Thursday, March 14, 2013

Informatica Realtime Interview Questions on Rank Transformation

1. What is rank transformation?

A rank transformation is used to select top or bottom rank of data. This means, it selects the largest or smallest numeric value in a port or group. Rank transformation also selects the strings at the top or bottom of a session sort order. Rank transformation is an active transformation.

2. What is rank cache?

The integration service compares input rows in the data cache, if the input row out-ranks a cached row, the integration service replaces the cached row with the input row. If you configure the rank transformation to rank across multiple groups, the integration service ranks incrementally for each group it finds. The integration service stores group information in index cache and row data in data cache.

3. What is RANKINDEX port?

The designer creates RANKINDEX port for each rank transformation. The integration service uses the rank index port to store the ranking position for each row in a group.

4. How do you specify the number of rows you want to rank in a rank transformation?

In the rank transformation properties, there is an option 'Number of Ranks' for specifying the number of rows you wants to rank.

5. How to select either top or bottom ranking for a column?

In the rank transformation properties, there is an option 'Top/Bottom' for selecting the top or bottom ranking for a column.

6. Can we specify ranking on more than one port?

No. We can specify to rank the data based on only one port. In the ports tab, you have to check the R option for designating the port as a rank port and this option can be checked only on one port.

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