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Re^3: Testing if an array contains a value and then deleting it in most efficient way

by parv (Vicar)
on Feb 18, 2008 at 16:43 UTC ( #668601=note: print w/replies, xml ) Need Help??


in reply to Re^2: Testing if an array contains a value and then deleting it in most efficient way
in thread Testing if an array contains a value and then deleting it in most efficient way

A side note ... The records may be sorted but will not be returned as such when not asked, if database server is Sybase 15.0.x.

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Re^4: Testing if an array contains a value and then deleting it in most efficient way
by mpeppler (Vicar) on Feb 19, 2008 at 11:03 UTC
    Even more of a side note - one should never rely on the inherent ordering of data in a SQL database. Any ordering is a side effect of the storage mechanism, and can change (for example due to parallel query engines).

    Always use an ORDER BY clause if the order of the returned data is significant in any way!

    Michael

    PS - for Sybase it's not only ASE 15.0.x that has this behavior - it's any table that has row-level locking (DOL), or if you have partitioned tables, or if you use parallel queries.

      Currently being trained on the job as a DBA (to a level enough to keep servers working), I appreciate your post script much. In any case, change from all-page lock to any other locking scheme won't come as shocking surprise now (w.r.t. output ordering) after switching from 12.0 to 15.0.x.

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