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45995e6892
Defines SystemTable which are in-memory tables that can provide access to Impala state. Adds the 'impala_query_live' to the database 'sys', which already exists for 'sys.impala_query_log'. Implements the 'impala_query_live' table to view active queries across all coordinators sharing the same statestore. SystemTables create new SystemTableScanNodes for their scan node implementation. When computing scan range locations, SystemTableScanNodes creates a scan range for each in the cluster (identified via ClusterMembershipMgr). This produces a plan that looks like: Query: explain select * from sys.impala_query_live +------------------------------------------------------------+ | Explain String | +------------------------------------------------------------+ | Max Per-Host Resource Reservation: Memory=4.00MB Threads=2 | | Per-Host Resource Estimates: Memory=11MB | | WARNING: The following tables are missing relevant table | | and/or column statistics. | | sys.impala_query_live | | | | PLAN-ROOT SINK | | | | | 01:EXCHANGE [UNPARTITIONED] | | | | | 00:SCAN SYSTEM_TABLE [sys.impala_query_live] | | row-size=72B cardinality=20 | +------------------------------------------------------------+ Impala's scheduler checks for whether the query contains fragments that can be scheduled on coordinators, and if present includes an ExecutorGroup containing all coordinators. These are used to schedule scan ranges that are flagged as 'use_coordinator', allowing SystemTableScanNodes to be scheduled on dedicated coordinators and outside the selected executor group. Execution will pull data from ImpalaServer on the backend via a SystemTableScanner implementation based on table name. In the query profile, SYSTEM_TABLE_SCAN_NODE includes ActiveQueryCollectionTime and PendingQueryCollectionTime to track time spent collecting QueryState from ImpalaServer. Grants QueryScanner private access to ImpalaServer, identical to how ImpalaHttpHandler access internal server state. Adds custom cluster tests for impala_query_live, and unit tests for changes to planner and scheduler. Change-Id: Ie2f9a449f0e5502078931e7f1c5df6e0b762c743 Reviewed-on: http://gerrit.cloudera.org:8080/20762 Reviewed-by: Jason Fehr <jfehr@cloudera.com> Reviewed-by: Riza Suminto <riza.suminto@cloudera.com> Tested-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>