Jeff:

Thanks for responding! I have edited out some bits to keep this as
brief as possible.

> Shared buffers on the origin or the subscriber? Shared buffers might not
> matter in this case anyway.

I upped the shared_buffers on both the origin and subscriber from
20,000 to 40,000 then did a reload (not a restart) in Postgres on both
the origin and the subscriber.

> A Slony subscriber reads from the log on the origin and then writes the
> records on the subscriber in separate statements. For any bulk operation
> on the origin (like a big UPDATE statement) that translates into a lot
> of little statements on the subscriber. Usually, each of those little
> statements uses an index, because that's fastest for an action on a
> single tuple.

My mass update was comprised of all individual, one record, updates
per transaction.

> If you don't have enough memory to hold the index, that translates into
> bad performance.
>
> Tell us more about the situation. Is the index fitting in shared memory?
> How big is the table? How much physical memory?

Thanks for the pointed questions. I didn't think any of this was
relevant until I checked. Two of my 12 indexes are bigger (as measured
by 'relpages') than the table itself. These are 8k pages right?

SELECT relname, reltuples, relpages FROM pg_class ORDER BY relpages DESC ;
             relname             |  reltuples  | relpages
---------------------------------+-------------+----------
 indx_tsearch2a                  |       72559 |    66324
 indx_tsearch2c                  |       40761 |    44640
 used_ad                         |      335542 |    38646

(used_ad is the table, the other two are partial indexes.)

So, my shared_buffers is 40,000 and two of my indexes are bigger than
that. The total size of all 12 indexes is some 324,000 'relpages'.

*** Is shared_buffers comparable to 'relpages'? If so, is it practical
to bump shared_buffers to 325,000? That's just over 2.5GB by my
calculation - I have 3GB on the machine.

> Try to hunt down which events are taking a long time to SYNC.

Please, what would allow me to measure that?

> What other types of bulk operations are you doing? Any big UPDATEs or DELETEs?

Nothing else big during the day, just a steady constant stream.

Thanks again, and in advance, for your sage advice.

- Don Barthel