====
---- 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
====