Thread: Sum of written buffers bigger than allocation?
Hi All! First time I see that the sum of written buffers: 3765929+878326121 = 882092050 = select pg_size_pretty(882092050::numeric*8192) = 6730 GB is bigger than buffers_alloc value in pg_stat_bgwriter view: buffers_alloc | 20426161 = 156 GB buffers_checkpoint | 878599316 buffers_clean | 0 maxwritten_clean | 0 buffers_backend | 3766409 buffers_backend_fsync | 0 buffers_alloc | 20426161 It's kinda mysterious... Any explanations? Does it mean that the same buffers were written over and over again? -- Sent from: http://www.postgresql-archive.org/PostgreSQL-general-f1843780.html
On Sun, Apr 8, 2018 at 11:28 AM, pinker <pinker@onet.eu> wrote:
It's kinda mysterious... Any explanations?
Does it mean that the same buffers were written over and over again?
Yeah, checkpoints will write all dirty buffers, but doesn't evict them. Next time the page is needed, it doesn't need to be re-read as it is still there.
Cheers,
Jeff