| From: | Ravi Krishna <rkrishna(at)vivaldi(dot)net> |
|---|---|
| To: | pgsql-general(at)lists(dot)postgresql(dot)org |
| Subject: | Re: Doubt in mvcc |
| Date: | 2020-07-13 09:51:19 |
| Message-ID: | 81860c68-0d85-facd-01a9-8db1a72f933a@vivaldi.net |
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| Lists: | pgsql-general |
On 7/13/2020 4:52 AM, Rama Krishnan wrote:
> For example, two transactions are going to increase the amount on the
> same account by $100 . The first transaction reads the current value
> ($1000) and then the second transaction reads the same value. The first
> transaction increases the amount (this gives $1100) and writes this
> value. The second transaction acts the same way: it gets the same $1100
> and writes this value. As a result, the customer lost $100.
>
>
> Will u please provide more details
>
>
> Serialize is the solution to this issue.
MVCC applies to read and write situation. Readers do not block writers
and writers do not block read. The example you mentioned above is writer
vs writer and MVCC (both Oracle and PG) is not applicable.
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