Re: An example needed for Serializable conflict... - Mailing list pgsql-general

From Andres Freund
Subject Re: An example needed for Serializable conflict...
Date
Msg-id 200907071243.58671.andres@anarazel.de
Whole thread Raw
In response to Re: An example needed for Serializable conflict...  (durumdara <durumdara@gmail.com>)
List pgsql-general
Hi durumdara,

On Tuesday 07 July 2009 12:10:52 durumdara wrote:
> Another question if I use only "SELECTS" can I get some Serialization
> Error?
No.

> For example:
> I need a report tool that can show the actual state of the business.
> Because of I use value-dependent logic, I MUST use consistent state to
> preserve the equality of many values (sums, counts, etc.).
> So some (Read Committer) threads are update/delete/insert (sum modify)
> rows, but this report tool only READ the tables, and only works for temp
> tables.
> Can I get some S. error from this transaction?
> Or can I get some error from modifier threads if this (serializer
> report) thread actually read the rows that they are want to modify?
You can get errors between the writers but not between a writer and a reader.

It probably would be a good idea to read the documentation about mvcc (
http://www.postgresql.org/docs/current/static/mvcc.html) to understand the
possibilities/constraints better.

Andres

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