View | Details |
M_SAVEPOINT_STATISTICS | Global savepoint information per host and service |
M_SAVEPOINTS | Detailed information for individual savepoints |
M_SERVICE_THREADS M_SERVICE_THREAD_SAMPLES HOST_SERVICE_THREAD_SAMPLES | As of SAP HANA SPS 10 savepoint details are logged for THREAD_TYPE = 'PeriodicSavepoint' (see SAP Note 2114710). |
SQL statement | Details |
SQL: "HANA_IO_Savepoints" | Detailed information for individual savepoints |
SQL: "HANA_IO_Snapshots" | Snapshot information |
Sub phase | Thread detail | Description |
WaitForLock | enterCriticalPhase(waitForLock) | Before the critical phase is entered, a ConsistentChangeLock needs to be allocated by the savepoint. If this lock is held by other threads / transactions, the duration of this phase is increasing. At the same time all other modifications on the underlying table like INSERT, UPDATE or DELETE are blocked by the savepoint with ConsistentChangeLock. |
Critical | processCriticalPhase | Once the ConsistentChangeLock is acquired, the actual critical phase is entered and remaining I/O writes are performed in order to guarantee a consistent set of data on disk level. During this time other transactions aren't allowed to perform changes on the underlying table and are blocked with ConsistentChangeLock. |
Symptoms | Thread detail | Details |
Long waitForLock phase | enterCriticalPhase (waitForLock) | Long durations of the blocking phase (outside of the critical phase) are typically caused by SAP HANA internal lock contention. The following known scenarios exist ConsistentChangeLock Starting with Rev. 102 you can configure the following parameter in order to trigger a runtime dump (SAP Note 2400007) in case waiting for entering the critical phase takes longer than <seconds> seconds:indexserver.ini -> [persistence] -> runtimedump_for_blocked_savepoint_timeout = '<seconds>' (This is not a default parameter, add this parameter manually ) |
Long critical phase | processCriticalPhase | Delays during the critical phase are often caused by problems in the disk I/O area. |
SAVEPOINT_SHAREDLOCK_OWNERS | Owners of shared ConsistentChangeLock locks | In case a savepoint is blocked in the waitForLock phase (SAP Note 2100009), the blocking activities can be found in this section. |
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