Re: SQL Cursor Questions

[pytel@xxxxxxxxxx]

> However, even though
> I'm selecting records from a keyed logical file, the records are ordered
by
> the physical file's RRN order.  In other words, the access path
associated
> with the logical file is not used.  When I execute the very same
statement
> interactively, it uses the access path of the logical.  The only
difference
> is the cursor is not used in the interactive version.  Is this normal
> operation for cursors or am I doing something wrong? I know I can use an
> Order by clause to put the records in the same order as the logical is
> keyed, but why doesn't it use the logical's access path in the first
place?


SQL does not care, whether you address PF or LF - it will always use
underlying data in the way it considers is most optimal.
The difference between SQL in interactive session and SQL imbedded in a
program is that optimization goals are slightly different.
By defaut, interactive SQL is biased to returning first screenful of data
as fast as possible, and imbedded SQL is geared to reduce entire processing
time. This will explain why access path was used for interactive and not
for batch - arrival access path may be more efficient if large subset of
file records is selected.


Best regards
    Alexei Pytel



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