Re: AW: SQL versus READ for sequential processing

Hello Birgitta,

That is not entirely true (anymore). Since V5R4 command CRTLF has an extra parameter PAGESIZE. I just tested:

First I created a logical file without changing the pagesize and then created an index (with the same key field). Access path was not shared.

Next I created a logical file with PAGESIZE(64) and then the corresponding index. Now the access path was shared.

Joep Beckeringh


Birgitta Hauser schreef:

Hi,

I just tried something like this - there is no sharing of access path.

There is, but you have to know an SQL index will never share access path
with a DDS described logical file because of the larger page size of the SQL
index (64K versus 8K).
But a DDS described logical file can share access path with an SQL index
(and even gets inherited the larger page size).
In this way delete the logical file, create the SQL index and recreate the
logical file and voilà only a single access path will be created.

If the ignore derived index option in the QAQQINI-file is set to *YES, the
SQE can use the newly created SQL index while the DDS described logical file
can be used by native I/O and only a single access path must be maintained. Keep in mind each additional access path will decrease performance, because
access paths get actualized as soon as a row gets inserted, updated or
deleted in the base table (or physical file).

Mit freundlichen Grüßen / Best regards

Birgitta Hauser

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