Out of all optimisations, mapping optimisation is little tricky and it will take time to implement it.

Flat File

  1. Optimize line sequential buffer length. Default is 1024. Based on source we need to reduce it
  2. Must specify column delimiter in flat files
  3. Optimize proper cache for XML source

Single pass reading

  1. Always choose there is one SQ to load data into multiple target tables
  2. Choose Pass-through reading to improve performance

Filters

  1. Use SQ to filter the Source data
  2. Use Filter transformation
  3. Always use either of one to improve performance

Optimize data type conversions

  1. Use Integers, wherever required in Data comparisons like Lookup/Filter
  2. Use “DATE” data type as String to avoid any problem

Expression

  1. Remove unnecessary expressions
  2. Observe time difference, with/without expression transformation
  3. Reduce multiple Lookups
  4. Minimize Aggregates
  5. Instead of the same expressions, use Local Variables
  6. Use always integers
  7. Use DECODE instead of LOOKUP
  8. Use operators (Ex: instead of CONCAT … use || ||) instead of functions
  9. Optimize IIF function. Write it in simpler way.
  10. Run test mapping with/without expression. Identify bottlenecks.
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