ENABLE_EXPR_REWRITES Query Option
The ENABLE_EXPR_REWRITES
query option controls whether to enable or
disable the query compile time optimizations. These optimizations rewrite the expression
trees to a more compact and optimized form that helps avoid redundant expression
evaluation at run time. Performance optimizations controlled by this query option include:
- Constant folding (added in )
- Extracting common conjuncts from disjunctions (added in )
- Simplify conditionals with constant conditions (added in )
Set the option to false
or 0
to disable the performance
optimizations.
Type: boolean
Default: true
(1
)
Added in: Impala 2.8