam
> Wojtek

Wojtek,
>>Czy ktos ma propozycje co robie nie tak?<<
Wywolanie SELECT nawet identycznego z VIEW (MATERIALIZED) nie
zapewnia automatycznie, ze Oracle uzyje tego samego planu, co do VIEW.
Musisz wywolac SELECT... FROM xxx_snapshot
HTH
Thomas
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From: Thomas Olszewicki <ThomasO@cpas.com>
Newsgroups: pl.comp.bazy-danych
Subject: Re: Oracle 10 - Materialny widok - Query Rewrite
Date: Wed, 24 Jun 2009 06:19:39 -0700 (PDT)
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