Re: Nearest Common Ancestor Report (XDb1's $1000 Challenge)

On Wed, 02 Jun 2004 17:44:18 +1000, thirdrock <iktaccounts at optusnet dot com dot au> wrote:

>On Tue, 01 Jun 2004 23:06:10 +0200, Hugo Kornelis
><hugo_at_pe_NO_rFact.in_SPAM_fo> wrote:
>
>> On Tue, 01 Jun 2004 16:33:34 +1000, thirdrock wrote:
>>
>>> On Sun, 30 May 2004 00:24:48 +0200, Hugo Kornelis
>>> <hugo_at_pe_NO_rFact.in_SPAM_fo> wrote:
>>>
>>>> On 29 May 2004 11:18:22 -0700, Neo wrote:
>>>
>>>> No, they are not. There is no such thing as a "RAM table" in MS SQL
>>>> Server.
>>>
>>> Yes there is. It's called a temporary table. Really fast too, but does
>>> not
>>> get flushed to disk at any point.
>>
>> Hi Ian,
>>
>>
>> If the temp table is small enough to fit in memory and it is dropped soon
>> after being created, then the data may be gone from the cache before
>> being
>> flushed to disk; the log records will still be written to disk (logging
>> for temp tables is reduced, not completely avoided).
>
>This maybe correct, or tempdb may be used as a swap space (like virtual
>memory), so the temp table may not ever go into the cache if it is small
>enough. Without knowing exactly how it is implemented it is hard to say.
>As for logging changes to temp tables, are you sure about that? Not sure
>what the point of that would be ... still I'm not saying it doesn't
>happen, just surprised that it does.

Hi Ian,

I think the tempdb logfile is used to rollback transactions on a temp table. It is not used for recovery after a crash or outage - the tempdb is dropped and recreated every time the SQL Server service is started.

(snip)

Best, Hugo

-- 

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