| From: | Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> |
|---|---|
| To: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
| Cc: | Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>, Robert Haas <robertmhaas(at)gmail(dot)com>, Greg Sabino Mullane <greg(at)endpoint(dot)com>, Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Overhead cost of Serializable Snapshot Isolation |
| Date: | 2011-10-12 05:34:22 |
| Message-ID: | 4E9526DE.6040706@enterprisedb.com |
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| Thread: | |
| Lists: | pgsql-hackers |
On 11.10.2011 23:21, Simon Riggs wrote:
> If the normal default_transaction_isolation = read committed and all
> transactions that require serializable are explicitly marked in the
> application then there is no way to turn off SSI without altering the
> application. That is not acceptable, since it causes changes in
> application behaviour and possibly also performance issues.
I don't get that. If all the transactions that require serializability
are marked as such, why would you disable SSI for them? That would just
break the application, since the transactions would no longer be
serializable.
If they don't actually need serializability, but repeatable read is
enough, then mark them that way.
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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