- Rank Transformation
The Rank transformation allows us to select the top or bottom rank of the data.
- When the IS runs in the ASCII data movement mode, it sorts session data using a binary sort order.
- For Unicode data movement mode, it uses the sort order configured for the session.
Rank Caches
The IS stores group information in an index cache and row data in a data cache.
During a workflow, the IS compares an input row with rows in the data cache. If the input row out-ranks a cached row, the IS replaces a cached row with input row.
For multiple partitions, the IS creates separate caches for each partition.
Rank Port
Use to designate the column for which we want to rank values. We can designate only one Rank port in Rank transformation. The Rank port is an input/output port.
Rank Index Port
The designer automatically creates a RANKINDEX port for each rank transformation. The IS uses the Rankindex port to store the ranking position for each row in a group. It is an output port only.
Defining Groups
Like the Aggregator, the Rank transformation allows to group information.
à If two rank values match, they receive the same value in the rank index and the transformation skip the next value.
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