Query Cost Model and Usage #9098
Description
This JIRA tracks building a mechanism for identifying and computing the indicative cost of a query, based on parameters such as query complexity and data statistics (cardinality, selectivity etc).
The cost model will be pluggable -- you just need to implement the interfaces.
The cost can be used for stuff like throttling and cancelling of expensive queries in the face of limited resource utilisation.
In a later stage, we can explore using the cost for a more intelligent query optimiser.
Note that this is more of a "logical" cost -- using statistics and query cyclomatic complexity.
Related work: #9055