On Mon, 29 Aug 2016 13:13:17 -0300 Alvaro Herrera <alvhe...@2ndquadrant.com> wrote:
> Jehan-Guillaume de Rorthais wrote: > > On Mon, 29 Aug 2016 13:38:03 +0200 > > hubert depesz lubaczewski <dep...@depesz.com> wrote: > > > > > Hi, > > > we have rather uncommon case - DB with ~ 50GB of data, but this is > > > spread across ~ 80000 tables. > > > > > > Running pg_dump -Fd -jxx dumps in parallel, but only data, and MOST of > > > the time is spent on queries that run sequentially, and as far as I can > > > tell, get schema of tables, and sequence values. > > > > > > This happens on Pg 9.5. Are there any plans to make getting schema > > > faster for such cases? Either by parallelization, or at least by getting > > > schema for all tables "at once", and having pg_dump "sort it out", > > > instead of getting schema for each table separately? > > Depesz: I suggest you start coding ASAP. > > > Another issue I found in current implementation is how pg_restore deal with > > PK. As it takes an exclusif lock on the table, it is executed alone before > > indexes creation. > > > > Splitting the PK in unique index creation then the constraint creation might > > save a lot of time as other index can be built during the PK creation. > > Yeah. I recall there being some stupid limitation in ALTER TABLE .. ADD > CONSTRAINT USING INDEX to create a primary key from a previously > existing unique index, which would be very good to fix (I don't recall > what it was, but it was something infuriatingly silly). Could you elaborate? I already had to implement some custom scripts to restore some tables using this method. The scripts were using psql and "xargs -P" to restore the indexes and the PK outside of pg_restore. > I suggest you start coding that ASAP. I did start, but with no success so far as the code in pg_dump/pg_restore is quite obscure at a first look. The few attempt I did to catch the PK creation statement and split it in 2 distincts statements failed to be processed in parallel IIRC. I probably dropped the patch in the meantime though. -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
