Re: AW: BLERe: AW: AW: relation ### modified while in use

From: Philip Warner <pjw(at)rhyme(dot)com(dot)au>
To: Hiroshi Inoue <Inoue(at)tpf(dot)co(dot)jp>, Zeugswetter Andreas SB <ZeugswetterA(at)wien(dot)spardat(dot)at>
Cc: "'Tom Lane'" <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: AW: BLERe: AW: AW: relation ### modified while in use
Date: 2000-10-25 06:47:40
Message-ID: 3.0.5.32.20001025164740.02b237d0@mail.rhyme.com.au
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At 18:31 24/10/00 +0900, Hiroshi Inoue wrote:
>
>
>Zeugswetter Andreas SB wrote:
>
>> > > > Are there many applications which have many SELECT statements(without
>> > > > FOR UPDATE) in one tx ?
>> > >
>> > > Why not ?
>> > >
>> > It seems to me that multiple SELECT statements in a tx has little
>> > meaning unless the tx is executed in SERIALIZABLE isolation level.
>>
>> E.g. a table is accessed multiple times to select different data
>> in an inner application loop. No need for serializable here.
>>
>
>And seems no need to execute in one tx.
>Hmm,we seems to be able to call a cleanup procedure
>internally which is equivalent to 'commit' after each
>consecutive read-only statement. Is it a problem ?

I have not followed the entire thread, but if you are in a serializable OR
repeatable-read transaction, I would think that read-only statements will
need to keep some kind of lock on the rows they read (or the table).

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