Filtering_filter

This filter should check any record received from the input connector, and should then send the records that match a specified connector to the output connector. This filter should have a single input connector. Filter will be used for the SELECT, WHERE and HAVING statements.

Algorithm

Operation algorithm is the same as algorithm B of [Select_filter], except that records are read from the input connector instead of being read from database.

Filter could choose algorithm A of [Select_filter] only if data from input connector is already sorted (this should be checked on cost calculation results received from input connector)

This filter does not support seek message. If the filter receive such a message, it should redirect the message to the input connector (message will then be threaded by the next filter)

Cost calculation

Operation cost of this filter is 0, as this filter does not do any additional I/O operation.

Expected number of record calculation should be same as the table filter.

See also

[Set_engine]