@fpetkovski Can you review it once? If any changes required please let me know.

@yeya24 I have made changes as you suggested. Can you review it. Thank you in advanced.

Please include 2 test cases for absent. One is calling absent when the queried series is present, one is not. I see you only have the case of absent.

And please fix the test, test failure seems related.

@yeya24 I fixed errors. Can you please review it? Thank you.

Looks like tests are still failing. You can run make test to reproduce the failures.

ok

`
"sort": func(f FunctionArgs) promql.Sample {
if len(f.Points) == 0 {
return InvalidSample
}

sortedPoints := make([]promql.Point, len(f.Points))
copy(sortedPoints, f.Points)
sort.Slice(sortedPoints, func(i, j int) bool {
	return sortedPoints[i].V < sortedPoints[j].V
})

sortedValues := make([]float64, len(sortedPoints))
for i, point := range sortedPoints {
	sortedValues[i] = point.V
}

return promql.Sample{
	Metric: f.Labels,
	Point: promql.Point{
		T: f.StepTime,
		V: sortedValues,
	},
}

},
`
@fpetkovski @yeya24 In this implementation of sort, sortedPoints is of type []promql.Point and sortedValues is of type []float64. In final return statement, the V field of promql.Point is assigned a []float64 type which is not allowed as V is of type float64. To solve this issue, I modified Point struct to have a slice of float64 instead of a single float64 value for V but did not work. I do not understand while testing it provide me error as can't use sortedValues (variable of type []float64) as type float64 in struct literal. Can you give me some pointers on this?

I prefer to not modify the existing struct but have a separate operator to deal with sort and sort desc.

Let's focus on absent in this pr and fix tests first.

@yeya24 According prometheus query function documentation I have done changes in test cases. absent function used for alerting on when no time series exist for a given metric name and label combination.

In TestQueriesAgainstOldEngine -

{
    name: "absent with non-present metric",
    load: "",
    query: "absent(dummy_metric)",
    start: time.Unix(0, 0),
    end: time.Unix(3000, 0),
    step: 10 * time.Second,
},
{
    name: "absent with non-present label",
    load: `load 30s
        http_requests_total{pod="nginx-1", series="1"} 1+1.1x40
        http_requests_total{pod="nginx-2", series="1"} -10+1x50`,
    query: "absent(http_requests_total{pod=\"nginx-3\"})",
    start: time.Unix(0, 0),
    end: time.Unix(3000, 0),
    step: 10 * time.Second,
},
{
    name: "absent with present metric and label",
    load: `load 30s
        http_requests_total{pod="nginx-1", series="1"} 1+1.1x40
        http_requests_total{pod="nginx-2", series="1"} -10+1x50`,
    query: "absent(http_requests_total{pod=\"nginx-1\"})",
    start: time.Unix(0, 0),
    end: time.Unix(3000, 0),
    step: 10 * time.Second,
},

In TestInstantQuery -

{
    name: "absent with non-present metric",
    load: "",
    query: "absent(dummy_metric)",
    queryTime: time.Unix(50, 0),
    sortByLabels: true,
},
{
    name: "absent with non-present label",
    load: `load 30s
        http_requests_total{pod="nginx-1", series="1"} 1+1.1x40
        http_requests_total{pod="nginx-2", series="1"} -10+1x50`,
    query: "absent(http_requests_total{pod=\"nginx-3\"})",
    queryTime: time.Unix(50, 0),
    sortByLabels: true,
},
{
    name: "absent with present metric and label",
    load: `load 30s
        http_requests_total{pod="nginx-1", series="1"} 1+1.1x40
        http_requests_total{pod="nginx-2", series="1"} -10+1x50`,
    query: "absent(http_requests_total{pod=\"nginx-1\"})",
    queryTime: time.Unix(50, 0),
    sortByLabels: true,
},

But while running test found errors which indicate that the expected and actual results are not matching for the tests. Can you help me to understand what are my mistakes to fixed errors. I mentioned my errors are -

RUN TestInstantQuery/disableOptimizers=false/absent_with_non-
present_metric#01/disableFallback=false

testutil.go:91: engine_test.go:2586: ""
exp: &promql.Result{Err:error(nil),
Value:promql.Vector{promql.Sample{Point:promql.Point{T:50000, V:1, H:(*histogram.FloatHistogram)
(nil)}, Metric:labels.Labels{}}}, Warnings:storage.Warnings(nil)}
got: &promql.Result{Err:error(nil), Value:promql.Vector{}, Warnings:storage.Warnings(nil)}
Diff:
--- Expected
+++ Actual
@@ -1,2 +1,2 @@
-(*promql.Result)({} => 1 @[50000])
+(*promql.Result)()

=== RUN TestInstantQuery/disableOptimizers=false/absent_with_non-
present_label#01/disableFallback=true

testutil.go:91: engine_test.go:2586: ""
exp: &promql.Result{Err:error(nil),
Value:promql.Vector{promql.Sample{Point:promql.Point{T:50000, V:1, H:(*histogram.FloatHistogram)
(nil)}, Metric:labels.Labels{labels.Label{Name:"pod", Value:"nginx-3"}}}},
Warnings:storage.Warnings(nil)}
got: &promql.Result{Err:error(nil), Value:promql.Vector{}, Warnings:storage.Warnings(nil)}
Diff:
--- Expected
+++ Actual
@@ -1,2 +1,2 @@
-(*promql.Result)({pod="nginx-3"} => 1 @[50000])
+(*promql.Result)()

=== RUN TestInstantQuery/disableOptimizers=false/absent_with_present_metric_and_label#01
=== RUN
TestInstantQuery/disableOptimizers=false/absent_with_present_metric_and_label#01/disableFallback=false
testutil.go:91: engine_test.go:2586: ""
exp: &promql.Result{Err:error(nil), Value:promql.Vector{}, Warnings:storage.Warnings(nil)}
got: &promql.Result{Err:error(nil),
Value:promql.Vector{promql.Sample{Point:promql.Point{T:50000, V:0, H:(*histogram.FloatHistogram)
(nil)}, Metric:labels.Labels{labels.Label{Name:"pod", Value:"nginx-1"}, labels.Label{Name:"series",
Value:"1"}}}}, Warnings:storage.Warnings(nil)}
Diff:
--- Expected
+++ Actual
@@ -1,2 +1,2 @@
-(*promql.Result)()
+(*promql.Result)({pod="nginx-1", series="1"} => 0 @[50000])

@yeya24 I am new to this project. I am exploring it. Thank you.

@siddhikhapare Please use the debugger to see how the engine is implemented and that could help you understand how to fix it.