Re: [PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
Date: Sun, 12 Oct 2003 13:30:45 -0700 From: Josh Berkus [EMAIL PROTECTED] To: Nick Barr [EMAIL PROTECTED] Cc: [EMAIL PROTECTED] Subject: Re: go for a script! / ex: PostgreSQL vs. MySQL Message-ID: [EMAIL PROTECTED] This would be parameters such as the block size and a few other compile time parameters. If we can get to some of these read-only parameters than that would make this step easier, certainly for the new recruits amongst us. Actually, from my perspective, we shouldn't bother with this; if an admin knows enough to set an alternate blaock size for PG, then they know enough to tweak the Conf file by hand. I think we should just issue a warning that this script: 1) does not work for anyone who is using non-default block sizes, There was some talk, either on this list or freebsd-performance about setting the default block size for PostgreSQL running on FreeBSD to be 16k because of performance reasons. That is: *default* for the port, user is not asked. So an automagical method to scale non-default block sizes is a very needed thing. 2) may not work well for anyone using unusual locales, optimization flags, or other non-default compile options except for language interfaces. Depends on what you consider 'unusual'? I hope not things like iso8859-x (or, to be exact, European languages) :) -- Logic is a systematic method of coming to the wrong conclusion with confidence. ---(end of broadcast)--- TIP 7: don't forget to increase your free space map settings
Re: [PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
Ivan, There was some talk, either on this list or freebsd-performance about setting the default block size for PostgreSQL running on FreeBSD to be 16k because of performance reasons. That is: *default* for the port, user is not asked. So an automagical method to scale non-default block sizes is a very needed thing. Hmmm ... possibly. My concern is that if someone uses a very non-default value, such as 256K, then they are probably better off doing their own tuning because they've got an unusual system. However, we could easily limit it to the range of 4K to 32K. Of course, since there's no GUC var, we'd have to ask the user to confirm their block size. I'm reluctant to take this approach because if the user gets it wrong, then the settings will be *way* off ... and possibly cause PostgreSQL to be unrunnable or have out of memory crashes. Unless there's a way to find it in the compiled source? 2) may not work well for anyone using unusual locales, optimization flags, or other non-default compile options except for language interfaces. Depends on what you consider 'unusual'? I hope not things like iso8859-x (or, to be exact, European languages) :) On second thought, I'm not sure what an unusual locale would be. Scratch that. -- Josh Berkus Aglio Database Solutions San Francisco ---(end of broadcast)--- TIP 8: explain analyze is your friend
Re: [PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
Josh Berkus [EMAIL PROTECTED] writes: Unless there's a way to find it in the compiled source? See pg_controldata. regards, tom lane ---(end of broadcast)--- TIP 8: explain analyze is your friend
Re: [PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
This would be parameters such as the block size and a few other compile time parameters. If we can get to some of these read-only parameters than that would make this step easier, certainly for the new recruits amongst us. Actually, from my perspective, we shouldn't bother with this; if an admin knows enough to set an alternate blaock size for PG, then they know enough to tweak the Conf file by hand. I think we should just issue a warning that this script: 1) does not work for anyone who is using non-default block sizes, There was some talk, either on this list or freebsd-performance about setting the default block size for PostgreSQL running on FreeBSD to be 16k because of performance reasons. That is: *default* for the port, user is not asked. Real quick, this isn't true, the block size is tunable, but does not change the default. You can set PGBLOCKSIZE to the values 16K or 32K to change the block size, but the default remains 8K. http://lists.freebsd.org/pipermail/freebsd-database/2003-October/000111.html -sc -- Sean Chittenden ---(end of broadcast)--- TIP 4: Don't 'kill -9' the postmaster
Re: [PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
SC == Sean Chittenden [EMAIL PROTECTED] writes: echo effective_cache_size = $((`sysctl -n vfs.hibufspace` / 8192)) I've used it for my dedicated servers. Is this calculation correct? SC Yes, or it's real close at least. vfs.hibufspace is the amount of SC kernel space that's used for caching IO operations (minus the I'm just curious if anyone has a tip to increase the amount of memory FreeBSD will use for the cache? It appears to me that even on my 2Gb box, lots of memory is 'free' that could be used for the cache (bumping up shared buffers is another option...) yet the disk is being highly utilized according to systat. ---(end of broadcast)--- TIP 4: Don't 'kill -9' the postmaster
