System for estimating a first access time of transactions accessing a database object

Abstract

A system and a computer readable medium for estimating the first access time of a plurality of currently active transactions accessing at least one database object is disclosed. According to varying embodiments of the system and computer readable medium disclosed herein, the present invention may provide an efficient mechanism for tracking the earliest first access time of the set of all currently active transactions accessing an object in a database system.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]Under 35 USC §120, this application is a continuation application and claims the benefit of priority to U.S. patent application Ser. No. 11 / 376,937, filed Mar. 15, 2006, entitled “METHOD AND SYSTEM FOR ESTIMATING A FIRST ACCESS TIME OF TRANSACTIONS ACCESSING A DATABASE OBJECT”, all of which is incorporated herein by reference.FIELD OF THE INVENTION[0002]The present invention relates to database management systems and more particularly to a system for estimating the earliest, or first access time for all currently active transactions accessing a database object.BACKGROUND OF THE INVENTION[0003]In a database system, the earliest point in time at which any currently active transaction first accessed a database object for read or write access may be desired to be tracked for a variety of reasons. For example, the earliest first write access time for any currently active transaction for an object, such as a table, table space, or object therei...

AI Technical Summary

Benefits of technology

This approach maintains accurate and non-stale CLSN values with reduced resource consumption, improving database system performance by conservatively approximating first access times and preventing adverse effects on system performance.

Problems solved by technology

Although tracking the CLSN values at a system level is possible, one of ordinary skill in the art will readily recognize that CLSN values maintained in such a conventional manner are prone to becoming stale.

For example, a single transaction that runs for days may result in a stale CLSN value that is quite old in comparison to remaining transactions accessing a different database object.

Consequently, processes that use this stale CLSN value may be less effective in performing their functions.

Consequently, if a conventional method that tracks CLSN values at the system level is used, a single long-running transaction may adversely affect performance of the entire database system.

Moreover, a particular transaction accessing a particular database object may also affect other transactions, including those which do not access the same database object.

This result of including system-level tracking is also undesirable.

Although conventional methods that maintain CLSN values using linked lists for each object may not suffer from stale CLSN values, other drawbacks persist.

In particular, these linked list-based methods for maintaining the conventional CLSN values for each object on the database system may consume substantial resources.

Because such conventional methods may have high overhead, such conventional methods may have a significant adverse impact on performance of the conventional databases system.

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