From: | Kevin Grittner <kgrittn(at)gmail(dot)com> |
---|---|
To: | Tatsuo Ishii <ishii(at)postgresql(dot)org> |
Cc: | samokhvalov(at)gmail(dot)com, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: "Strong sides of MySQL" talk from PgDay16Russia, translated |
Date: | 2016-07-29 13:17:02 |
Message-ID: | CACjxUsPTEq=L1M9=cJCaQ3hHthjpkjdAdBVTYcTmvqEWqY5TJQ@mail.gmail.com |
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On Thu, Jul 28, 2016 at 8:39 PM, Tatsuo Ishii <ishii(at)postgresql(dot)org> wrote:
> BTW, is there any opposite information, i.e. showing the
> limitation of MySQL comparing with PostgreSQL?
I'm not aware of a general list on the topic, but in reviewing
academic papers regarding transaction isolation I did find (and
confirm) that MySQL InnoDB relaxes the "strict" aspect of the
Strict 2 Phase Locking they use for implementing serializable
transactions. "For performance reasons" they drop the locks
acquired during the transaction *before* ensuring crash/recovery
persistence. This is more-or-less equivalent to always running
with synchronous_commit = off as well as allowing a small window
for serialization anomalies in corner cases. The PostgreSQL
synchronous_commit option allows a similar performance benefit
(where the trade-off is deemed justified) without risking data
integrity in the same way.
--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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