Checkpoint (_Checkpoint)

The _Checkpoint VST displays information about each checkpoint, including the checkpoint number and beginning time, the time required to complete the checkpoint, and the number of modified buffers scheduled to be written. The file also describes APW-written buffers.

Field name Data type Description
_Checkpoint-ApwQ INT64 Number of buffers written by the APW queue and replaced on the least recently used (LRU) chain by APWs
_Checkpoint-Bi-Writes INTEGER The number of BI buffers written to disk at checkpoint end
_Checkpoint-Bi-Write-Time DECIMAL Time in seconds to write the BI buffers at checkpoint end
_Checkpoint-Buffers INT64 The number of database buffers checkpointed
_Checkpoint-Cluster INT64 The checkpoint current BI cluster number
_Checkpoint-CptQ INT64 Number of buffers written from the checkpoint queue by the APWs
_Checkpoint-B-Write-Time DECIMAL Time in seconds to write the buffers from the database buffer pool at checkpoint end
_Checkpoint-Dirty INT64 Number of modified buffers scheduled to be written
_Checkpoint-Duration DECIMAL The time to do the housekeeping of the checkpoint. This includes the time to write the active recovery log buffers to disk, write any outstanding dirty buffers marked at the previous checkpoint, scan the database buffer pools for dirty buffers marking them as needing to be written to disk prior to the start of the next check point (putting them on the checkpoint queue) and to perform the file system synchronization (_Checkpoint-SyncTime)
_Checkpoint-Flush INT64 Number of database buffers written at the end of the checkpoint
_Checkpoint-Len CHARACTER The timestamp value reporting the time the checkpoint completed. The checkpoint is not considered completed until all dirty buffers on the checkpoint queue have been written out. This is either done over time by the APWs between checkpoints or is forced at the next checkpoint (buffers flushed at checkpoint). The datetime displays in the format Thu Dec 23 16:24:20 2021.
_Checkpoint-Len-TZ TIMESTAMP The timestamp value reporting the time the checkpoint completed. The checkpoint is not considered completed until all dirty buffers on the checkpoint queue have been written out. This is either done over time by the APWs between checkpoints or is forced at the next checkpoint (buffers flushed at checkpoint).The datetime displays in datetime-tz format, for example, 12/23/2021 16:24:20.881-05:00.
_Checkpoint-Number INT64 The number of this checkpoint
_Checkpoint-Scan INT64 Number of buffers written by the APWs during the scan cycle
_Checkpoint-SyncTime DECIMAL The time to perform the file system synchronization of the checkpoint. (fdatasync() on UNIX systems, FlushFileBuffers() on Windows systems)
_Checkpoint-Time CHARACTER Time the checkpoint began. The datetime displays in the format Thu Dec 23 16:24:20 2021.
_Checkpoint-Time-TZ TIMESTAMP Time the checkpoint began. The datetime displays in datetime-tz format, for example, 12/23/2021 16:24:20.881-05:00.
_Checkpoint-B-Flush- Waits INT64 Number of dirty buffers in the writing state that are being waited for at a checkpoint.
_Checkpoint-B-Flush- Wait-Time DECIMAL Total wait time, measured in seconds, at the current checkpoint for dirty buffers to transition from the changed or writing state.