Re: Providing catalog view to pg_hba.conf file - Patch submission

On Mon, Mar 2, 2015 at 1:42 PM, Greg Stark <stark(at)mit(dot)edu> wrote:

> ​So earlier someone commented that using lists list_nth() seemed odd and a
> tuplestore might be better. In fact using lists this way is O(n^2). I've
> done some quick tests and it doesn't start being a problem until about
> 10,000 lines which obviously isn't a terribly common way to use
> pg_hba_settings. However we have in the past had people doing multi-tenant
> clusters with hundreds or thousands of databases in a cluster complaining
> about scalability of certain operations. It would be a shame to introduce a
> new one.
>
> It does seem annoying to use a tuplestore as IIRC the function scan node
> also materializes the results in recent years. But at least it would scale
> linearly.
>

So I didn't get the memo about SFRM_Materialize. Here's a rewrite of this
using that interface which seems to test ok up to 100k. At that point I
start running into memory errors on reading the HBA file so I guess that's
an indication that's large enough to stop worrying about it.

--
greg