Re: How to use read uncommitted transaction level and set update order - Mailing list pgsql-general

From Jaime Casanova
Subject Re: How to use read uncommitted transaction level and set update order
Date
Msg-id 3073cc9b0912191335h49f884b7he3c0459872ce9968@mail.gmail.com
Whole thread Raw
In response to How to use read uncommitted transaction level and set update order  ("Andrus" <kobruleht2@hot.ee>)
List pgsql-general
2009/12/19 Andrus <kobruleht2@hot.ee>:
>
> set transaction isolation level read uncommitted;

the "isolation level" is for specifying what rows are visible no for columns.
besides, postgres doesn't implement "read uncommitted"

> update test1 set a=4, b=a ;
>
> b value is 1 but must be 4.

no. b value "must be" 1, you want it to be 4...
in an update the columns always hold the old value until the statement
is finished, the only way i can think for doing this is with a trigger

--
Atentamente,
Jaime Casanova
Soporte y capacitación de PostgreSQL
Asesoría y desarrollo de sistemas
Guayaquil - Ecuador
Cel. +59387171157

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