Re: foundations of relational theory? - some references for the truly starving

In article <bn7rd0$tul6k$1_at_ID-152540.news.uni-berlin.de>, Costin Cozianu <c_cozianu_at_hotmail.com> writes
>> This is sometimes true - although not necessarily. The determining
>> factor is whether or not the read or update involves a "frame fault".
>> If no "frame fault" in involved then performance is the same whether
>> the item being accessed is 15 bytes long or 1500. Performance is also
>> equal regardless of the number of items on the file or total file
>> size. It will take no longer to read one 1500 byte item from a 10 gig
>> file containing 30m items than it would to read a 15 byte item from a
>> 10k file containing 100 items.
>>
>
>BS. Or do you mean you don't write to log files ?
Well, that would slow us down slightly, but it would affect both relational and MV
>
>You also have to count that increasing record size decreases the number of rows
>stored in a single page (frame)

SO WHAT! Mike said he was retrieving ONE row, at random, from a file. Who cares how many rows fit in each frame if you're just looking for one.

Oh - and you want the stats? On average, to retrieve any one row, chosen at random, you need to read just *1.05* frames either to retrieve the row from its primary key, or to know that that primary key doesn't exist! The size of the file doesn't enter into the equation.

Cheers,
Wol

-- 
Anthony W. Youngman - wol at thewolery dot demon dot co dot uk
Witches are curious by definition and inquisitive by nature. She moved in. "Let 
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