Re: [PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
On Monday 13 October 2003 19:34, Vivek Khera wrote: SC == Sean Chittenden [EMAIL PROTECTED] writes: echo effective_cache_size = $((`sysctl -n vfs.hibufspace` / 8192)) I've used it for my dedicated servers. Is this calculation correct? SC Yes, or it's real close at least. vfs.hibufspace is the amount of SC kernel space that's used for caching IO operations (minus the I'm just curious if anyone has a tip to increase the amount of memory FreeBSD will use for the cache? It appears to me that even on my 2Gb box, lots of memory is 'free' that could be used for the cache (bumping up shared buffers is another option...) yet the disk is being highly utilized according to systat. Is this of any help?..reverse video sucks though.. especially spec'ed person like me.. http://unix.derkeiler.com/Mailing-Lists/FreeBSD/performance/2003-07/0073.html Shridhar ---(end of broadcast)--- TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]
Re: [PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
echo effective_cache_size = $((`sysctl -n vfs.hibufspace` / 8192)) I've used it for my dedicated servers. Is this calculation correct? SC Yes, or it's real close at least. vfs.hibufspace is the amount of SC kernel space that's used for caching IO operations (minus the I'm just curious if anyone has a tip to increase the amount of memory FreeBSD will use for the cache? Recompile your kernel with BKVASIZE set to 4 times its current value and double your nbuf size. According to Bruce Evans: Actually there is a way: the vfs_maxbufspace gives the amount of space reserved for buffer kva (= nbuf * BKVASIZE). nbuf is easy to recover from this, and the buffer kva space may be what is wanted anyway. [snip] I've never found setting nbuf useful, however. I want most parametrized sizes including nbuf to scale with resource sizes, and it's only with RAM sizes of similar sizes to the total virtual address size that its hard to get things to fit. I haven't hit this problem myself since my largest machine has only 1GB. I use an nbuf of something like twice the default one, and a BKVASIZE of 4 times the default. vfs.maxbufspace ends up at 445MB on the machine with 1GB, so it is maxed out now. YMMV. -sc -- Sean Chittenden ---(end of broadcast)--- TIP 6: Have you searched our list archives? http://archives.postgresql.org
Re: [PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
PostgreSQL requires some more shared memory to cache some tables, x Mb, do you want to increase your OS kernel parameters? Tweak shmmax and shmmall Note that this still requires a kernel recompile on FreeBSD :( Not our fault, now is it? This would mean that we wouldn't be able to script for FreeBSD. Bug the FreeBSD developers. And if you do so, you're going to hear that shm* is an antiquated interface that's dated, slow, inefficient and shouldn't be used. :) Every few months one of the uber core BSD hackers threatens to rewrite that part of PG because high up in the BSD camp, it's common belief that shm* is a source of performance loss for PostgreSQL. One of these days it'll happen, probably with mmap() mmap()'ing MAP_SHARED files stored in a $PGDATA/data/shared dir as mmap() is by far and away the fastest shared memory mechanism and certainly is very widely deployed (I would be surprised if any of the supported PG platforms didn't have mmap()). -sc -- Sean Chittenden ---(end of broadcast)--- TIP 2: you can get off all lists at once with the unregister command (send unregister YourEmailAddressHere to [EMAIL PROTECTED])
Re: [PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
JB == Josh Berkus [EMAIL PROTECTED] writes: JB Chris, PostgreSQL requires some more shared memory to cache some tables, x Mb, do you want to increase your OS kernel parameters? Tweak shmmax and shmmall Note that this still requires a kernel recompile on FreeBSD :( JB Not our fault, now is it? This would mean that we wouldn't be JB able to script for FreeBSD. Bug the FreeBSD developers. I read it on the net so it must be true applies here. You /can/ set these values via sysctl calls. -- =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Vivek Khera, Ph.D.Khera Communications, Inc. Internet: [EMAIL PROTECTED] Rockville, MD +1-240-453-8497 AIM: vivekkhera Y!: vivek_khera http://www.khera.org/~vivek/ ---(end of broadcast)--- TIP 9: the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
Re: [PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
