17 July 2009

DBMS: Checkpoint (Definitions)

"The point at which all data pages that have been changed are guaranteed to have been written to the database device." (Karen Paulsell et al, "Sybase SQL Server: Performance and Tuning Guide", 1996)

"Issued at intervals to run through the transaction log and verify that all committed transactions at that point are physically written back to the database." (Owen Williams, "MCSE TestPrep: SQL Server 6.5 Design and Implementation", 1998)

"An event in which the database engine writes dirty buffer pages to disk. Dirty pages are pages that have been modified, but the modifications have not yet been written to disk. Each checkpoint writes to disk all pages that were dirty at the last checkpoint and still have not been written to disk. Checkpoints occur periodically based on the number of log records generated by data modifications, or when requested by a user or a system shutdown." (Anthony Sequeira & Brian Alderman, "The SQL Server 2000 Book", 2003)

"This is an entry that SQL Server records in a transaction log when it copies transactions from the log to the datafile." (Joseph L Jorden & Dandy Weyn, "MCTS Microsoft SQL Server 2005: Implementation and Maintenance Study Guide - Exam 70-431", 2006)

"An event in which the database engine writes pages that have been modified, but the modifications have not yet been written to disk. Checkpoints can occur periodically based on the number of log records generated by data modifications or when requested by a user or a system shutdown. A point that you can return to directly if the package should fail past that point. Complex packages will often have multiple checkpoints to reduce the amount of work that will need to be redone if a failure occurs." (Victor Isakov et al, "MCITP Administrator: Microsoft SQL Server 2005 Optimization and Maintenance (70-444) Study Guide", 2007)

"An event in which the Database Engine writes dirty buffer pages to disk. Each checkpoint writes to disk all the pages that were dirty at the last checkpoint and still have not been written to disk." (Microsoft, "SQL Server 2012 Glossary", 2012)

"The process of storing a set of data or system state that is in a known consistent or safe state so that it can be later restored by a rollback operation if the system fails or the data is corrupted." (O Sami Saydjari, "Engineering Trustworthy Systems: Get Cybersecurity Design Right the First Time", 2018)

"A point at which the database manager records internal status information in the log; the recovery process uses this information if the subsystem abnormally terminates." (Sybase, "Open Server Server-Library/C Reference Manual", 2019)

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