Explain lookup vs join vs merge in datastage?
|Used when joining large tables.||They are used while doing a range lookup within a small reference dataset.||Used when multiple updates and reject links are required within a dataset.|
|The performance of Join is increased while key-sorting data based on input links.||It does not require data on the input or the reference link to be sorted out.||It can have any number of input links, but it has to be matched with the number of reject links.|
|The key columns must be the same in the tables.||The Key column names do not have to be the same in the primary and lookup tables.||Here, to ensure minimum memory requirements, users have to ensure that rows having the same fundamental column values are located in the same portion and are divided by the same node.|
BY Best Interview Question ON 06 Jun 2020