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03/24/15 Checkpoints
17:50:12 Ckpt --------- Database Writes ---------- ------ Performance Timings --------- No. Time Len Freq Dirty CPT Q Scan APW Q DB Writes Bi Writes Duration Sync Time DB Write Bi Write NumChkpt 56 17:50:07 49 0 24 0 0 0 0 19 0.02 0.00 0.00 0.01 13 55 17:50:07 0 0 27 0 0 0 13 19 0.02 0.00 0.00 0.01 14 54 17:50:03 4 4 21 0 0 0 14 19 0.02 0.00 0.00 0.02 7 53 17:50:03 0 0 22 0 0 0 7 19 0.02 0.01 0.00 0.02 15 52 17:50:02 1 1 32 0 0 0 15 19 0.03 0.00 0.00 0.02 17 51 17:49:14 48 48 30 0 0 0 17 9 0.01 0.00 0.00 0.01 13 50 17:49:07 7 7 17 0 0 0 13 19 0.02 0.00 0.00 0.01 4 49 17:49:06 1 1 24 0 0 0 4 19 0.02 0.00 0.00 0.01 20 Enter <return>, R, U, P, T, or X (? for help): |
Ckpt. No. — The sequential number assigned to the checkpoint
Time — The time the checkpoint began
Len — The length of time required to complete the checkpoint. 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 (DB Writes).
Freq — The length of time between checkpoint starts
Dirty — The number of modified buffers scheduled to be written
Database Writes
CPT Q — The number of buffers written from the checkpoint queue by the APWs
Scan — The number of buffers written by the APWs during the scan cycle
APW Q — The number of buffers written by the APW queue and replaced on the least recently used (LRU) chain by APWs
DB Writes — The total number of database buffers written all at once at the end of the checkpoint
Bi Writes — The total number of BI buffers written from the BI buffer pool all at once at the end of the checkpoint
Performance Timings
Duration — 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 (Sync Time).
Sync Time — The time to perform the file system synchronization of the checkpoint (fdatasync() on UNIX, FlushFileBuffers() in Windows)
DB Write — The time in seconds to scan and write the buffers from the database buffer pool
Bi Write — The time in seconds to write the buffers from the -bibufs buffer pool
NumChkpt — The number of buffers checkpointed (written from the database buffer pool)