The DISABLE_CODEGEN is a debug option, and it's used to work around any issues with Impala's runtime code generation. If a query fails with an "illegal instruction" or other hardware-specific message, try setting DISABLE_CODEGEN=true and running the query again. If the query succeeds only when the DISABLE_CODEGEN option is turned on, submit the problem to the appropriate support channel and include that detail in the problem report.

Most queries will run significantly slower with DISABLE_CODEGEN=true.

In Impala 2.10 and higher, the DISABLE_CODEGEN_ROWS_THRESHOLD optimisation automatically disables codegen for small queries because short-running queries may run faster without the overhead of codegen.

The following values are supported:
  • TRUE or 1: Disables codegen.
  • FALSE or 0: Enables codegen.

Type: Boolean

Default: false (shown as 0 in output of SET statement)