CK == Christopher Kings-Lynne [EMAIL PROTECTED] writes: If shmmax and shmmall are too small, then: PostgreSQL requires some more shared memory to cache some tables, x Mb, do you want to increase your OS kernel parameters? Tweak shmmax and shmmall CK Note that this still requires a kernel recompile on FreeBSD :( According to whom? sysctl is your friend. Some sysctl settings may require reboot, but I don't think the SHM ones do. -- =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Vivek Khera, Ph.D.Khera Communications, Inc. Internet: [EMAIL PROTECTED] Rockville, MD +1-240-453-8497 AIM: vivekkhera Y!: vivek_khera http://www.khera.org/~vivek/ ---(end of broadcast)--- TIP 4: Don't 'kill -9' the postmaster
Re: [PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
Centuries ago, Nostradamus foresaw when [EMAIL PROTECTED] (Vivek Khera) would write: JB == Josh Berkus [EMAIL PROTECTED] writes: JB Chris, PostgreSQL requires some more shared memory to cache some tables, x Mb, do you want to increase your OS kernel parameters? Tweak shmmax and shmmall Note that this still requires a kernel recompile on FreeBSD :( JB Not our fault, now is it? This would mean that we wouldn't be JB able to script for FreeBSD. Bug the FreeBSD developers. I read it on the net so it must be true applies here. You /can/ set these values via sysctl calls. Yes, indeed, sysctl can tweak these values fairly adequately. Now, numbers of semaphors are not as readily tweaked; I wound up limited, the other day, when I tried setting values for... kern.ipc.semmns kern.ipc.semmni -- let name=cbbrowne and tld=ntlug.org in String.concat @ [name;tld];; http://www.ntlug.org/~cbbrowne/x.html So, when you typed in the date, it exploded into a sheet of blue flame and burned the entire admin wing to the ground? Yes, that's a known bug. We'll be fixing it in the next release. Until then, try not to use European date format, and keep an extinguisher handy. -- [EMAIL PROTECTED] (Tequila Rapide) ---(end of broadcast)--- TIP 2: you can get off all lists at once with the unregister command (send unregister YourEmailAddressHere to [EMAIL PROTECTED])
Re: [PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
Sean Chittenden [EMAIL PROTECTED] writes: Every few months one of the uber core BSD hackers threatens to rewrite that part of PG because high up in the BSD camp, it's common belief that shm* is a source of performance loss for PostgreSQL. They're full of it. RAM is RAM, no? Once you've got the memory mapped into your address space, it's hard to believe that it matters how you got hold of it. In any case, mmap doesn't have the semantics we need. See past discussions. regards, tom lane ---(end of broadcast)--- TIP 8: explain analyze is your friend
Re: [PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
If shmmax and shmmall are too small, then: PostgreSQL requires some more shared memory to cache some tables, x Mb, do you want to increase your OS kernel parameters? Tweak shmmax and shmmall CK Note that this still requires a kernel recompile on FreeBSD :( According to whom? sysctl is your friend. Some sysctl settings may require reboot, but I don't think the SHM ones do. Hmmm...you may be right - I can't prove it now... houston# sysctl -w kern.ipc.shmmax=999 kern.ipc.shmmax: 33554432 - 2147483647 Hrm. Ok. Maybe they've changed that in some recent version :) Chris ---(end of broadcast)--- TIP 4: Don't 'kill -9' the postmaster
Re: [PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
Yes, indeed, sysctl can tweak these values fairly adequately. Now, numbers of semaphors are not as readily tweaked; I wound up limited, the other day, when I tried setting values for... kern.ipc.semmns kern.ipc.semmni Same. Maybe that was the option I was thinking was read-only: houston# sysctl kern.ipc.semmns kern.ipc.semmns: 60 houston# sysctl -w kern.ipc.semmns=70 sysctl: oid 'kern.ipc.semmns' is read only houston# sysctl kern.ipc.semmni kern.ipc.semmni: 10 houston# sysctl -w kern.ipc.semmni=30 sysctl: oid 'kern.ipc.semmni' is read only I like how they use oids :P Chris ---(end of broadcast)--- TIP 3: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
Re: [PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
