Re: Query is slower with a large proportion of NULLs in several columns

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 





On Monday, December 20, 2021, Tom Lane <tgl@xxxxxxxxxxxxx> wrote:
Justin Pryzby <pryzby@xxxxxxxxxxxxx> writes:
> On Mon, Dec 20, 2021 at 08:11:42PM -0800, Lars Bergeson wrote:
>> Still taking 10X more I/O to read the smaller table. Very odd.

> If I'm not wrong, it's even worse than that ?
> It takes 20 or 30sec to run the query - but it says the associated I/O times
> are ~500sec or ~6000sec ?

It would help if somebody had labeled the units of I/O Time
... but I'm guessing those are microsec vs. the millisec
of the other times, because otherwise it's completely wrong.


Related to my preceding observation, from the explain (buffers) docs:

“…and the time spent reading and writing data file blocks (in milliseconds) if track_io_timing is enabled.“

David J.


[Postgresql General]     [Postgresql PHP]     [PHP Users]     [PHP Home]     [PHP on Windows]     [Kernel Newbies]     [PHP Classes]     [PHP Books]     [PHP Databases]     [Yosemite]

  Powered by Linux