SQL Server 2016 Telemetry Extended Event Session

By:Rajendra Gupta || Related Tips:More >Extended Events

Problem

In my previous tips SQL Server 2016 extended events detailed backup information and SQL Server restore steps with extended events we have seen how useful Extended Events are in SQL Server 2016. While exploring more on Extended Events I observed some new interesting events and in this tip we will explore these and see how they can be helpful.

Solution

Extended Events play an important role for troubleshooting issues and will replaceProfiler probably in an upcoming version of SQL Server. There are new Extended Events called telemetry_xevents in the Sessions folder in the Extended Events folder and it is enabled by default in SQL Server 2016.

As per Microsoft, most applications will include diagnostic features that generate custom monitoring and debugging information, especially when an error occurs. This is referred to as instrumentation and is usually implemented by adding event and error handling code to the application. The process of gathering remote information that is collected by instrumentation is usually referred to as telemetry.

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So let's explore these Extended Events.

SQL Server telemetry_xevents Extended Events

Microsoft has provided this new Extended Events Session to capture details around important events, errors that occurred and could help us to view what's happening with SQL Server at a high level in case of an issue.

So to see which events are being captured in this telemetry_xevents session, right click on the session and select Script Session As > Create To > New Query Editor Window. The following are the events that are part of this session:

CREATE EVENT SESSION [telemetry_xevents] ON SERVER
ADD EVENT qds.query_store_db_diagnostics,
ADD EVENT sqlserver.always_encrypted_query_count,
ADD EVENT sqlserver.auto_stats,
ADD EVENT sqlserver.column_store_index_build_low_memory,
ADD EVENT sqlserver.column_store_index_build_throttle,
ADD EVENT sqlserver.columnstore_delete_buffer_flush_failed,
ADD EVENT sqlserver.columnstore_delta_rowgroup_closed,
ADD EVENT sqlserver.columnstore_index_reorg_failed,
ADD EVENT sqlserver.columnstore_log_exception,
ADD EVENT sqlserver.columnstore_rowgroup_merge_failed,
ADD EVENT sqlserver.columnstore_tuple_mover_delete_buffer_truncate_timed_out,
ADD EVENT sqlserver.columnstore_tuple_mover_end_compress,
ADD EVENT sqlserver.data_masking_ddl_column_definition,
ADD EVENT sqlserver.data_masking_traffic,
ADD EVENT sqlserver.data_masking_traffic_masked_only,
ADD EVENT sqlserver.database_cmptlevel_change,
ADD EVENT sqlserver.database_created,
ADD EVENT sqlserver.database_dropped,
ADD EVENT sqlserver.error_reported(
WHERE ([severity]>=(20) OR ([error_number]=(18456) OR [error_number]=(17803) OR [error_number]=(701) OR [error_number]=(802) OR [error_number]=(8645) OR [error_number]=(8651) OR [error_number]=(8657) OR [error_number]=(8902) OR [error_number]=(41354) OR [error_number]=(41355) OR [error_number]=(41367) OR [error_number]=(41384) OR [error_number]=(41336) OR [error_number]=(41309) OR [error_number]=(41312) OR [error_number]=(41313)))),
ADD EVENT sqlserver.json_function_compiled(
ACTION(sqlserver.database_id)),
ADD EVENT sqlserver.missing_column_statistics,
ADD EVENT sqlserver.missing_join_predicate,
ADD EVENT sqlserver.query_memory_grant_blocking,
ADD EVENT sqlserver.rls_query_count,
ADD EVENT sqlserver.sequence_function_used(
ACTION(sqlserver.database_id)),
ADD EVENT sqlserver.server_memory_change,
ADD EVENT sqlserver.server_start_stop,
ADD EVENT sqlserver.stretch_database_disable_completed,
ADD EVENT sqlserver.stretch_database_enable_completed,
ADD EVENT sqlserver.stretch_database_reauthorize_completed,
ADD EVENT sqlserver.stretch_index_reconciliation_codegen_completed,
ADD EVENT sqlserver.stretch_remote_column_execution_completed,
ADD EVENT sqlserver.stretch_remote_column_reconciliation_codegen_completed,
ADD EVENT sqlserver.stretch_remote_index_execution_completed,
ADD EVENT sqlserver.stretch_table_alter_ddl,
ADD EVENT sqlserver.stretch_table_codegen_completed,
ADD EVENT sqlserver.stretch_table_create_ddl,
ADD EVENT sqlserver.stretch_table_data_reconciliation_results_event,
ADD EVENT sqlserver.stretch_table_hinted_admin_delete_event,
ADD EVENT sqlserver.stretch_table_hinted_admin_update_event,
ADD EVENT sqlserver.stretch_table_predicate_not_specified,
ADD EVENT sqlserver.stretch_table_predicate_specified,
ADD EVENT sqlserver.stretch_table_query_error,
ADD EVENT sqlserver.stretch_table_remote_creation_completed,
ADD EVENT sqlserver.stretch_table_row_migration_results_event,
ADD EVENT sqlserver.stretch_table_row_unmigration_results_event,
ADD EVENT sqlserver.stretch_table_unprovision_completed,
ADD EVENT sqlserver.stretch_table_validation_error,
ADD EVENT sqlserver.string_escape_compiled(
ACTION(sqlserver.database_id)),
ADD EVENT sqlserver.temporal_ddl_period_add,
ADD EVENT sqlserver.temporal_ddl_period_drop,
ADD EVENT sqlserver.temporal_ddl_schema_check_fail,
ADD EVENT sqlserver.temporal_ddl_system_versioning,
ADD EVENT sqlserver.temporal_dml_transaction_fail,
ADD EVENT sqlserver.window_function_used(
ACTION(sqlserver.database_id))
ADD TARGET package0.ring_buffer
WITH (MAX_MEMORY=4096 KB,EVENT_RETENTION_MODE=ALLOW_SINGLE_EVENT_LOSS,MAX_DISPATCH_LATENCY=120 SECONDS,MAX_EVENT_SIZE=0 KB,MEMORY_PARTITION_MODE=NONE,TRACK_CAUSALITY=OFF,STARTUP_STATE=ON)
GO

As we can see this Extended Event Session has START_STATE= ON that means even if you restart SQL Server, this Extended Event Session will automatically start up.

This contains a lot of Extended Events, so let's see what these are:

sqlserver.auto_stats: Occurs when index and column statistics are automatically updated. This event can be generated multiple times per statistics collection when the update is asynchronous. column_store_index_build_low_memory: Storage Engine detected a low memory condition and the rowgroup size was reduced. column_store_index_build_throttle: Shows the statistics of columnstore index build parallelism throttling. columnstore_delete_buffer_flush_failed: Columnstore delete buffer flush failed. columnstore_delta_rowgroup_closed: A delta rowgroup was closed. columnstore_index_reorg_failed: An Index Reorganize operation failed. columnstore_log_exception: Occurs when an exception occurs during processing for a columnstore operation. columnstore_rowgroup_merge_failed: A MERGE operation started merging columnstore rowgroups but failed in the process. columnstore_tuple_mover_delete_buffer_truncate_timed_out: Columnstore tuple mover truncate operation timed out due to an active snapshot transaction. columnstore_tuple_mover_end_compress: Columnstore tuple mover completed compressing a deltastore. data_masking_ddl_column_definition: Occurs when a data masking function is modified on a table column definition (ADD, CHANGE or DROP) data_masking_traffic: Occurs when data masking is applied to a query. data_masking_traffic_masked_only: Occurs when data masking is applied to a query and the query is actually masked. database_cmptlevel_change: Database compatibility level is changed. database_created database_dropped