Re: [PERFORM] When to vacuum a table?
Hi, From: http://www.postgresql.org/docs/7.4/interactive/sql-vacuum.html VACUUM reclaims storage occupied by deleted tuples. In normal PostgreSQLoperation, tuples that are deleted or obsoleted by an update are not physically removed from their table; they remain present until a VACUUM is done. Therefore it's necessary to do VACUUM periodically, especially on frequently-updated tables. The vacuum analyze form additionally collects statistics on the disbursion of columns in the database, which the optimizer uses when it calculates just how to execute queries. The availability of this data can make a tremendous difference in the execution speed of queries. This command can also be run from cron, but it probably makes more sense to run this command as part of your nightly backup procedure - if vacuum is going to screw up the database, you'd prefer it to happen immediately after (not before!) you've made a backup! The vacuum command is very reliable, but conservatism is the key to good system management. So, if you're using the export procedure described above, you don't need to do this extra step. All its tables constantly manipulated (INSERT, UPDATE, DELETE) they need a VACUUM, therefore the necessity to execute at least one time to the day normally of dawn if its database will be very great . [],s Marcelo Costa Secretaria Executiva de Educação do Pará Amazonia - Pará - Brazil 2006/11/26, Joost Kraaijeveld [EMAIL PROTECTED]: Hi, Are there guidelines (or any empirical data) available how to determine how often a table should be vacuumed for optimum performance or is this an experience / trial-and-error thing? TIA -- Groeten, Joost Kraaijeveld Askesis B.V. Molukkenstraat 14 6524NB Nijmegen tel: 024-3888063 / 06-51855277 fax: 024-3608416 web: www.askesis.nl ---(end of broadcast)--- TIP 1: 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 -- Marcelo Costa
Re: [PERFORM] When to vacuum a table?
Sorry, realy you are correct. [],s Marcelo Costa. 2006/11/26, Steinar H. Gunderson [EMAIL PROTECTED]: On Sun, Nov 26, 2006 at 09:43:11AM -0300, Marcelo Costa wrote: All its tables constantly manipulated (INSERT, UPDATE, DELETE) they need a VACUUM Just a minor clarification here: INSERT does not create dead rows, only UPDATE and DELETE do. Thus, if you only insert rows, you do not need to vacuum (although you probably need to analyze). /* Steinar */ -- Homepage: http://www.sesse.net/ ---(end of broadcast)--- TIP 1: 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 -- Marcelo Costa
[PERFORM] How much memory in 32 bits Architecture to Shared Buffers is Possible
Hi, to all! Recently i try increasing the memory values of shared buffers on one IBM xseries 255 (Quad XEON 2.8, 8 GB RAM, 2 disk SCSI 36 GB(Raid 1), 1 Storage. I try change these shared memory values to use 25% of memory ram (2048 MB) and effective_cache_size to 50% (4096 MB) of memory. All this settings to 220 Max Connections. Where I start up the cluster very messages of configurations errors on shared_memmory and SHMMAX look up. I try change the values of shared_memory, max_connections and effective_cache_size and large the size of SHMALL and SHMMAX to use 4294967296 (4096 MB) but the cluster don't start. Only with 15% of value on shared memory i can start up this cluster. In my tests the maximum value who i can put is 1.9 GB, more of this the cluster don't start. Can anybody help me and explicate if exist one limit to memory on 32 bits Architecture. Anybody was experience with tuning servers with this configurations and increasing ? thanks to all. -- Marcelo Costa ---(end of broadcast)--- TIP 5: don't forget to increase your free space map settings
Re: [PERFORM] How much memory in 32 bits Architecture to Shared Buffers is Possible
Yes, my system is DEBIAN SARGE 3.0thanks,Marcelo2006/10/2, Joshua D. Drake [EMAIL PROTECTED]: Marcelo Costa wrote: Hi, to all! Recently i try increasing the memory values of shared buffers on one IBM xseries 255 (Quad XEON 2.8, 8 GB RAM, 2 disk SCSI 36 GB(Raid 1), 1 Storage. You haven't specified your OS so I am going to assume Linux. Where I start up the cluster very messages of configurations errors on shared_memmory and SHMMAX look up. I try change the values of shared_memory, max_connections and effective_cache_size and large the size of SHMALL and SHMMAX to use 4294967296 (4096 MB)but the cluster don't start.You have to edit your sysctl.conf see: http://www.postgresql.org/docs/8.1/static/runtime.htmlI *think* (I would have to double check) the limit for shared memory onlinux 32bit is 2 gig. Possibly 2 gig per CPU I don't recall. I run all 64bit now.Sincerely,Joshua D. Drake-- === The PostgreSQL Company: Command Prompt, Inc. ===Sales/Support: +1.503.667.4564 || 24x7/Emergency: +1.800.492.2240 Providing the most comprehensivePostgreSQL solutions since 1997 http://www.commandprompt.com/-- Marcelo Costa
