Re: [HACKERS] Detach/attach table and index data files from one cluster to another

2013-04-13 Thread Sameer Thakur
On Fri, Apr 12, 2013 at 9:52 PM, Andres Freund and...@2ndquadrant.comwrote: On 2013-04-12 12:14:24 -0400, Tom Lane wrote: Andrew Dunstan and...@dunslane.net writes: On 04/12/2013 10:15 AM, Tom Lane wrote: There's 0 chance of making that work, because the two databases wouldn't have

Re: [HACKERS] Enabling Checksums

2013-04-13 Thread Simon Riggs
On 12 April 2013 23:21, Ants Aasma a...@cybertec.at wrote: In general, we have more flexibility with WAL because there is no upgrade issue. It would be nice to share code with the data page checksum algorithm; but really we should just use whatever offers the best trade-off in terms of

Re: [HACKERS] Process title for autovac

2013-04-13 Thread Peter Eisentraut
On Sat, 2013-04-06 at 13:20 -0700, Jeff Janes wrote: I've often wanted to know what the autovacuum worker was doing. The process title seems like the best place to get this information, but the process title tells me what database it is in, but not what table it is working on. Because the

Re: [HACKERS] PROPOSAL: tracking aggregated numbers from pg_stat_database

2013-04-13 Thread Peter Eisentraut
On Sat, 2013-04-06 at 21:51 +0200, Tomas Vondra wrote: This more or less works in stable environments, but once you start dropping databases (think of hosting with shared DB server) it gets unusable because after DROP DATABASE the database suddenly disappears from the sum. Therefore I do

Re: [HACKERS] Enabling Checksums

2013-04-13 Thread Bruce Momjian
On Fri, Apr 12, 2013 at 02:38:27PM -0700, Jeff Davis wrote: In general, we have more flexibility with WAL because there is no upgrade issue. It would be nice to share code with the data page checksum algorithm; but really we should just use whatever offers the best trade-off in terms of

Re: [HACKERS] Enabling Checksums

2013-04-13 Thread Andres Freund
On 2013-04-13 09:14:26 -0400, Bruce Momjian wrote: On Fri, Apr 12, 2013 at 02:38:27PM -0700, Jeff Davis wrote: In general, we have more flexibility with WAL because there is no upgrade issue. It would be nice to share code with the data page checksum algorithm; but really we should just use

Re: [HACKERS] Enabling Checksums

2013-04-13 Thread Tom Lane
Andres Freund and...@2ndquadrant.com writes: On 2013-04-13 09:14:26 -0400, Bruce Momjian wrote: As I understand it, SIMD is just a CPU-optimized method for producing a CRC checksum. Is that right? Does it produce the same result as a non-CPU-optimized CRC calculation? No we are talking

Re: [HACKERS] Enabling Checksums

2013-04-13 Thread Andres Freund
On 2013-04-13 10:58:53 -0400, Tom Lane wrote: Andres Freund and...@2ndquadrant.com writes: On 2013-04-13 09:14:26 -0400, Bruce Momjian wrote: As I understand it, SIMD is just a CPU-optimized method for producing a CRC checksum. Is that right? Does it produce the same result as a

Re: [HACKERS] Enabling Checksums

2013-04-13 Thread Ants Aasma
On Sat, Apr 13, 2013 at 5:58 PM, Tom Lane t...@sss.pgh.pa.us wrote: Andres Freund and...@2ndquadrant.com writes: On 2013-04-13 09:14:26 -0400, Bruce Momjian wrote: As I understand it, SIMD is just a CPU-optimized method for producing a CRC checksum. Is that right? Does it produce the same

Re: [HACKERS] Enabling Checksums

2013-04-13 Thread Andres Freund
On 2013-04-13 18:14:28 +0300, Ants Aasma wrote: On Sat, Apr 13, 2013 at 5:58 PM, Tom Lane t...@sss.pgh.pa.us wrote: Andres Freund and...@2ndquadrant.com writes: On 2013-04-13 09:14:26 -0400, Bruce Momjian wrote: As I understand it, SIMD is just a CPU-optimized method for producing a CRC

Re: [HACKERS] PROPOSAL: tracking aggregated numbers from pg_stat_database

2013-04-13 Thread Tomas Vondra
On 13.4.2013 15:01, Peter Eisentraut wrote: On Sat, 2013-04-06 at 21:51 +0200, Tomas Vondra wrote: This more or less works in stable environments, but once you start dropping databases (think of hosting with shared DB server) it gets unusable because after DROP DATABASE the database suddenly

Re: [HACKERS] Enabling Checksums

2013-04-13 Thread Ants Aasma
On Sat, Apr 13, 2013 at 6:26 PM, Andres Freund and...@2ndquadrant.com wrote: All in all I would say that the performance is worth the loss in detection capability as we are not talking about using the checksum to prove correctness. Is it actually a loss compared to our 16bit flavor of crc32

Re: [HACKERS] Process title for autovac

2013-04-13 Thread Jeff Janes
On Sat, Apr 13, 2013 at 5:56 AM, Peter Eisentraut pete...@gmx.net wrote: On Sat, 2013-04-06 at 13:20 -0700, Jeff Janes wrote: I've often wanted to know what the autovacuum worker was doing. The process title seems like the best place to get this information, but the process title tells me

Re: [HACKERS] Enabling Checksums

2013-04-13 Thread Bruce Momjian
On Sat, Apr 13, 2013 at 06:14:28PM +0300, Ants Aasma wrote: CRCs are known to be good for that sort of thing; it's what they were designed for. I'd like to see some evidence that any substitute algorithm has similar properties. Without that, I'm going to vote against this idea. Sorry

Re: [HACKERS] PROPOSAL: tracking aggregated numbers from pg_stat_database

2013-04-13 Thread Alvaro Herrera
Tomas Vondra wrote: On 13.4.2013 15:01, Peter Eisentraut wrote: long-term analysis? Maybe you could even use event triggers to have DROP DATABASE do that automatically. I don't think event triggers are a good solution, although I'm wondering how that's supposed to work. It doesn't,

Re: [HACKERS] Nearing beta?

2013-04-13 Thread Peter Eisentraut
On Thu, 2013-04-11 at 12:22 -0400, Tom Lane wrote: We went around on whether we liked this or not, but it seemed to me that the discussion came out at the same place Peter had submitted to start with. I don't know why he's not committed it, but I have no objection to him doing so, as long as