In database management systems, block contention (or data contention) refers to multiple processes or instances competing for access to the same index or data
block
Block or blocked may refer to:
Arts, entertainment and media Broadcasting
* Block programming, the result of a programming strategy in broadcasting
* W242BX, a radio station licensed to Greenville, South Carolina, United States known as ''96.3 ...
at the same time. In general this can be caused by very frequent index or table scans, or frequent updates. Concurrent statement executions by two or more instances may also lead to contention, and subsequently
busy waiting
In computer science and software engineering, busy-waiting, busy-looping or spinning is a technique in which a process repeatedly checks to see if a condition is true, such as whether keyboard input or a lock is available. Spinning can also be use ...
for the process without the
lock
Lock(s) may refer to:
Common meanings
*Lock and key, a mechanical device used to secure items of importance
*Lock (water navigation), a device for boats to transit between different levels of water, as in a canal
Arts and entertainment
* ''Lock ...
.
Solutions
*To reduce contention for table blocks due to delete, select or update statements, reduce the number of rows per block. This can be done by using a smaller block size.
*To reduce contention for table blocks due to insert statements, increase the number of freelists, or buffer frames.
*To reduce contention for index blocks the best strategy is to implement a
reverse index
Database management systems provide multiple types of indexes to improve performance and data integrity across diverse applications. Index types include b-trees, bitmaps, and r-trees.
In database management systems, a reverse key index strategy r ...
.
In most situations the goal is to spread queries over a greater number of blocks, to avoid concentrating on any single one.
References
Database management systems
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