| From: | Csaba Nagy <nagy(at)ecircle-ag(dot)com> |
|---|---|
| To: | Hannu Krosing <hannu(at)2ndQuadrant(dot)com> |
| Cc: | Simon Riggs <simon(at)2ndQuadrant(dot)com>, Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, Gregory Stark <stark(at)enterprisedb(dot)com>, Richard Huxton <dev(at)archonet(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Transaction Snapshots and Hot Standby |
| Date: | 2008-09-12 11:54:54 |
| Message-ID: | 1221220494.17270.155.camel@PCD12478 |
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| Lists: | pgsql-hackers |
> I think that enabling long-running queries this way is both
> low-hanging
> fruit (or at least medium-height-hanging ;) ) and also consistent to
> PostgreSQL philosophy of not replication effort. As an example we trust
> OS's file system cache and don't try to write our own.
I have again questions (unfortunately I only have questions usually):
* how will the buffers keep 2 different versions of the same page ?
* how will you handle the creation of snapshots ? I guess there's no portable and universal API for that (just guessing), or there is some POSIX thing which is supported or not by the specific FS ? So if the FS is not supporting it, you skip the snapshot step ? And if there's no universal API, will it be handled by plugins providing a specified API for snapshotting the FS ?
I hope my continuous questioning is not too annoying...
Cheers,
Csaba.
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