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sys.dm_db_xtp_checkpoint_stats (Transact-SQL)

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Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance

Returns statistics about the In-Memory OLTP checkpoint operations in the current database. If the database has no In-Memory OLTP objects, sys.dm_db_xtp_checkpoint_stats returns an empty result set.

For more information, see In-Memory OLTP (In-Memory Optimization).

USE [In_Memory_db_name]
SELECT * FROM sys.dm_db_xtp_checkpoint_stats;

SQL Server 2014 (12.x) is substantially different from more recent versions, and is discussed separately.

The following table describes the columns in sys.dm_db_xtp_checkpoint_stats, for SQL Server 2016 (13.x) and later versions.

Column name Type Description
last_lsn_processed bigint Last LSN seen by the controller.
end_of_log_lsn numeric(38) The LSN of the end of log.
bytes_to_end_of_log bigint Log bytes unprocessed by the controller, corresponding to the bytes between last_lsn_processed and end_of_log_lsn.
log_consumption_rate bigint Rate of transaction log consumption by the controller (in KB/sec).
active_scan_time_in_ms bigint Time spent by the controller in actively scanning the transaction log.
total_wait_time_in_ms bigint Cumulative wait time for the controller while not scanning the log.
waits_for_io bigint Number of waits for log IO incurred by the controller thread.
io_wait_time_in_ms bigint Cumulative time spent waiting on log IO by the controller thread.
waits_for_new_log_count bigint Number of waits incurred by the controller thread for a new log to be generated.
new_log_wait_time_in_ms bigint Cumulative time spent waiting on a new log by the controller thread.
idle_attempts_count bigint Number of times the controller transitioned to an idle state.
tx_segments_dispatched bigint Number of segments seen by the controller and dispatched to the serializers. Segment is a contiguous portion of log that forms a unit of serialization. It is currently sized to 1 MB, but can change in future.
segment_bytes_dispatched bigint Total byte count of bytes dispatched by the controller to serializers, since the database restart.
bytes_serialized bigint Total count of bytes serialized since database restart.
serializer_user_time_in_ms bigint Time spent by serializers in user mode.
serializer_kernel_time_in_ms bigint Time spent by serializers in kernel mode.
xtp_log_bytes_consumed bigint Total count of log bytes consumed since the database restart.
checkpoints_closed bigint Count of checkpoints closed since the database restart.
last_closed_checkpoint_ts bigint Timestamp of the last closed checkpoint.
hardened_recovery_lsn numeric(38) Recovery starts from this LSN.
hardened_root_file_guid uniqueidentifier GUID of the root file that hardened as a result of the last completed checkpoint.
hardened_root_file_watermark bigint Internal Only. Specifies how far it is valid to read the root file up to (this is an internally relevant type only - called BSN).
hardened_truncation_lsn numeric(38) LSN of the truncation point.
log_bytes_since_last_close bigint Bytes from last close to the current end of log.
time_since_last_close_in_ms bigint Time since last close of the checkpoint.
current_checkpoint_id bigint Currently new segments are being assigned to this checkpoint. The checkpoint system is a pipeline. The current checkpoint is the one which segments from the log are being assigned to. Once it reaches a limit, the controller releases the checkpoint, and a new one created as current.
current_checkpoint_segment_count bigint Count of segments in the current checkpoint.
recovery_lsn_candidate bigint Internally Only. Candidate to be picked as recoverylsn when current_checkpoint_id closes.
outstanding_checkpoint_count bigint Number of checkpoints in the pipeline waiting to be closed.
closing_checkpoint_id bigint ID of the closing checkpoint.

Serializers are working in parallel, so once they finish, the checkpoint is a candidate for closing by close thread. But the close thread can only close one at a time and it must be in order, so the closing checkpoint is the one that the close thread is working on.
recovery_checkpoint_id bigint ID of the checkpoint to be used in recovery.
recovery_checkpoint_ts bigint Time stamp of recovery checkpoint.
bootstrap_recovery_lsn numeric(38) Recovery LSN for the bootstrap.
bootstrap_root_file_guid uniqueidentifier GUID of the root file for the bootstrap.
internal_error_code bigint Error seen by any of the controller, serializer, close, and merge threads.
bytes_of_large_data_serialized bigint Specifies the amount of data that was serialized.
db_in_checkpoint_only_mode bit True if database is in in-memory OLTP checkpoint-only mode.

Applies to: SQL Server 2022 (16.x) and later versions.

Permissions

SQL Server 2019 (15.x) and earlier versions require VIEW DATABASE STATE permission on the database.

SQL Server 2022 (16.x) and later versions, require VIEW DATABASE PERFORMANCE STATE permission on the database.

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