Comments on ITNirvanas (Datwarehousing/Oracle/Informatica/Unix/D2K Plus interview questions): Best Practices in Informatica (Part1)

Hello, Very nice posts. Really appreciate your ef...

2009-10-13T15:23:01.936-07:00

Hello,
Very nice posts. Really appreciate your efforts.

I have doubt in determining the Look up cache size and index cache size for the lookup transformation. On which terms we will decide the size of those?

For example, if we have a target of size 100GB and we are taking that target as look up table can we go with the default size of look up cache and index cache? If we need to change the cache, on what measure we need to change them?

Thanks in advance.

--
suri

Sorry, I think I forgot to paste the article link....

2009-04-23T01:39:00.000-07:00

Sorry, I think I forgot to paste the article link.

http://radhakrishnasarma.blogspot.com/2008/02/informatica-powercenter-performance.html

Cheers
Sarma.

Hi, I've given this suggestion and few more ...

2009-04-17T02:28:00.000-07:00

Hi,

I've given this suggestion and few more in this article. Please have a look at it.

Cheers
Sarma.

Thanks Sarma for visiting ITNirvanas and giving yo...

2009-04-09T08:22:00.000-07:00

Thanks Sarma for visiting ITNirvanas and giving your valuable comments.

1024 is bytes.I was trying to say if no of rows in lookuptable are more than 500000 with rowsize 1024 Bytes then it is normally recommended to not use cache.

But having said that i should have also mentioned it also depends how many source rows you are reading.

Thanks for pointing out.

Let us say, you have 10 rows in the source and one of the columns has to be checked against a big table (1 million rows). Then PowerCenter builds the cache for the lookup table and then checks the 10 source rows against the cache. It takes more time to build the cache of 1 million rows than going to the database 10 times and lookup against the table directly. Use uncached lookup instead of building the static cache, as the number of source rows is quite less than that of the lookup.

I did small test on this and following are results

Source Lkp W/O-Cache(Secs) Cache(Secs)
10 500000 13 60
1000 500000 12 50
10000 500000 28 50
100000 500000 169 60

Row size was 1024 Bytes.

Please continue to give your valuable inputs.

hi, Can you tell how you came to the conclusion...

2009-04-05T22:49:00.000-07:00

hi,
Can you tell how you came to the conclusion of point 9? What units is 1024 in here? KB? Bytes? I assume it as bytes and your 550000 rows comes in as 500 KB. If I assume it as 1024 KB, then the 550000 rows contribute to 500 MB.

What are trying to infer here?

Cheers
Sarma.