Isolation level in a function

Started by Bart Goldaabout 20 years ago2 messagesgeneral
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#1Bart Golda
e9syuk002@sneakemail.com

Hello, this is my first post, please don't shoot...

I was just experimenting with transactions (PG 8.1), and there is
something which puzzles me. If i write 'SET TRANSACTION ISOLATION LEVEL
SERIALIZABLE;' in my function, it breaks. Error informs me, that it was
executed after some query, while it is a first command in the function
after declares and begin!

However, it seems to work perfectly well if I change in the same place
the system variable, responsible for the transaction level. I used
set_config, if I remember well. The function is only for a DBA task, so
it seems to be all right to use set_config, isn't it?

And my questions are:
1) Why in the first case it is not possible? Is it an error or am I
just doing something wrong? Should have set something before?
2) Are there any downsides of the mentioned solution (changing
transaction_isolation value), except of the fact that it is an
administration command and should not be used :)?

Thanks,

_-_-_-_
Bart Golda

#2Bruno Wolff III
bruno@wolff.to
In reply to: Bart Golda (#1)
Re: Isolation level in a function

On Thu, Jan 19, 2006 at 02:05:41 -0800,
bgolda <e9syuk002@sneakemail.com> wrote:

Hello, this is my first post, please don't shoot...

I was just experimenting with transactions (PG 8.1), and there is
something which puzzles me. If i write 'SET TRANSACTION ISOLATION LEVEL
SERIALIZABLE;' in my function, it breaks. Error informs me, that it was
executed after some query, while it is a first command in the function
after declares and begin!

Because there is already a transaction which the function is executing in
and for which a query has been started (e.g. the one that calls the function).

Show quoted text

However, it seems to work perfectly well if I change in the same place
the system variable, responsible for the transaction level. I used
set_config, if I remember well. The function is only for a DBA task, so
it seems to be all right to use set_config, isn't it?

And my questions are:
1) Why in the first case it is not possible? Is it an error or am I
just doing something wrong? Should have set something before?
2) Are there any downsides of the mentioned solution (changing
transaction_isolation value), except of the fact that it is an
administration command and should not be used :)?

Thanks,

_-_-_-_
Bart Golda

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