Nick, I reckon do a system scan first, and parse the current PostgreSQL conf file to figure out what the settings are. Also back it up with a date and time appended to the end to make sure there is a backup before overwriting the real conf file. Then a bunch of questions. What sort of questions would need to be asked and which parameters would these questions affect? So far, and from my limited understanding of the .conf file, I reckon there should be the following Hmmm ... but I do think that there should be a file to store the user's previous answers. That way, the script can easily be re-run to fix config issues. Here is your config of your hardware as detected. Is this correct ? This could potentially be several questions, i.e. one for proc, mem, os, hdd etc Would affect shared_buffers, sort_mem, effective_cache_size, random_page_cost Actually, I think this would break down into: -- Are Proc Mem correct? If not, type in correct values -- Is OS correct? If not, select from list -- Your HDD: is it: 1) IDE 2) Fast multi-disk SCSI or low-end RAID 3) Medium-to-high-end RAID Other things, we don't care about. How was PostgreSQL compiled? This would be parameters such as the block size and a few other compile time parameters. If we can get to some of these read-only parameters than that would make this step easier, certainly for the new recruits amongst us. Actually, from my perspective, we shouldn't bother with this; if an admin knows enough to set an alternate blaock size for PG, then they know enough to tweak the Conf file by hand. I think we should just issue a warning that this script: 1) does not work for anyone who is using non-default block sizes, 2) may not work well for anyone using unusual locales, optimization flags, or other non-default compile options except for language interfaces. 3) cannot produce good settings for embedded systems; 4) will not work well for systems which are extremely low on disk space, memory, or other resouces. Basically, the script only really needs to work for the people who are installing PostgreSQL with the default options or from RPM on regular server or workstation machines with plenty of disk space for normal database purposes. People who have more complicated setups can read the darned documentation and tune the conf file by hand. Is PostgreSQL the only thing being run on this computer? First, becuase it affects a couple of other variables: What kind of database server are you expecting to run? A) Web Server (many small fast queries from many users, and not much update activity) B) Online Transaction Processing (OLTP) database (many small updates constantly from many users; think accounting application). C) Online Analytical Reporting (OLAP) database (a few large and complicated read-only queries aggregating large quantites of data for display) D) Data Transformation tool (loading large amounts of data to process, transform, and output to other software) E) Mixed-Use Database Server (a little of all of the above) F) Workstation (installing this database on a user machine which also has a desktop, does word processing, etc.) If the user answers anything but (F), then we ask: Will you be running any other signficant software on this server, such as a web server, a Java runtime engine, or a reporting application? (yes|no) If yes, then: How much memory do you expect this other software, in total, to regularly use while PostgreSQL is in use? (# in MB; should offer default of 50% of the RAM scanned). How are the clients going to connect? i.e. TCP or Unix sockets We should warn them that they will still need to configure pg_hba.conf. How many clients can connect to this database at once? Affects max_connections Should add a parenthetical comment that for applications which use pooled connections, or intermittent connection, such as Web applications, the number of concurrent connections is often much lower than the number of concurrent users. How many databases and how many tables in each database are going to be present? Affects max_fsm_pages, checkpoint_segments, checkpoint_timeout Also need to ask if they have an idea of the total size of all databases, in MB or GB, which has a stronger relationship to those variables. Also, this will give us a chance to check the free space on the PGDATA partition, and kick the user out with a warning if there is not at least 2xExpected Size available. Do you want to vacuum you database regularly? Initial question for cron job It is recomended that you vacuum analyze every night, do you want to do this? It is also recomended that you vacuum full every month, do you want to do this? Depends on size/type of database. For large OLTP databases, I recommend vacuum as often as every 5 mintues, analyze every hour, and Vacuum Full + Reindex once a week. For a workstation database, your
Re: [PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
Chris, PostgreSQL requires some more shared memory to cache some tables, x Mb, do you want to increase your OS kernel parameters? Tweak shmmax and shmmall Note that this still requires a kernel recompile on FreeBSD :( Not our fault, now is it? This would mean that we wouldn't be able to script for FreeBSD. Bug the FreeBSD developers. -- Josh Berkus Aglio Database Solutions San Francisco ---(end of broadcast)--- TIP 6: Have you searched our list archives? http://archives.postgresql.org
