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