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Message Posted: Sat, 01 Nov 2003 @ 15:29:52 GMT

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Subj:   Re: Number of sessions for mload / fastload
From:   Muhammad Altaf

MultiLoad Performance Tips

To improve MultiLoad performance, the following tips may be useful:

Minimize concatenation and redefinition of input data.

Restrict the number of non-unique secondary indexes.

Make the primary index of the table unique or nearly unique.

Minimize the use of error tables.

Do not checkpoint too often.

Avoid using too many sessions.

BTEQ Performance Tips

To improve performance of BTEQ, the following tips may be useful.

If you are performing full table scans (all-AMP operation) then do not use multiple sessions. Use a single session.

If operations that require less than all-AMPs then use multiple sessions.

If primary index operation then determine empirically the optimum number of sessions. More sessions do not necessarily improve performance.

If operations that do not require statement accounting to be returned to your output file then SET QUIET ON.

FastExport Performance Tips

To improve performance, the following tips may be useful.

Do not use too many sessions.

Avoid NULLIF clauses, concatenated fields, APPLY WHERE conditions, or any other option that causes the evaluation of individual fields within a layout.

FASTLOAD Performance Tips

FastLoad performance is affected by the row size and the number of columns more than any other factors. Because it is not usually an option to reduce the rows and columns, the following tips may be useful in improving performance when you load large tables:

If you are loading a large table without fallback then

set session to the number of AMPs in your system.

avoid checkpointing too frequently.

avoid NULLIF clauses, VAR fields, and/or indicator bits whenever possible.

run concurrent FastLoad jobs instead of just one (maximum number is 15).

If you are loading a large table with fallback protection

observe the suggestions for loading the large table without fallback.

create the table without fallback protection.

load the table.

use BTEQ to alter the table to have fallback protection.

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