Re: [PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
NB shared_buffers = 1/16th of total memory NB effective_cache_size = 80% of the supposed kernel cache. I think Sean(?) mentioned this one for FreeBSD (Bash code): sh, not bash. :) echo effective_cache_size = $((`sysctl -n vfs.hibufspace` / 8192)) I've used it for my dedicated servers. Is this calculation correct? Yes, or it's real close at least. vfs.hibufspace is the amount of kernel space that's used for caching IO operations (minus the necessary space taken for the kernel). If you're real paranoid, you could do some kernel profiling and figure out how much of the cache is actually disk IO and multiply the above by some percentage, say 80%? I haven't found it necessary to do so yet. Since hibufspace is all IO and caching any net activity is kinda pointless and I assume that 100% of it is used for a disk cache and don't use a multiplier. The 8192, however, is the size of a PG page, so, if you tweak PG's page size, you have to change this constant (*grumbles*). -sc -- Sean Chittenden ---(end of broadcast)--- TIP 2: you can get off all lists at once with the unregister command (send unregister YourEmailAddressHere to [EMAIL PROTECTED])
Re: [PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
On Sat, 2003-10-11 at 05:22, Harald Fuchs wrote: In article [EMAIL PROTECTED], Rod Taylor [EMAIL PROTECTED] writes: Would anyone object to a patch that exports the blocksize via a readonly GUC? Too many tunables are page dependant, which is infuriating when copying configs from DB to DB. I wish pgsql had some notion of percentages for values that end with a '%'. Rather than showing the block size, how about we change the tunables to be physical sizes rather than block based? effective_cache_size = 1.5GB shared_buffers = 25MB Amen! Being forced to set config values in some obscure units rather than bytes is an ugly braindamage which should be easy to fix. But it's too user-friendly to do it this way! -- - Ron Johnson, Jr. [EMAIL PROTECTED] Jefferson, LA USA When Swedes start committing terrorism, I'll become suspicious of Scandanavians. ---(end of broadcast)--- TIP 2: you can get off all lists at once with the unregister command (send unregister YourEmailAddressHere to [EMAIL PROTECTED])
Re: [PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
If shmmax and shmmall are too small, then: PostgreSQL requires some more shared memory to cache some tables, x Mb, do you want to increase your OS kernel parameters? Tweak shmmax and shmmall Note that this still requires a kernel recompile on FreeBSD :( Chris ---(end of broadcast)--- TIP 4: Don't 'kill -9' the postmaster
[PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
Heya Guys n Gals, Having been following the thread on go for a script! / ex: PostgreSQL vs. MySQL. I thought I would throw something together in Perl. My current issue is that I only have access to a RH Linux box and so cannot make it cross-platform on my own :-(. Anyhow please find it attached. It runs fine on my box, it doesnt actually write to postgresql.conf because I didnt want to mess it up, it does however write to postgresql.conf.new for the moment. The diffs seem to be writing correctly. There are a set of parameters at the top which may need to get tweaked for your platform. I can also carry on posting to this list new versions if people want. Clearly this lot is open source, so please feel free to play with it and post patches/new features back either to the list or my email directly. In case you cant see my email address, it is nicky at the domain below. I will also post it on me website and as I develop it further new versions will appear there http://www.chuckie.co.uk/postgresql/pg_autoconfig.pl Is this a useful start? Nick pg_autoconfig.pl Description: Binary data ---(end of broadcast)--- TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]
Re: [PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
- Original Message - From: Nick Barr [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Friday, October 10, 2003 1:35 PM Subject: go for a script! / ex: PostgreSQL vs. MySQL I will also post it on me website and as I develop it further new versions will appear there http://www.chuckie.co.uk/postgresql/pg_autoconfig.pl Make that http://www.chuckie.co.uk/postgresql/pg_autoconfig.txt Nick ---(end of broadcast)--- TIP 4: Don't 'kill -9' the postmaster
Re: [PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
Nick, Having been following the thread on go for a script! / ex: PostgreSQL vs. MySQL. I thought I would throw something together in Perl. Cool! Would you be willing to work with me so that I can inject some of my knowledge of .conf tuning? -- Josh Berkus Aglio Database Solutions San Francisco ---(end of broadcast)--- TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]
