| ==== |
| ---- QUERY |
| # IMPALA-11068: without tuning hdfs_scanner_non_reserved_bytes, this query can launch |
| # up to 3 threads (with hdfs_scanner_thread_max_estimated_bytes default to 32MB). |
| set num_nodes=1; |
| set mem_limit=130m; |
| set debug_action="HDFS_SCANNER_THREAD_OBTAINED_RANGE:SLEEP@500"; |
| select count(*) from tpch_parquet.lineitem where l_comment = 'telets. quickly '; |
| ---- RESULTS: |
| 4 |
| ---- RUNTIME_PROFILE |
| aggregation(SUM, NumScannerThreadsStarted): 3 |
| ==== |
| ---- QUERY |
| # IMPALA-11068: raising hdfs_scanner_non_reserved_bytes above compressed_text_est_bytes |
| # will reduce NumScannerThreadsStarted. |
| set num_nodes=1; |
| set mem_limit=130m; |
| set debug_action="HDFS_SCANNER_THREAD_OBTAINED_RANGE:SLEEP@500"; |
| set hdfs_scanner_non_reserved_bytes=48m; |
| select count(*) from tpch_parquet.lineitem where l_comment = 'telets. quickly '; |
| ---- RESULTS: |
| 4 |
| ---- RUNTIME_PROFILE |
| aggregation(SUM, NumScannerThreadsStarted): 2 |
| ==== |
| ---- QUERY |
| # IMPALA-11068: high hdfs_scanner_non_reserved_bytes does not impact the first scanner |
| # thread. |
| set num_nodes=1; |
| set mem_limit=130m; |
| set debug_action="HDFS_SCANNER_THREAD_OBTAINED_RANGE:SLEEP@500"; |
| set hdfs_scanner_non_reserved_bytes=64m; |
| select count(*) from tpch_parquet.lineitem where l_comment = 'telets. quickly '; |
| ---- RESULTS: |
| 4 |
| ---- RUNTIME_PROFILE |
| aggregation(SUM, NumScannerThreadsStarted): 1 |
| ==== |