Understanding Query of Queries performance

Query of Queries performs very well on single-table query objects that were accessed directly from a database. This is because ColdFusion MX stores meta information for a query object accessed from a database.

When working with a query resulting in a SQL join, Query of Queries performs as follows:

• Query of Queries is very efficient for simple joins in which there is only one equality between two column references or constants; for example:

  SELECT T1.a, b, c, d FROM T1, T2 WHERE T1.a = T2.a
  

• Query of Queries is less efficient for joins in which the predicate contains multiple expressions; for example:

  SELECT T1.a, b, c, d FROM T1, T2 
  WHERE T1.a = T2.a AND T1.b + T1.c = T2.b + T2.c
  

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