Am 28.03.2018 um 23:38 schrieb Alvar Freude: > Hi all, > > Can someone tell me, what the value of buffers_alloc in the pg_stat_bgwriter > view > (https://www.postgresql.org/docs/current/static/monitoring-stats.html#PG-STAT-BGWRITER-VIEW) > is exactly? Is this the amount of shared buffers used by the bgwriter?
As I had to research that anyway, there's no reason not to write this down here as well... (probably simplified, but I'm quite confident the information is correct ;-): Whenever a buffer is allocated, a global counter is incremented (see "StrategyGetBuffer" in storage/buffer/freelist.c. That counter is used by the BGWriter to determine its own wakeup/hibernate strategy, and on-the-fly written to the global stats. Thus, buffer_alloc is the global count of buffers allocated in the cluster. That it appears in the bgwriter statistics is more or less coincidental. Best regards, -- Gunnar "Nick" Bluth RHCE/SCLA Mobil +49 172 8853339 Email: gunnar.bl...@pro-open.de _____________________________________________________________ In 1984 mainstream users were choosing VMS over UNIX. Ten years later they are choosing Windows over UNIX. What part of that message aren't you getting? - Tom Payne
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