Re: [BUGS] 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