Re: Phantom Inserts

In article <pwongD4C773.F15_at_netcom.com> pwong_at_netcom.com "Philip S. Wong" writes:

>I was wondering how different databases/vendors implement protection
>against phantom inserts. In particular, how can they achieve phantom
>protection while maintaining a good degree of concurrency?
>
>Example:

[snipped]

Funny how both the responses form Oracle personnel mentioned Rdb rather than (original) Oracle. The term "read repeatability" is often used in this situation and is available in Oracle by setting the appropriate isolation level.

Gupta's SQLBase is very similar in this respect.

>
>BTW, how important is the protection against phantom inserts anyway?
>It doesn't seem common in applications that I have seen.

I don't think that I've ever had to worry about it in any application that I've written. Doing the same select twice in a row in the same transaction would be so obviously inefficient that I would try to design around it as a matter of course.

Regards,

-- 
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Bruce Horrocks
Hampshire, England                   Object Oriented programmers only
                                     need two methods - Create and Scoop-Up
bh_at_granby.demon.co.uk
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