Re: Question about buffers_alloc in pg_stat_bgwriter view for monitoring

Hi,

> Am 29.03.2018 um 10:30 schrieb Gunnar Nick Bluth <gunnar(dot)bluth(at)pro-open(dot)de>:
>
> 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.

But it seems not to be the total shared_buffers used, but the total number of allocated and re-allocated buffers. So it increments every time a buffer is allocated. Maybe I’m the only one who misunderstands it – or someone with better english then me should update the docs. ;-)

postgres=# SELECT buffers_alloc*current_setting('block_size')::numeric/1024/1024/1024, current_setting('shared_buffers') FROM pg_stat_bgwriter;
?column? | current_setting
-----------------------+-----------------
1219.7707748413085938 | 64450MB
(1 row)

Or other machine:

?column? | current_setting
----------------------+-----------------
126.4642944335937500 | 64450MB
(1 row)

Small one:

?column? | current_setting
--------------------+-----------------
3.3014221191406250 | 6GB
(1 Zeile)

Ciao
Alvar

--
Alvar C.H. Freude | http://alvar.a-blast.org
https://blog.alvar-freude.de/
https://www.wen-waehlen.de/