Parse trees are always presented upside down, so query
execution begins with the lower cluster of operations and terminates with the upper cluster. In an EXPLAIN of query, the expressions in the upper cluster would be referred to as residual conditions.
execution begins with the lower cluster of operations and terminates with the upper cluster. In an EXPLAIN of query, the expressions in the upper cluster would be referred to as residual conditions.
EXPLAIN wording, "residual conditions" would be any additional filtering (beyond the join terms, or index access criteria, etc.) that will be applied "on the fly" during THIS step - further limiting the rows put into spool and passed along to subsequent steps.In other words, which of the remaining (residual) conditions can be applied NOW rather than waiting until a later step.
ReplyDeleteSource : http://krishtechforum.blogspot.sg/2013/06/meaning-of-residual-condition-in.html