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Your wish is my command sir. I am hard of hearing so I try to transcribe talks. This one is more abbreviated than my last one. Secrets of Postgres Performance

Your wish is my command sir. I am hard of hearing so I try to transcribe talks. This one is more abbreviated than my last one. Secrets of Postgres Performance Measure Everything Before and After Do not do Dumb Things Cache Everything Watch your query counts Tuning Parameters shared_buffers: set to 25% of available ram, move up/down 5% to find sweet spot effective_cache_size: planning hint that tells PG how much RAM it can expect for OS disk cache work_mem: per process amount of ORDER BY space Other Parameters wal_buffers: Set to 16MB and forget it checkpoint_segments: Increase to at least 10 maintenance_work_mem: 50MB for every GB of RAM synchronous_commit: turn off with data loss risks Disks. Lots of disks. Not all disks are created equal. Faster disks make a huge difference. Configuration of disks matters a lot. RAID-5 is bad. RAID-1+0 is good. Separate out the WAL onto its own disk. Can 4x write performance. Worry about CPU after your disk/RAID/filesystem configurations are more or less optimal. Use pgbouncer to pool connections Tablespaces Consider putting archive or legacy data onto slower drives/volumes Separate your data and indices onto different volumes if possible This applies even on SANs Best of both worlds with Rackspace and Cloud Connect EBS volumes and Software RAID is best but scary on AWS. Choice of filesystem matters. No journaled filesystems for your WAL, it is a journal. Use XFS for maximum performance. USE noatime! Avoid queries in loops. Count() is slow

tobtoh 15y ago
Awesome - thanks! And look at that - a 35 minute video is compressed into 1 minute of reading and I bet, thanks to the summary, I obtained 75% of the relevant info that I would have got if I had watched the video in it's entirety.
- alnayyir 15y ago
  You're welcome, hope it helped. I really despise non-textual media.
  - zobzu 15y ago
    I can hear and see perfectly. And I love concise text data. Long videos, audio or long documents with a lot of blabla sucks. Thank you.
SkyMarshal 15y ago
Man you are awesome, thank you. I hate video for these kinds of things, it's like watching paint dry when I could have speed-read through a transcript in a tenth the time it takes to watch a video. I don't know if I'm an edge case here, but if not there might be some kind of opportunity there.
- alnayyir 15y ago
  That occurred to me earlier. There's a lot of people like us (I think) who really just want to accumulate as much "80/20" information as possible and don't want multi-media. Call it, "The wiki for getting to the fucking point".
  - aaronbrethorst 15y ago
    Tragically, gettothefuckingpoint.com is taken by a squatter. What a pity.
  - gojomo 15y ago
    Workin' on it.
- plasma 15y ago
  I also hate videos; they are too slow to get to the point. With text, at least I can speed read and ignore stuff that is not important to me.
bmurphy 15y ago
Very nice, thank you. Mostly all of this is good advice and correlates nicely with my experience. One thing though: "EBS volumes and Software RAID is best but scary on AWS" I've managed an EBS RAID10 database for a few years now. I wouldn't touch this with a 10 foot pole. Do yourself a favor, set up an m1.xlarge (or bigger) instance, put the ephemeral drives in a RAID0 and mirror across multiple machines using hot-standby, slony, londiste, or some other tool. You'll be much happier, your system will perform much better, and you'll have a failover strategy in place.
- jdunck 15y ago
  And what happens when the AZ goes down? Don't you lose data then? Or do you mean multiple machines across AZ/region?
  - joevandyk 15y ago
    You'll want the mirror in a different AZ. Or you could also put it in a different region. Use Wal-E to push wal logs to s3.
    - bmurphy 15y ago
      Absolutely. You should always be spreading your data across multiple availability zones and where feasible across multiple data centers and S3 is a great place to store your wal logs. We do the same thing.
- sandGorgon 15y ago
  I dont understand this - is there a difference between an explicitly allocated EBS volume and the ephemeral volumes of an EBS-backed instance ? Or are you focusing on the RAID10 part - but then everywhere RAID10 is touted to be the best RAID solution (right balance between performance and safety)
  - joevandyk 15y ago
    Yes, there is a difference between EBS volumes and ephemeral volumes of an EBS-backed instance.

tobtoh 15y ago

Awesome - thanks! And look at that - a 35 minute video is compressed into 1 minute of reading and I bet, thanks to the summary, I obtained 75% of the relevant info that I would have got if I had watched the video in it's entirety.

alnayyir 15y ago
You're welcome, hope it helped. I really despise non-textual media.
- zobzu 15y ago
  I can hear and see perfectly. And I love concise text data. Long videos, audio or long documents with a lot of blabla sucks. Thank you.

SkyMarshal 15y ago

Man you are awesome, thank you. I hate video for these kinds of things, it's like watching paint dry when I could have speed-read through a transcript in a tenth the time it takes to watch a video. I don't know if I'm an edge case here, but if not there might be some kind of opportunity there.

alnayyir 15y ago
That occurred to me earlier. There's a lot of people like us (I think) who really just want to accumulate as much "80/20" information as possible and don't want multi-media. Call it, "The wiki for getting to the fucking point".
- aaronbrethorst 15y ago
  Tragically, gettothefuckingpoint.com is taken by a squatter. What a pity.
- gojomo 15y ago
  Workin' on it.
plasma 15y ago
I also hate videos; they are too slow to get to the point. With text, at least I can speed read and ignore stuff that is not important to me.

bmurphy 15y ago

Very nice, thank you. Mostly all of this is good advice and correlates nicely with my experience. One thing though: "EBS volumes and Software RAID is best but scary on AWS" I've managed an EBS RAID10 database for a few years now. I wouldn't touch this with a 10 foot pole. Do yourself a favor, set up an m1.xlarge (or bigger) instance, put the ephemeral drives in a RAID0 and mirror across multiple machines using hot-standby, slony, londiste, or some other tool. You'll be much happier, your system will perform much better, and you'll have a failover strategy in place.

jdunck 15y ago
And what happens when the AZ goes down? Don't you lose data then? Or do you mean multiple machines across AZ/region?
- joevandyk 15y ago
  You'll want the mirror in a different AZ. Or you could also put it in a different region. Use Wal-E to push wal logs to s3.
  - bmurphy 15y ago
    Absolutely. You should always be spreading your data across multiple availability zones and where feasible across multiple data centers and S3 is a great place to store your wal logs. We do the same thing.
sandGorgon 15y ago
I dont understand this - is there a difference between an explicitly allocated EBS volume and the ephemeral volumes of an EBS-backed instance ? Or are you focusing on the RAID10 part - but then everywhere RAID10 is touted to be the best RAID solution (right balance between performance and safety)
- joevandyk 15y ago
  Yes, there is a difference between EBS volumes and ephemeral volumes of an EBS-backed instance.