Optimized count distinct...

[markp201]

I read about a technique to identify distinct field values.   Assuming SourceTable is loaded with carmodel field

DistinctCarmodel:

LOAD DISTINCT

  carmodel,

  Autonumber(carmodel) AS %Distinct_carmodel

RESIDENT

  SourceTable

With simple or complex set analysis, we can use

  count(%Distinct_carmodel)

or

max(%Distinct_camodel)

I tweaked this idea a bit with the following

DistinctCarmodel:

LOAD DISTINCT

  carmodel,

  Autonumber(carmodel,'distinctcarmodel') AS %Distinct_carmodel

RESIDENT

  TempSourceTable;

SourceTable:

LOAD

  carmodel,

  Autonumber(carmodel,'distinctcarmodel') AS %Distinct_carmodel

RESIDENT

  TempSourceTable;

DROP TABLE DistinctCarmodel;

The one difference is we would have to use

max(%Distinct_camodel)