Chapter 1: Limiting Access to Server Resources

What are resource limits?

Adaptive Server provides resource limits to help System Administrators prevent queries and transactions from monopolizing server resources. Resource limits, however, are not fully specified until they are bound to a time-range.

A resource limit is a set of parameters specified by a System Administrator to prevent an individual login or application from exceeeding the limits described in Table 1-1.

**Table 1-1: Resource limits**
LIimit being tracked	What is tracked by Adaptive Server
Exceeding I/O costs	Estimated costs – as determined by the optimizer. Actual costs – as measured during query execution
Returning excessive number of rows	Tracked on a per-query basis
Exceeding a given elapsed time	On a query batch basis in a given transaction.
Utilizing excessive tempdb space	Tracked per session

Resource limits are bound to time-ranges, allowing the System Administrator to define precisely when they should be enforced.

The set of parameters for a resource limit includes the time of day to enforce the limit and the type of action to take. For example, you can prevent huge reports from running during critical times of the day, or kill a session whose query produces unwanted Cartesian products.

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