Hi



We currently have some databases running under 8.0 and 8.1. I have noticed
a significant difference in the time taken to restore dumps between the two
versions, with 8.0 being much faster. For example a dump of a few MB will
take just seconds to load under 8.0 but the same dump will take several
minutes to load under 8.1. Currently we're just using the default parameter
settings when installed via apt on Ubuntu Linux.



I would just like to know if this is a well known issue and if there is a
quick fix, or should I be digging deeper and seeing if the default settings
are mismatched to certain linux kernel settings etc.



Any help would be most appreciated.



Thanks,

Ted

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  • Merlin Moncure at Aug 6, 2007 at 1:56 am

    On 8/5/07, Ted Jordan wrote:
    We currently have some databases running under 8.0 and 8.1. I have noticed
    a significant difference in the time taken to restore dumps between the two
    versions, with 8.0 being much faster. For example a dump of a few MB will
    take just seconds to load under 8.0 but the same dump will take several
    minutes to load under 8.1. Currently we're just using the default parameter
    settings when installed via apt on Ubuntu Linux.
    a few seconds to several minutes is not the kind of variance that is
    explainable by architecture changes between the versions. something
    is amiss. 'maintenance_work_mem' can make a big difference with data
    loads due to faster index builds but even that would not account for
    the difference.

    are you running locally or remotely? if running remotely, you might
    be seeing some networking/tcp problems.

    can you reduce your problem down to a single copy statement for analysis?

    merlin
  • Ted Jordan at Aug 6, 2007 at 5:59 pm
    Thanks Merlin. I was running both via ssh so it effectively these were
    local results. I will try to isolate the issue to a single statement. But
    I think you have answered the larger question i.e. there is no well known
    situation where this happens so I should expect to see roughly the same
    performance between 8.0 and 8.1 for data loads and will therefore focus on
    the specifics of our environment.

    Regards,
    -Ted.

    -----Original Message-----
    From: pgsql-performance-owner@postgresql.org
    On Behalf Of Merlin Moncure
    Sent: 6 August 2007 1:57 p.m.
    To: Ted Jordan
    Cc: pgsql-performance@postgresql.org
    Subject: Re: [PERFORM] Default Performance between 8.0 and 8.1
    On 8/5/07, Ted Jordan wrote:
    We currently have some databases running under 8.0 and 8.1. I have noticed
    a significant difference in the time taken to restore dumps between the two
    versions, with 8.0 being much faster. For example a dump of a few MB will
    take just seconds to load under 8.0 but the same dump will take several
    minutes to load under 8.1. Currently we're just using the default parameter
    settings when installed via apt on Ubuntu Linux.
    a few seconds to several minutes is not the kind of variance that is
    explainable by architecture changes between the versions. something
    is amiss. 'maintenance_work_mem' can make a big difference with data
    loads due to faster index builds but even that would not account for
    the difference.

    are you running locally or remotely? if running remotely, you might
    be seeing some networking/tcp problems.

    can you reduce your problem down to a single copy statement for analysis?

    merlin

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