The priority of writing dirty pages to the disk increases as the time and the amount of work since the last checkpoint grows.

The database engine is running without a transaction log and a transaction is committed.

A transaction issues a CHECKPOINT statement.

The database engine is idle long enough to write all dirty pages.

The estimated time to do a recovery operation exceeds the database option RECOVERY_TIME.

The amount of time since the last checkpoint exceeds the database option CHECKPOINT_TIME.

Reasons for a checkpointĪ checkpoint can occur for several reasons: Once all dirty pages are written to disk, the checkpoint log is deleted. A checkpoint is a point at which all dirty pages are written to disk. For improved performance, they are cached in memory and written to disk when the cache is full or the server has no pending requests. The copied pages are the checkpoint log.ĭirty pages are not written immediately to the disk. Before a page is updated (made dirty), a copy of the original is always made. The checkpoint log is used during database recovery after a system failure or improper shutdown of the database engine.Ī SQL Anywhere database file is composed of pages. The checkpoint log Checkpoint log purpose Optionally, you can maintain a mirror of the transaction log for greater protection of vital data.

Each log exists for each database running on a database engine or server. SQL Anywhere uses three logs to protect your data from system and media failure.Īll these logs play a role in data recovery.

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