Re: very slow largeobject transfers through JDBC

On Mon, 3 Sep 2018 at 03:55, Mate Varga <m(at)matevarga(dot)net> wrote:

> Basically there's a class with a byte[] field, the class is mapped to
> table T and the byte field is annotated with @Lob so it goes to the
> pg_largeobject table.
>

Ah, so hibernate is in the mix. I wonder if that is causing some challenges
?

> The DB is on separate host but relatively close to the app, and I can
> reproduce the problem locally as well. One interesting bit is that turning
> of SSL between the app and PSQL speeds up things by at least 50%.
>
> Ah, one addition -- the binary objects are encrypted, so their entropy is
> very high.
>
> Any chance you could write a simple non-hibernate test code to time the
code ?

Dave Cramer

dave(dot)cramer(at)crunchydata(dot)ca
www.crunchydata.ca

> Mate
>
> On Sun, Sep 2, 2018 at 12:55 AM Dave Cramer <pg(at)fastcrypt(dot)com> wrote:
>
>>
>>
>>
>> On Fri, 31 Aug 2018 at 10:15, Mate Varga <m(at)matevarga(dot)net> wrote:
>>
>>> I see -- we could try that, though we're mostly using an ORM (Hibernate)
>>> to do this. Thanks!
>>>
>>> On Fri, Aug 31, 2018 at 3:57 PM Dmitry Igrishin <dmitigr(at)gmail(dot)com>
>>> wrote:
>>>
>>>> пт, 31 авг. 2018 г. в 16:35, Mate Varga <m(at)matevarga(dot)net>:
>>>> >
>>>> > Hi,
>>>> >
>>>> > we're fetching binary data from pg_largeobject table. The data is not
>>>> very large, but we ended up storing it there. If I'm copying the data to a
>>>> file from the psql console, then it takes X time (e.g. a second), fetching
>>>> it through the JDBC driver takes at least 10x more. We don't see this
>>>> difference between JDBC and 'native' performance for anything except
>>>> largeobjects (and bytea columns, for the record).
>>>> >
>>>> > Does anyone have any advice about whether this can be tuned or what
>>>> the cause is?
>>>> I don't know what a reason of that, but I think it's reasonable and
>>>> quite simple to call lo_import()/lo_export() via JNI.
>>>>
>>>
>> Can't imagine that's any faster. The driver simply implements the protocol
>>
>> Do you have any code to share ? Any other information ?
>>
>> Is the JDBC connection significantly further away network wise ?
>>
>>
>> Dave Cramer
>>
>> davec(at)postgresintl(dot)com
>> www.postgresintl.com
>>
>