Re: BUG #14530: Logical Decoding Slowness

On 2017-02-10 06:33:30 +0000, Huan Ruan wrote:
> >
> >
> > Could you give a bit more detail abou thtis one - it indeed looks like
> > different profile, but it's hard to nail down without more lines...
> >
> >
> First screen of unexpanded output:
>
> …
>
> + 94.84% 0.00% postgres postgres
> [.] ExecMakeTableFunctionResult
> + 94.84% 0.00% postgres postgres
> [.] pg_logical_slot_get_changes_guts
> + 94.80% 0.00% postgres postgres
> [.] LogicalDecodingProcessRecord
> + 94.45% 0.03% postgres postgres
> [.] ReorderBufferCommit
> + 94.19% 0.01% postgres postgres
> [.] ReorderBufferCleanupTXN
> + 94.11% 0.01% postgres postgres
> [.] ReorderBufferReturnChange
> + 94.08% 93.40% postgres postgres
> [.] AllocSetFree
>
> + 2.33% 0.00% perf [kernel.kallsyms]
> [k] system_call_fastpath

Ok, so this is likely a known issue. If you're in the position to try,
there's a set of patches to address this:
http://archives.postgresql.org/message-id/20ca0c69-e8c3-cb50-4456-f03908c672ec%402ndquadrant.com

Andres