| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)2ndquadrant(dot)com> |
| Cc: | Claudio Freire <klaussfreire(at)gmail(dot)com>, Marco Nenciarini <marco(dot)nenciarini(at)2ndquadrant(dot)it>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Gabriele Bartolini <gabriele(dot)bartolini(at)2ndquadrant(dot)it>, desmodemone <desmodemone(at)gmail(dot)com>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Proposal: Incremental Backup |
| Date: | 2014-08-12 15:58:36 |
| Message-ID: | CA+TgmoaUbPvKO66pBsThrijtGcVi5uo6OcfXQPFUyGs8vdmijA@mail.gmail.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
On Tue, Aug 12, 2014 at 10:30 AM, Andres Freund <andres(at)2ndquadrant(dot)com> wrote:
>> Still not safe. Checksum collisions do happen, especially in big data sets.
>
> If you use an appropriate algorithm for appropriate amounts of data
> that's not a relevant concern. You can easily do different checksums for
> every 1GB segment of data. If you do it right the likelihood of
> conflicts doing that is so low it doesn't matter at all.
True, but if you use LSNs the likelihood is 0. Comparing the LSN is
also most likely a heck of a lot faster than checksumming the entire
page.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Andres Freund | 2014-08-12 16:03:35 | Re: [RFC] Should smgrtruncate() avoid sending sinval message for temp relations |
| Previous Message | Robert Haas | 2014-08-12 15:56:41 | Re: [RFC] Should smgrtruncate() avoid sending sinval message for temp relations |