Bug(LogQL): Fix mismatch results on scalar and vector binary ops
#10997
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Repect the Promql following behaviour of Binary operations with vector vs scalar 1. `scalar` op `vector` - vector 2. `vector` op `scalar` - vector Signed-off-by: Kaviraj <[email protected]>
Signed-off-by: Kaviraj <[email protected]>
Signed-off-by: Kaviraj <[email protected]>
Signed-off-by: Kaviraj <[email protected]>
kavirajk
changed the title
scalar and vector binary opsscalar and vector binary ops
Signed-off-by: Kaviraj <[email protected]>
owen-d
reviewed
Oct 26, 2023
pkg/logql/syntax/ast.go
Outdated
| // This matters because, either it's (vector op scalar) or (scalar op vector), the return sample value should | ||
| // always be sample value of vector argument. | ||
| // https://github.com/grafana/loki/issues/10741 | ||
| func MergeBinOp(op string, left, right *promql.Sample, swap, notReturnBool, isVectorComparison bool) (*promql.Sample, error) { |
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I think it's more confusing to use notReturnBool compared to filter.
pkg/logql/syntax/ast.go
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| // if a filter-enabled vector-wise comparison has returned non-nil, | ||
| // ensure we return the left hand side's value (2) instead of the | ||
| // comparison operator's result (1: the truthy answer) | ||
| if notReturnBool { |
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The bool flag doesn't have anything to do with whether we should perform swap. For an example, try 1 < bool $METRIC in prometheus -- it'll return a vector of values with 0 or 1.
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I think it's been there because, swapping has no impact when return bool (vector of 0 or 1)
Means, both
1 < bool $METRIC and $METRIC > bool 1 will return exact same vector of values (0 or 1) without needed to swap. In other words, whether to return left or right sample is irrelevant in case of returning bool. Am I missing anything here?
Also confirmed by moving the swap out of filter check. Added extra test to lock the behaviour.
1. revert `notReturnBool` -> `filter` 2. swap independent of `filter` flag Signed-off-by: Kaviraj <[email protected]>
Signed-off-by: Kaviraj <[email protected]>
owen-d
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Oct 27, 2023
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Oct 27, 2023
Changlog to include this LogQL binary ops bug fix. #10997 Signed-off-by: Kaviraj <[email protected]>
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Apr 12, 2024
…rafana#10997) **What this PR does / why we need it**: [According to LogQL doc,](https://grafana.com/docs/loki/latest/query/#comparison-operators) binary operators between `scalar` and `vector` should behave as follows (either it's `scalar` op `vector` or `vector` op `scalar`) ``` Between a vector and a scalar, these operators are applied to the value of every data sample in the vector ``` PromQL (where LogQL inspired from) [also works that way](https://prometheus.io/docs/prometheus/latest/querying/operators/). Currently LogQL violates this behaviour. It returns whatever on the `left` (even if it's scalar). Look into the attached issue for more details. Changes: 1. Fixed `MergeBinOps` by making it aware when to return left or right (depending on which is from vector originally) 2. Add tests in both `engine_test.go` and `evaluator_test.go` to lock this behaviour 3. Added appropriate comments to the types and functions. **Which issue(s) this PR fixes**: Fixes grafana#10741 **Special notes for your reviewer**: **Checklist** - [x] Reviewed the [`CONTRIBUTING.md`](https://github.com/grafana/loki/blob/main/CONTRIBUTING.md) guide (**required**) - [x] Tests updated - [ ] `CHANGELOG.md` updated - [ ] If the change is worth mentioning in the release notes, add `add-to-release-notes` label - [ ] Changes that require user attention or interaction to upgrade are documented in `docs/sources/setup/upgrade/_index.md` - [ ] For Helm chart changes bump the Helm chart version in `production/helm/loki/Chart.yaml` and update `production/helm/loki/CHANGELOG.md` and `production/helm/loki/README.md`. [Example PR](grafana@d10549e) - [ ] If the change is deprecating or removing a configuration option, update the `deprecated-config.yaml` and `deleted-config.yaml` files respectively in the `tools/deprecated-config-checker` directory. <!-- TODO(salvacorts): Add example PR --> --------- Signed-off-by: Kaviraj <[email protected]>
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What this PR does / why we need it:
According to LogQL doc, binary operators between
scalarandvectorshould behave as follows (either it'sscalaropvectororvectoropscalar)PromQL (where LogQL inspired from) also works that way.
Currently LogQL violates this behaviour. It returns whatever on the
left(even if it's scalar). Look into the attached issue for more details.Changes:
MergeBinOpsby making it aware when to return left or right (depending on which is from vector originally)engine_test.goandevaluator_test.goto lock this behaviourWhich issue(s) this PR fixes:
Fixes #10741
Special notes for your reviewer:
Checklist
CONTRIBUTING.mdguide (required)CHANGELOG.mdupdatedadd-to-release-noteslabeldocs/sources/setup/upgrade/_index.mdproduction/helm/loki/Chart.yamland updateproduction/helm/loki/CHANGELOG.mdandproduction/helm/loki/README.md. Example PRdeprecated-config.yamlanddeleted-config.yamlfiles respectively in thetools/deprecated-config-checkerdirectory.