Determines whether the prefetching optimization is applied during join query processing.
Type: numeric (0, 1)
or corresponding mnemonic strings (NONE, HT_BUCKET).
Default: 1 (equivalent to HT_BUCKET)
Added in: Impala 2.6.0
Usage notes:
The default mode is 1, which means that hash table buckets are prefetched during join query processing.
Related information:
Joins in Impala SELECT Statements, Performance Considerations for Join Queries.