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lookup on hash file
Posted: Fri Dec 15, 2006 11:19 am
by dr46014
hi
i have approximately 10000 records in a hash file and i am doing a look up on this hash file for populating the target tables.i am getting update for the hash file every 15days.so how can i refesh my hash file so that look up will be effective.i dont want to use ODBC for look up
Posted: Fri Dec 15, 2006 11:22 am
by DSguru2B
Build the hashed file again. This way it will be refreshed by the most currect records.
Posted: Fri Dec 15, 2006 11:25 am
by dr46014
ok thanks
Posted: Fri Dec 15, 2006 3:23 pm
by ray.wurlod
Enable write cache when (re-)populating your hashed file. It makes a notable difference.
Posted: Fri Dec 15, 2006 3:56 pm
by Dsnew
Ray, When you said "Enable write cache"
Does that mean check the "Allow stage write cache"
Also in a hashed file when do you use - Pre-loadfile to memory?
Posted: Fri Dec 15, 2006 4:00 pm
by I_Server_Whale
Dsnew wrote:Ray, When you said "Enable write cache"
Does that mean check the "Allow stage write cache"
Also in a hashed file when do you use - Pre-loadfile to memory?
1. Yes.
2. You pre-load a hashed file to memory when the size of the hashed file is low and it greatly improves the performance of a lookup since the hashed file will be in memory and disk I/O is avoided.
Whale.
Posted: Fri Dec 15, 2006 4:03 pm
by Dsnew
Thanks for the info, Naveen :D
Posted: Fri Dec 15, 2006 4:17 pm
by ray.wurlod
1. Yes
2. Yes, unless updating the same hashed file in the same job. In which case disable both write and read cache (since they're separate caches). If the hashed file is tiny (say less than 10 groups) I probably wouldn't bother with read cache either, as its pages are likely to be memory resident in any case.