Re: More time zones - Mailing list pgsql-hackers

From Tom Lane
Subject Re: More time zones
Date
Msg-id 26943.1014695370@sss.pgh.pa.us
Whole thread Raw
In response to Re: More time zones  (Thomas Lockhart <lockhart@fourpalms.org>)
List pgsql-hackers
Thomas Lockhart <lockhart@fourpalms.org> writes:
> Certainly possible. At the moment the algorithm uses a binary search
> through a fixed size array of choices; reading from a table would
> require changes to a linked list or something else which is not quite as
> fast.

Binary search doesn't depend on a fixed size table.  How about:

1. At startup, read & parse TZ config file; build array and sort it.

2. During keyword lookup, first binary-search the array of fixed
keywords.  If no match, binary-search the TZ array.

(This assumes that TZ names are not allowed to pre-empt other names,
such as month names.  In some situations the parser might know that
a TZ name is expected, in which case it could go to the TZ array only,
thus allowing conflicting names to be resolved.)

> istm that a database table lookup is the way to internationalize and
> extend this area,

Um ... in the previous paragraph you were complaining about the
performance hit of doing a linear search.  Which are you more concerned
about, speed or instant configurability?

This is by no means meant as an attack on the current implementation,
just a thought that we might be reaching its limits.  If the Australians
want a configurable set of timezone names, why won't other areas?
        regards, tom lane


pgsql-hackers by date:

Previous
From: Thomas Lockhart
Date:
Subject: Re: More time zones
Next
From: Thomas Lockhart
Date:
Subject: Re: Timezone Inconsistancies