Valery Popov <v.popov@postgrespro.ru> writes: > Recursive queries are typically used to deal with hierarchical or > tree-structured data. > In some conditions when data contain relationships with cycles recursive query will loop > unlimited and significantly slows the client's session.
The standard way of dealing with that is to include logic in the query to limit the recursion depth, for example
WITH RECURSIVE t(n) AS ( SELECT 1 UNION ALL SELECT n+1 FROM t WHERE n < 10 ) SELECT n FROM t;
I don't see an example of this technique in the documentation, which maybe is a documentation improvement opportunity. > To prevent "infinite" loop I suggest the max_recursion_depth parameter, > which defines the maximum recursion level during the execution of recursive > query.
Controlling this via a GUC is a seriously awful idea. We learned a long time ago to avoid GUCs that have a direct impact on query semantics; the scope of their effects is just about never what you want.
Also, there are already ways to constrain queries-gone-crazy; particularly statement_timeout, which has the advantage that it works for other types of badly-written queries not only this one.
isn't the recursive limits much more a resource limit like work_mem etc?
