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Optimizing "grafana generated" regex matchers#12375

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jesusvazquez merged 1 commit intoprometheus:mainfrom
alanprot:opmize/group-regex
May 30, 2023
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Optimizing "grafana generated" regex matchers#12375
jesusvazquez merged 1 commit intoprometheus:mainfrom
alanprot:opmize/group-regex

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@alanprot alanprot commented May 17, 2023

When using a multi-value variable on Grafana Dashboards the default behavior is to produce regex in the format (a|b). See https://grafana.com/docs/grafana/latest/dashboards/variables/variable-syntax/#regex

This PR is expanding the optimization Prometheus already have on regexes like a|b to regexes like (a|b) and improve the query time and cpu utilization for dashboards with high cardinality variables substantially.

PS: Nothing will change for other types of queries even if they starts and ends with (), like (a|b)|(c|d)

goos: linux
goarch: amd64
pkg: github.com/prometheus/prometheus/tsdb
cpu: Intel(R) Xeon(R) Platinum 8259CL CPU @ 2.50GHz
                                                             │     /tmp/old     │              /tmp/new               │
                                                             │      sec/op      │    sec/op     vs base               │
Querier/Head/PostingsForMatchers/i=~"(1|2|3|4|5|6|20|55)"-32   18796.184µ ± ∞ ¹   2.416µ ± ∞ ¹  -99.99% (p=0.008 n=5)
Querier/Head/PostingsForMatchers/i!~"(1|2|3|4|5|6|20|55)"-32      18.450m ± ∞ ¹   2.238m ± ∞ ¹  -87.87% (p=0.008 n=5)
geomean                                                            18.62m         73.53µ        -99.61%
¹ need >= 6 samples for confidence interval at level 0.95

                                                             │    /tmp/old     │               /tmp/new               │
                                                             │      B/op       │     B/op	vs base               │
Querier/Head/PostingsForMatchers/i=~"(1|2|3|4|5|6|20|55)"-32   1606349.0 ± ∞ ¹     848.0 ± ∞ ¹  -99.95% (p=0.008 n=5)
Querier/Head/PostingsForMatchers/i!~"(1|2|3|4|5|6|20|55)"-32     1.531Mi ± ∞ ¹   1.532Mi ± ∞ ¹   +0.04% (p=0.008 n=5)
geomean                                                          1.532Mi         36.04Ki        -97.70%
¹ need >= 6 samples for confidence interval at level 0.95

                                                             │  /tmp/old   │               /tmp/new               │
                                                             │  allocs/op  │  allocs/op    vs base                │
Querier/Head/PostingsForMatchers/i=~"(1|2|3|4|5|6|20|55)"-32   4.000 ± ∞ ¹   31.000 ± ∞ ¹  +675.00% (p=0.008 n=5)
Querier/Head/PostingsForMatchers/i!~"(1|2|3|4|5|6|20|55)"-32   7.000 ± ∞ ¹   35.000 ± ∞ ¹  +400.00% (p=0.008 n=5)
geomean                                                        5.292          32.94        +522.49%

@alanprot alanprot requested a review from jesusvazquez as a code owner May 17, 2023 18:05
@alanprot alanprot force-pushed the opmize/group-regex branch from d49bbb6 to fdbfa64 Compare May 17, 2023 18:06
yeya24
yeya24 reviewed May 17, 2023
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Opmizing Group Regex
c062711 
Signed-off-by: Alan Protasio <alanprot@gmail.com>
@alanprot alanprot force-pushed the opmize/group-regex branch from 62431fb to c062711 Compare May 19, 2023 22:48
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alanprot commented May 23, 2023

@jesusvazquez 🥺 :D

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jesusvazquez approved these changes May 30, 2023
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I see you are on a mission to improve a lot of the regexes cases 💪

@jesusvazquez jesusvazquez merged commit 73078bf into prometheus:main May 30, 2023
@yeya24 yeya24 mentioned this pull request May 30, 2023
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alanprot commented May 30, 2023

Thanks!! :D

bboreham pushed a commit to bboreham/prometheus that referenced this pull request Jul 24, 2023
@alanprot @bboreham
Opmizing Group Regex (prometheus#12375)
e18ee99 
Signed-off-by: Alan Protasio <alanprot@gmail.com>
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