GetFingerprintsForLabelSet() does OR, not AND on labels

[juliusv]

The expression:

targets_healthy_scrape_latency_ms{percentile="0.010000"}

Yields 12 vector elements where it should only yield one:

request_metrics_latency_equal_tallying_microseconds{instance='http://localhost:9090/metrics.json',percentile='0.010000'} => 657 @[2013-01-13 05:25:59.236345 +0100 CET]
requests_metrics_latency_equal_accumulating_microseconds{instance='http://localhost:9090/metrics.json',percentile='0.010000'} => 657 @[2013-01-13 05:25:59.236345 +0100 CET]
requests_metrics_latency_logarithmic_accumulating_microseconds{instance='http://localhost:9090/metrics.json',percentile='0.010000'} => 657 @[2013-01-13 05:25:59.236345 +0100 CET]
requests_metrics_latency_logarithmic_tallying_microseconds{instance='http://localhost:9090/metrics.json',percentile='0.010000'} => 657 @[2013-01-13 05:25:59.236345 +0100 CET]
sample_append_disk_latency_microseconds{instance='http://localhost:9090/metrics.json',percentile='0.010000'} => 725 @[2013-01-13 05:25:59.236345 +0100 CET]
targets_healthy_scrape_latency_ms{instance='http://localhost:9090/metrics.json',percentile='0.010000'} => 1.751 @[2013-01-13 05:25:59.236345 +0100 CET]
targets_healthy_scrape_latency_ms{instance='http://localhost:9090/metrics.json',percentile='0.010000'} => 1.751 @[2013-01-13 05:25:59.236345 +0100 CET]
targets_healthy_scrape_latency_ms{instance='http://localhost:9090/metrics.json',percentile='0.050000'} => 1.751 @[2013-01-13 05:25:59.236345 +0100 CET]
targets_healthy_scrape_latency_ms{instance='http://localhost:9090/metrics.json',percentile='0.500000'} => 1.751 @[2013-01-13 05:25:59.236345 +0100 CET]
targets_healthy_scrape_latency_ms{instance='http://localhost:9090/metrics.json',percentile='0.900000'} => 1.751 @[2013-01-13 05:25:59.236345 +0100 CET]
targets_healthy_scrape_latency_ms{instance='http://localhost:9090/metrics.json',percentile='0.990000'} => 1.751 @[2013-01-13 05:25:59.236345 +0100 CET]
targets_unhealthy_scrape_latency_ms{instance='http://localhost:9090/metrics.json',percentile='0.010000'} => NaN @[2013-01-13 05:25:59.236345 +0100 CET]

This is an OR of the labels, not an AND (all timeseries that match either the name of the metric OR the percentile value). The bug is in GetFingerprintsForLabelSet():

fmt.Printf("===========> %v\n", labels);
fingerprints, err := p.persistence.GetFingerprintsForLabelSet(&labels)
fmt.Printf("===========> %v\n", fingerprints);

This outputs this:

===========> map[percentile:0.010000 name:targets_healthy_scrape_latency_ms]
===========> [0xf8402fd650 0xf8402fd660 0xf8402fd680 0xf8402fd690 0xf8402fd6a0 0xf8402fd750 0xf8402fd760 0xf8402fd770 0xf8402fd780 0xf8402fd790 0xf8402fd7a0 0xf8402fd7b0]

Note the 12 fingerprints where there should only be one!

The reason is that GetFingerprintsForLabelSet() steps through all labels and fetches the matching metrics for each label, thus resulting in an OR.

[matttproud]

Try patching in https://github.com/matttproud/prometheus/pull/30 and letting me know if this does what you expect. I am not happy with how messy this is, but I want to unblock you.

[lock]

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