| From: | Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at> |
|---|---|
| To: | Rama Krishnan <raghuldrag(at)gmail(dot)com>, pgsql-general(at)postgresql(dot)org |
| Subject: | Re: Doubt in mvcc |
| Date: | 2020-07-14 06:50:40 |
| Message-ID: | c754e62e3b88aeef133ef9816227bec80f335230.camel@cybertec.at |
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| Lists: | pgsql-general |
On Mon, 2020-07-13 at 13:01 +0530, Rama Krishnan wrote:
> I m preparing for interview one of the recruiter asked me mvcc drawbacks as i told due
> to mvcc it use more space and need to perform maintenance activity.
Yes. Generally speaking, you have to pay a price for keeping old versions of the
data around, no matter how you implement it.
> Another one is the same data causes an update conflict because two different transactions
> can update the same version of the row.
> he told its wrong, kindly tell me will you please tell me its correct or wrong?
There is always a certain version (the latest) that can be updated, so this is
the same no matter if you have MVCC or not: if two sessions want to update the same
row, one has to wait until the other is done.
Yours,
Laurenz Albe
--
Cybertec | https://www.cybertec-postgresql.com
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