[Zope] Sybase: How generate id keys? (surrogate keys)

[Hung Jung Lu]

>From: "Ross Lazarus" <rossl@med.usyd.edu.au>
>identity fields are self-incrementing
>check out http://sybooks.sybase.com/onlinebooks/group-as/srg1100e/sqlre
>f/@Generic__BookTextView/64752;hf=0;cs=default;ts=default#X

Unfortunately the IDENTITY column is not a good option.

According to our local Sybase expert, The IDENTITY columns
are just too buggy to use, even after the newer releases of
Sybase. They cause too many troubles, that is why we are
looking at alternatives. In older versions of Sybase, the
problems were so severe that they would cause the database
server to crash. Some drawbacks that were mentioned:
(some are fixed, but these are not the only problems...)

(1) When database server crashes, apparently the IDENTITY
    column jumps to the next block of values, so the table
    index space become sparsely populated, and you may hit
    the roll-over situation earlier than expected.

(2) When using BCP utility to download and upload tables,
    there are some problems with the IDENTITY columns, too.

(3) It is hard to access the values of the IDENTITY column
    when you are in multiple SQL statements.

Anyway, there seem to be too many problems, so the IDENTITY
column approach has been discarded. :(

regards,

Hung Jung

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