Обсуждение: [GENERAL] Checkpoint write time - anything unusual?

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[GENERAL] Checkpoint write time - anything unusual?

От
pinker
Дата:
I've just run pgBadger on my pg logs and wonder if those checkpoint
statistics is something I should worry about or not?
The highest write time is about 47 minutes but I'm not sure if that's
checkpoint_completion_target*checkpoint_target value or real time between
sending the command to write and getting response?
If that's the first one - then I assume everything is ok because:checkpoint_timeout = 8mincheckpoint_completion_target
=0.9
 

but I'm not sure which value it is...

Hour  Written buffers    Write time    Sync time    Total time
00    104,622    2,510.379s    0.558s    2,511.144s
01    23,549     2,218.747s    0.298s    2,219.199s
02    9,776      919.796s      0.244s    920.281s
03    1,075      107.07s       0.398s    107.667s
04    1,062      105.853s      0.396s    106.384s
05    16,216     1,609.462s    0.576s    1,610.245s
06    38,315     2,137.492s    0.246s    2,137.879s
07    51,504     2,571.057s    0.48s     2,571.7s
08    53,921     2,295.652s    2.071s    2,297.957s
09    18,716     1,116.161s    3.132s    1,119.715s
10    9,000      581.912s      3.866s    586.109s
11    12,795     879.337s      2.427s    882.124s
12    13,872     860.987s      1.127s    862.444s
13    14,883     805.011s      0.866s    806.119s
14    13,172     1,062.677s    1.228s    1,064.188s
15    9,375      620.979s      1.013s    622.632s
16    6,268      626.158s      1.059s    627.721s
17    12,387     613.113s      4.849s    618.534s
18    40,641     1,791.432s    1.571s    1,793.546s
19    38,316     1,946.747s    1.343s    1,948.442s
20    69,564     2,817.917s    1.268s    2,819.678s
21    17,333     1,736.004s    0.812s    1,737.25s
22    9,230      924.742s      0.576s    925.49s
23    118,037    2,150.212s    2.167s    2,152.673s



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Re: [GENERAL] Checkpoint write time - anything unusual?

От
Laurenz Albe
Дата:
pinker wrote:
> I've just run pgBadger on my pg logs and wonder if those checkpoint
> statistics is something I should worry about or not?
> The highest write time is about 47 minutes but I'm not sure if that's
> checkpoint_completion_target*checkpoint_target value or real time between
> sending the command to write and getting response?
> If that's the first one - then I assume everything is ok because:
>  checkpoint_timeout = 8min
>  checkpoint_completion_target = 0.9
> 
> but I'm not sure which value it is...

I think that is fine.

if checkpoint_completion_target is 0.9, spending 0.9 * 3600 = 3240
seconds
per hour doing checkpoints would be normal.

The whole point of this parameter is to spread checkpoints across
a longer time to avoid I/O spikes.

Yours,
Laurenz Albe


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