Not sure why reading from a socket is taking 1ms ? Dave Cramer
da...@postgresintl.com www.postgresintl.com On Mon, 3 Sep 2018 at 09:39, Mate Varga <m...@matevarga.net> wrote: > Hi, > > https://imgur.com/a/ovsJPRv -- I've uploaded the profiling info (as an > image, sorry). It seems this is a JDBC-level problem. I understand that the > absolute timing is not meaningful at all because you don't know how large > the resultset is, but I can tell that this is only a few thousands rows + > few thousand largeobjects, each largeobject is around 1 kByte. (Yes I know > this is not a proper use of LOBs -- it's a legacy db structure that's hard > to change.) > > Thanks. > Mate > > On Mon, Sep 3, 2018 at 11:52 AM Mate Varga <m...@matevarga.net> wrote: > >> Hey, >> >> we'll try to test this with pure JDBC versus hibernate. Thanks! >> >> >> On Mon, Sep 3, 2018 at 11:48 AM Dave Cramer <p...@fastcrypt.com> wrote: >> >>> >>> >>> On Mon, 3 Sep 2018 at 03:55, Mate Varga <m...@matevarga.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.cra...@crunchydata.ca >>> www.crunchydata.ca >>> >>> >>> >>>> Mate >>>> >>>> On Sun, Sep 2, 2018 at 12:55 AM Dave Cramer <p...@fastcrypt.com> wrote: >>>> >>>>> >>>>> >>>>> >>>>> On Fri, 31 Aug 2018 at 10:15, Mate Varga <m...@matevarga.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 <dmit...@gmail.com> >>>>>> wrote: >>>>>> >>>>>>> пт, 31 авг. 2018 г. в 16:35, Mate Varga <m...@matevarga.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 >>>>> >>>>> da...@postgresintl.com >>>>> www.postgresintl.com >>>>> >>>>
