2010YOUY01 commented on PR #22704: URL: https://github.com/apache/datafusion/pull/22704#issuecomment-4627980368
> Subgroup What it varies (others held fixed) > `costsel` cost and selectivity point in different directions (expensive predicate is the selective one) > `cost` per-predicate cost, at equal selectivity > `selectivity` per-predicate selectivity, at equal cost > `cardinality` conjunct count `k = 2/4/8/16` > `width` string-column width (`PRED_FILL` = 2 / 30 / 170 chars) > `scale` row count `5k / 100k / 5M / 50M` > `neutral` predicates are interchangeable (equal cost, none selective) — an order-insensitive control > `correlation` conditional vs marginal selectivity (independent / positively / anti-correlated) > `drift` selectivity that changes across the scan > `nulls` null density (two- vs three-valued predicate results) Regarding the design: overall, I think it's great. In particular, I think it's important to test the `drift` dimension. One suggestion: `nulls` seem redundant here. Efficiently handling nulls is the responsibility of the `expr` evaluator. Within the scope of filter reordering, I think null density is at the same dimension as `selectivity` or `cost`, so we could remove it for simplicity. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
