DISABLE_HBASE_NUM_ROWS_ESTIMATE Query Option
Use the DISABLE_HBASE_NUM_ROWS_ESTIMATE query option to disable key
sampling of HBase tables in row count and row size estimation.
While generating a plan for an HBase query, the planner samples the underlying HBase
tables to estimate their row count and row size, and the sampling can negatively impact
the planning time. When the HBase table stats does not change much in short time, disable
the sampling by setting the DISABLE_HBASE_NUM_ROWS_ESTIMATE query option
to TRUE. And Impala planner will fall back to using Hive Metastore (HMS)
table stats instead.
When DISABLE_HBASE_NUM_ROWS_ESTIMATE query option is set to
TRUE, you need to update the HMS table stats by running COMPUTE
STATS. Alternatively, you can manually set table statistics by running
ALTER TABLE. See Table and Column Statistics
for details.
-
TRUEor1: Disables the normal key sampling of HBase tables and uses HMS table stats for estimation. -
FALSEor0: Enables the normal sampling of HBase tables.
Type: BOOLEAN
Default: FALSE