[GENERAL] perc 9 series fastpath feature for database data

Hi, I need advice regarding RAID Controller configuration for PostgreSQL data. Known common best practices: - RAID cache at least 512MB - BBU is must have - cache mode = write back - disk write cache mode = disabled for hdd and low level ssd and disk write cache mode = enabled for ssd enterprise l

[GENERAL] 9.5: pg_stat_statement and pgbench execution time discrepancies

Hi, During performance tests it was mentioned that pgbench common results are being different from what pg_stat_statements provides. PostgreSQL version 9.5.3, centos 7.2. First run after pg_stat_extension created and first pgbench run. *pgbench *-c 30 -T 300 -U postgres -P 10 -r -v > statement

[GENERAL] postgresql timezone and OS localtime correspondence

Hi, My question is related to correspondence of postgresql "timezone" parameter with OS timezone settings in debian and red hat family systems. In debian by default postgresql "timezone" parameter value is "localtime" and it succesfully gets current OS timezone. (most probably it is not dynamical

[GENERAL] Postgresql SSI: read/write dependencies

Hi, I am working on better insight of postgresql serialization mechanism. The main question is - how to determine serialization behaviour at system level and predict exception: > ERROR: could not serialize access due to read/write dependencies among > transactions > DETAIL: Reason code: Cancele

[GENERAL] Locks acquired by "update" statement within serializable transaction.

Hi, I would ask for clarification about logic of locks acquired by update statements within serializable transactions. Tried postgres 9.3.6 and postgres 9.4.4. *Story 1.* testdb=# \dS+ t > Table "public.t" > Column | Type | Modifiers | Storage | Stats target | Descr

Re: [GENERAL] Buffers: shared hit/read to shared_buffers dependence

postgres applies to hard drive or OS cache buffer? 2015-09-09 0:47 GMT+03:00 Merlin Moncure : > On Sat, Sep 5, 2015 at 3:28 PM, Albe Laurenz > wrote: > > Pavel Suderevsky wrote: > >> When I have been passing through "Understanding explain" manual ( > http

[GENERAL] Buffers: shared hit/read to shared_buffers dependence

Hi, When I have been passing through "Understanding explain" manual ( http://www.dalibo.org/_media/understanding_explain.pdf) I've faced some strange situation when table with size of 65MB completely placed in cache with shared_buffers=320MB and it doesn't with shared_buffers <= 256MB. Actually be