Ted Xu created CALCITE-1933:
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Summary: Cost estimation for expression evaluate
Key: CALCITE-1933
URL: https://issues.apache.org/jira/browse/CALCITE-1933
Project: Calcite
Issue Type: New Feature
Reporter: Ted Xu
Assignee: Julian Hyde
Expression evaluate performance is different one to another based on its
operator type and underlying execution engine. For example, a regex pattern
matching (e.g., col like 'foo%bar%') may requires 100 times more cost compares
to a simple comparison (e.g., col > 3). Currently we don't have this kind of
differentiation.
Expression cost will grant following applications:
1. Improved predicate push down: predicates can be pushed down to the right
position based on row count and its own cost.
2. Predicate ordering rule: predicate with different order, e.g.,
{code:sql}
col1 like 'foo%bar%' and col2 > 3
col2 > 3 and col1 like 'foo%bar%'
{code}
may have different performance, introducing a predicate ordering rule will help
find a better one.
The cost of each RexCall / RexAggCall is provided by Schema, stored in an
external metadata service.
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