Re: Selects query inside function must read commited data

In the v7.3 docs:

http://www.postgresql.org/docs/7.3/interactive/transaction-iso.html#XACT-READ-COMMITTED

/Read Committed/ is the default isolation level in PostgreSQL. When a
transaction runs on this isolation level, a SELECT query sees only data
committed before the query began; it never sees either uncommitted data
or changes committed during query execution by concurrent transactions.
(However, the SELECT does see the effects of previous updates executed
within its own transaction, even though they are not yet committed.) In
effect, a SELECT query sees a snapshot of the database as of the instant
that that query begins to run. Notice that two successive SELECTs can
see different data, even though they are within a single transaction, if
other transactions commit changes during execution of the first SELECT.

Andrew

V i s h a l Kashyap @ [Sai Hertz And Control Systems] wrote:

> Dear Oliver Elphick ,
>
>>>If I am not wrong PostgreSQL select statements works on committed data
>>>thus the new
>>>inserted data at #3 must not be available to sai_func_b() till #5
>>>
>>>
>>
>>No. All operations by a single transaction are visible inside the
>>transaction. Therefore an encapsulated function can see anything already
>>done in the whole transaction. A function must be entirely inside a
>>transaction and cannot start a transaction, so there can never be any
>>problem about this.
>>
>>
> Loads of thanks for the kind reply .
> Would be greatefull if you kindly post some links/refrences to support
> your answer for the said.
> Thanks one again .
>
>
>--
>Regards,
>Vishal Kashyap
>
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