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Re: [HACKERS] TransactionStateData and AbsoluteTime

From: Thomas Lockhart <lockhart(at)alumni(dot)caltech(dot)edu>
To: Peter Eisentraut <peter_e(at)gmx(dot)net>
Cc: Tatsuo Ishii <t-ishii(at)sra(dot)co(dot)jp>, pgsql-hackers(at)postgreSQL(dot)org
Subject: Re: [HACKERS] TransactionStateData and AbsoluteTime
Date: 2000-03-06 23:12:39
Message-ID: 38C43B67.EEBF3964@alumni.caltech.edu (view raw or flat)
Thread:
Lists: pgsql-hackers
> > Shouldn't we use timestamp instead of AbsoluteTime in
> > TransactionStateData?  It also gives more precision.
> Thomas was hesitant to using 8 byte types internally across the board. He
> must have his reasons.

Yes, I believe that I discussed it at that time, though not perhaps
all of these points:

I was hesitant to suggest a change which would increase the minimum
size of a tuple.

I was hesitant to tie the fundamental internal operation to modern
floating point performance on machines (it is only recently that float
calculations are comparable to ints).

On 64 bit machines especially, it may be interesting to do a 64 bit
int for the date/time types, which would give greater precision away
from Y2K, but a more limited total range.

To get a precision greater than 1 second, we would have to use a
different time call from the OS. I assume that one would be fairly
portable, but would then require a conversion of int8 to float, with
some runtime expense.

And I haven't seen a great demand for greater precision in the table
structures, though istm that it might be of interest.

                      - Thomas

-- 
Thomas Lockhart				lockhart(at)alumni(dot)caltech(dot)edu
South Pasadena, California

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