Sergei Petrunia added a comment - 2023-03-29 16:40 Note: starting from 10.5 and fix for MDEV-9750 , there other limits one can hit in the range optimizer. The optimizer makes a note in the trace when hitting them examples: "setup_range_conditions": [ { "enforce_sel_arg_weight_limit": { "index": "PRIMARY", "old_weight": 105600, "new_weight": 1560 } } ], "sel_arg_weight_heuristic": { "key1_field": "year_id", "key2_field": "location_id", "key1_weight": 30, "key2_weight": 3519 }

Sergei Petrunia added a comment - 2023-03-29 17:39 Johnston could you review this?

Sergei Petrunia added a comment - 2023-08-22 11:36 - edited MAX_SEL_ARGS is "the maximum number of SEL_ARG objects that may be allocated during range analysis" (range analysis is performed on a per-table basis) . MAX_SEL_ARGS is a #define in opt_range.cc, it is not visible to the user. max_sel_arg_weight is a user-visible variable. It is "the maximum weight of a SEL_ARG graph that the optimizer may construct". The definitions of SEL_ARG graph and its weight are rather convoluted. If the optimizer allocated N SEL_ARG objects, the SEL_ARG graph it constructed may have a weight that's less, equal, or greater than N.

Sergei Petrunia added a comment - 2023-08-22 11:42 Note: Optimizer trace will get these keywords for hitting the weight limit: sel_arg_weight_heuristic enforce_sel_arg_weight_limit The patch for this MDEV added: sel_arg_alloc_limit_hit

Sergei Petrunia added a comment - 2023-08-22 11:51 - edited Summary for documentation: The optimizer may cause high memory usage or long processing time when analyzing complex WHERE clauses. It has multiple limits which tell it to short-cut the analysis if it gets too time and/or memory intensive. One of these limit is MAX_SEL_ARGS constant which is a #define in the source code. After this bugfix, the optimizer will write a sel_arg_alloc_limit_hit record in the Optimizer Trace when it hits the MAX_SEL_ARGS limitation.