Re: [PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
SC == Sean Chittenden [EMAIL PROTECTED] writes: SC patches to extract info from their OS so that initdb can make useful SC decisions. Or, lastly, does anyone think that this should be in a SC different, external program? -sc Well, there should definitely be a way to run a get current best tuning advice for those times when I go and do something like add a Gig of RAM. ;-) Also, I'm sure the tuning advice will change over time, so having to do initdb to get that advice would be a bit onerous. As long as initdb has an option for just getting the tuning info, I see no reason to make it separate. -- =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Vivek Khera, Ph.D.Khera Communications, Inc. Internet: [EMAIL PROTECTED] Rockville, MD +1-240-453-8497 AIM: vivekkhera Y!: vivek_khera http://www.khera.org/~vivek/ ---(end of broadcast)--- TIP 8: explain analyze is your friend
Re: [PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
NB == Nick Barr [EMAIL PROTECTED] writes: NB So far: NB shared_buffers = 1/16th of total memory NB effective_cache_size = 80% of the supposed kernel cache. Please take into account the blocksize compiled into PG, too... -- =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Vivek Khera, Ph.D.Khera Communications, Inc. Internet: [EMAIL PROTECTED] Rockville, MD +1-240-453-8497 AIM: vivekkhera Y!: vivek_khera http://www.khera.org/~vivek/ ---(end of broadcast)--- TIP 6: Have you searched our list archives? http://archives.postgresql.org
Re: [PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
Vivek, NB shared_buffers = 1/16th of total memory NB effective_cache_size = 80% of the supposed kernel cache. Please take into account the blocksize compiled into PG, too... We can;t change the blocksize in a script that only does the .conf file. Or are you suggesting something else? -- Josh Berkus Aglio Database Solutions San Francisco ---(end of broadcast)--- TIP 1: subscribe and unsubscribe commands go to [EMAIL PROTECTED]
Re: [PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
JB == Josh Berkus [EMAIL PROTECTED] writes: JB Vivek, NB shared_buffers = 1/16th of total memory NB effective_cache_size = 80% of the supposed kernel cache. Please take into account the blocksize compiled into PG, too... JB We can;t change the blocksize in a script that only does the .conf JB file. Or are you suggesting something else? when you compute optimal shared buffers and effective cache size, these are in terms of blocksize. so if I have 16k block size, you can't compute based on default 8k blocksize. at worst, it would have to be a parameter you pass to the tuning script. ---(end of broadcast)--- TIP 7: don't forget to increase your free space map settings
Re: [PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
NB So far: NB shared_buffers = 1/16th of total memory NB effective_cache_size = 80% of the supposed kernel cache. Please take into account the blocksize compiled into PG, too... Would anyone object to a patch that exports the blocksize via a readonly GUC? Too many tunables are page dependant, which is infuriating when copying configs from DB to DB. I wish pgsql had some notion of percentages for values that end with a '%'. -sc -- Sean Chittenden ---(end of broadcast)--- TIP 8: explain analyze is your friend
Re: [PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
Sean Chittenden wrote: NB So far: NB shared_buffers = 1/16th of total memory NB effective_cache_size = 80% of the supposed kernel cache. Please take into account the blocksize compiled into PG, too... Would anyone object to a patch that exports the blocksize via a readonly GUC? Too many tunables are page dependant, which is infuriating when copying configs from DB to DB. I wish pgsql had some notion of percentages for values that end with a '%'. -sc Makes sense to me --- we already have some read-only GUC variables. -- Bruce Momjian| http://candle.pha.pa.us [EMAIL PROTECTED] | (610) 359-1001 + If your life is a hard drive, | 13 Roberts Road + Christ can be your backup.| Newtown Square, Pennsylvania 19073 ---(end of broadcast)--- TIP 6: Have you searched our list archives? http://archives.postgresql.org
Re: [PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
On Fri, 2003-10-10 at 18:59, Sean Chittenden wrote: NB So far: NB shared_buffers = 1/16th of total memory NB effective_cache_size = 80% of the supposed kernel cache. Please take into account the blocksize compiled into PG, too... Would anyone object to a patch that exports the blocksize via a readonly GUC? Too many tunables are page dependant, which is infuriating when copying configs from DB to DB. I wish pgsql had some notion of percentages for values that end with a '%'. Rather than showing the block size, how about we change the tunables to be physical sizes rather than block based? effective_cache_size = 1.5GB shared_buffers = 25MB Percentages would be slick as well, but doing the above should fix most of the issue -- and be friendlier to read. signature.asc Description: This is a digitally signed message part
[PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
Hi guys, I followed the discussion and here are my 0.2$: I think instead of thinking about where to put the information about tuning, someone should provide a pgsql-autotune. Maybe even a shell script would do the trick. It's not so hard to find out, how much memory is installed, and IMHO SHARED_BUFFERS, SORT_MEM and EFFECTIVE_CACHE_SIZE depend heavily on this. a cat /proc/sys/kernel/shmmax would give some valuable information on linux boxes, there is probably other stuff for different OSes. random_page_cost could be set after probing the harddisks, maybe even do a hdparm -tT if they seem to be ATA, not SCSI. Now, let's pretend the script finds out there is 1 GB RAM, it could ask something like Do you want to optimize the settings for postgres (other applications may suffer from having not enough RAM) or do you want to use moderate settings? Something like this, you get the idea. This would give new users a much more usable start than the current default settings and would still leave all the options to do fine-tuning later. I guess my point is simply this: instead of saying: okay we use default settings that will run on _old_ hardware too we should go for a little script that creates a still save but much better config file. There's just no point in setting SHARED_BUFFERS to something like 16 (what's the current default?) if the PC has = 1 GB of RAM. Setting it to 8192 would still be save, but 512 times better... ;-) (IIRC 8192 would take 64 MB of RAM, which should be save if you leave the default MAX_CONNECTIONS.) As said before: just my $0.2 My opinion on this case is Open Source. Feel free to modify and add. :-) regards, Oli ---(end of broadcast)--- TIP 3: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
Re: [PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
On 09/10/2003 09:29 Oliver Scheit wrote: Hi guys, I followed the discussion and here are my 0.2$: I think instead of thinking about where to put the information about tuning, someone should provide a pgsql-autotune. Maybe even a shell script would do the trick. It's not so hard to find out, how much memory is installed, and IMHO SHARED_BUFFERS, SORT_MEM and EFFECTIVE_CACHE_SIZE depend heavily on this. a cat /proc/sys/kernel/shmmax would give some valuable information on linux boxes, there is probably other stuff for different OSes. random_page_cost could be set after probing the harddisks, maybe even do a hdparm -tT if they seem to be ATA, not SCSI. Now, let's pretend the script finds out there is 1 GB RAM, it could ask something like Do you want to optimize the settings for postgres (other applications may suffer from having not enough RAM) or do you want to use moderate settings? Something like this, you get the idea. ISR reading that 7.4 will use a default of shared_beffers = 1000 if the machine can support it (most can). This alone should make a big difference in out-of-the-box performance. -- Paul Thomas +--+-+ | Thomas Micro Systems Limited | Software Solutions for the Smaller Business | | Computer Consultants | http://www.thomas-micro-systems-ltd.co.uk | +--+-+ ---(end of broadcast)--- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faqs/FAQ.html
Re: [PERFORM] go for a script! / ex: PostgreSQL vs. MySQL
Yeah, I had similar thought to Oliver's and suspected that this would be the answer. Also, while it's not too hard to do this for a single platform, it gets complecated once you start looking at different ones. Josh, let me know when you're ready to do this. I'll try to help, although my perl's kind of rusty. Also, can you even assume perl for a postgres install? Does Solaris, for instance come with perl? Dror On Thu, Oct 09, 2003 at 09:56:11AM -0700, Josh Berkus wrote: Oliver, I think instead of thinking about where to put the information about tuning, someone should provide a pgsql-autotune. Maybe even a shell script would do the trick. Well, you see, there's the issue. I think someone. Lots of people have spoken in favor of an auto-conf script; nobody so far has stepped forward to get it done for 7.4, and I doubt we have time now. I'll probably create a Perl script in a month or so, but not before that -- Josh Berkus Aglio Database Solutions San Francisco ---(end of broadcast)--- TIP 4: Don't 'kill -9' the postmaster -- Dror Matalon Zapatec Inc 1700 MLK Way Berkeley, CA 94709 http://www.zapatec.com ---(end of broadcast)--- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faqs/FAQ.html
