User quotas in Admission Control (Preview)
User quotas in Impala’s Admission Control set per-user query limits to ensure fair resource distribution and prevent system overload.
Starting with Cloudera Runtime 7.3.1.500 SP3, user quotas introduce rules to restrict the number of queries a users/groups can run concurrently. These rules apply at both the pool and root levels and can be based on individual usernames, wildcard users, or user groups. Queries are counted against limits starting with admission control acceptance and continuing until they are released.
When a query exceeds the defined quota, it is rejected at submission time.
User quota configuration elements
List of XML elements used to configure user quotas in Impala’s Admission Control.
| Element | Element |
|---|---|
| userQueryLimit | Used to define a User or Wildcard Rule |
| totalCount | Used to define a Group Rule |
| totalCount | Used to define the number of queries that can run concurrently. |
| user | Used to specify a username to define a User Rule, or, by using the wildcard '*', to define a Wildcard Rule. |
| group | In a Group rule, used to specify a group name that the rule applies to. |
Rule precedence:
- User rules override group and wildcard rules
- Group rules override wildcard rules.
- Pool-level rules are evaluated first; if passed, root-level rules are checked.
- If a user belongs to multiple groups, the least restrictive rule applies.
