MQE: add tests for common subexpression elimination for expressions with multiple children, and add metric on number of selectors eliminated #11879
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…ith multiple children
56quarters
approved these changes
Jun 27, 2025
| @@ -50,7 +55,7 @@ func (e *OptimizationPass) Apply(_ context.Context, plan *planning.QueryPlan) (* | |||
| paths := e.accumulatePaths(plan) | |||
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| // For each path: find all the other paths that terminate in the same selector, then inject a duplication node | |||
| err := e.groupAndApplyDeduplication(paths, 0) | |||
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Stylistic choice but: If the groupAndApplyDeduplication() method was changed to return a count of the number of selectors eliminated, we could remove the "have eliminated" boolean and increment the metric here single time. I don't feel strongly either way.
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Good idea. How's #11900?
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Given the approval, I'm going to merge this as-is so it's part of this week's release while we discuss #11879 (comment) |
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charleskorn
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Jun 30, 2025
… "selectors inspected" metric (#11900) #### What this PR does This PR builds on #11879, addressing #11879 (comment) and adding an additional "selectors inspected" metric. #### Which issue(s) this PR fixes or relates to #11879 #### Checklist - [x] Tests updated. - [n/a] Documentation added. - [covered by #10067] `CHANGELOG.md` updated - the order of entries should be `[CHANGE]`, `[FEATURE]`, `[ENHANCEMENT]`, `[BUGFIX]`. If changelog entry is not needed, please add the `changelog-not-needed` label to the PR. - [n/a] [`about-versioning.md`](https://github.com/grafana/mimir/blob/main/docs/sources/mimir/configure/about-versioning.md) updated with experimental features.
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What this PR does
This PR makes two changes to common subexpression elimination:
cortex_mimir_query_engine_common_subexpression_elimination_duplication_nodes_introducedmetric is useful for gauging the impact of CSE, but doesn't tell us how much load on ingesters and store-gateways we've avoided. The new metric tells us the number of selectors eliminated and therefore gives us a better idea of the number of avoided ingester and store-gateway requests.Which issue(s) this PR fixes or relates to
#11189
Checklist
CHANGELOG.mdupdated - the order of entries should be[CHANGE],[FEATURE],[ENHANCEMENT],[BUGFIX]. If changelog entry is not needed, please add thechangelog-not-neededlabel to the PR.about-versioning.mdupdated with experimental features.