| From: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Bruce Momjian <bruce(at)momjian(dot)us>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Magnus Hagander <magnus(at)hagander(dot)net> |
| Subject: | Re: Further pg_upgrade analysis for many tables |
| Date: | 2012-11-14 20:01:09 |
| Message-ID: | 20121114200109.GA12213@alvh.no-ip.org |
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| Lists: | pgsql-hackers |
Tom Lane escribió:
> Jeff Janes <jeff(dot)janes(at)gmail(dot)com> writes:
> > The next quadratic behavior is in init_sequence.
>
> Yeah, that's another place that is using a linear list that perhaps
> should be a hashtable. OTOH, probably most sessions don't touch enough
> different sequences for that to be a win.
Could we use some adaptive mechanism here? Say we use a list for the
first ten entries, and if an eleventh one comes in, we create a hash
table for that one and all subsequent ones. All future calls would
have to examine both the list for the first few and then the hash table.
--
Álvaro Herrera http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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