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.
TRUE or 1: Disables codegen.
FALSE or 0: Enables codegen.
Type: Boolean
Default: false (shown as 0 in output of SET
statement)