When an abstract plan is saved, all white space (returns, tabs, and multiple spaces) in the query is trimmed to a single space, and a hash-key value is computed for the white-space trimmed SQL statement. The trimmed SQL statement and the hash key are stored in sysqueryplans along with the abstract plan, a unique plan ID, the user’s ID, and the ID of the current abstract plan group.
When abstract plan association is enabled, the hash key for incoming SQL statements is computed, and this value is used to search for the matching query and abstract plan in the current association group, with the corresponding user ID. The full association key of an abstract plans consists of:
The user ID of the current user
The group ID of the current association group
The full query text
Once a matching hash key is found, the full text of the saved query is compared to the query to be executed, and used if it matches.
The association key combination of user ID, group ID and query text means that for a given user, there cannot be two queries in the same abstract plan group that have the same query text, but different query plans.