Re: row filtering for logical replication

I found that with the call to ExecInitExtraTupleSlot() in

pgoutput_row_filter(), then the performance of pgoutput_row_filter()

degrades considerably over the 100,000 invocations, and on my system

it took about 43 seconds to filter and send to the subscriber.

However, by caching the tuple table slot in RelationSyncEntry, this

duration can be dramatically reduced by 38+ seconds.

A further improvement can be made using this in combination with

Peter's plan cache (v16-0004).

I've attached a patch for this, which relies on the latest v16-0001

and v16-0004 patches posted by Peter Smith (noting that v16-0001 is

identical to your previously-posted 0001 patch).

Also attached is a graph (created by Peter Smith – thanks!) detailing

the performance improvement.