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Re: pg_dump slower than pg_restore

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On 7/4/2014 9:18 PM, Tom Lane wrote:
There are only 32 table, no functions, but mostly large objects. Not
sure how to know about the LOs, but a quick check from the table sizes I
estimate at only 2GB, so 16GB could be LOs.  There are 7,528,803 entries
in pg_catalog.pg_largeobject.
Hmm ... how many rows in pg_largeobject_metadata?

pg_largeobject_metadata reports 1,656,417 rows.

By the way, what is pg_largeobject_metadata vs. pg_largeobject since the counts are so different?


   7547 esignfor  30  10 1148m 1.0g  852 S  2.3 26.9 14:10.27 pg_dump
--format=c --oids ibc01

I haven't tested it for any side issues, but the --oids can probably be removed as we don't cross reference against OID columns anymore (all OIDs are just a field in a table that uses a UUID now for cross-referencing). But removing it seemed to make no difference if overall time for the pg_dump to complete.

That's a pretty large resident size for pg_dump :-( ... you evidently
have a lot of objects of some sort, and I'm betting it's LOs, but
let's make sure.

Is there postgresql.conf setting that might help? It's a small 1GB RAM Linux VM with Tomcat web server (we give it 500-700MB) with PG DB on it. We don't do much but change max-connections to 70, shared_buffers to 128MB, maintenance_work_mem to 120MB, checkpoint_segments to 6.

But in the end, I guess the main question is why the backup takes longer than the restore, which just seems counter-intuitive to me.

Thanks for all your help and thinking about it!



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