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tsdb: couple of postings optimizations#17439

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bboreham merged 4 commits intoprometheus:mainfrom
bboreham:faster-postings
Nov 14, 2025
Merged

tsdb: couple of postings optimizations#17439
bboreham merged 4 commits intoprometheus:mainfrom
bboreham:faster-postings

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ListPostings Seek: check the next item before binary search

It is fairly common that the next item is the one we want, and cheap to check.

We could also start the binary search one position on, but strangely that slows it down.

Speed up intersectPostings.Next

Check if the next position is already a match, in which case we don't have to call Seek.

Refactor BenchmarkIntersect

Do all memory allocation for fixtures ahead of time, so it doesn't show up in benchmark results.
Extract functions so there is less repetition.

I also reduced the case with 100,000 matchers down to 100.
100,000 matchers is not something that could happen while using Prometheus.

Benchmarks:

goos: darwin
goarch: arm64
pkg: github.com/prometheus/prometheus/tsdb/index
cpu: Apple M2
                          │    before    │               after                │
                          │    sec/op    │   sec/op     vs base               │
Intersect/LongPostings1-8   12.739µ ± 0%   9.800µ ± 5%  -23.07% (p=0.002 n=6)
Intersect/LongPostings2-8    52.03m ± 4%   29.45m ± 7%  -43.39% (p=0.002 n=6)
Intersect/ManyPostings-8     57.41µ ± 9%   35.88µ ± 4%  -37.50% (p=0.002 n=6)
geomean                      336.3µ        218.0µ       -35.19%

(Memory allocations are unchanged)

Does this PR introduce a user-facing change?

[PERF] TSDB: Small optimizations to postings index.

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/prombench main

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prombot commented Oct 31, 2025

⏱️ Welcome to Prometheus Benchmarking Tool. ⏱️

Compared versions: PR-17439 and main

After the successful deployment (check status here), the benchmarking results can be viewed at:

Available Commands:

  • To restart benchmark: /prombench restart main
  • To stop benchmark: /prombench cancel
  • To print help: /prombench help

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bboreham commented Nov 1, 2025

CPU is mostly lower, but sometimes higher. Not sure if this is a useful benchmark.

image

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bboreham commented Nov 1, 2025

/prombench cancel

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prombot commented Nov 1, 2025

Benchmark cancel is in progress.

100,000 matchers is not something that could happen while using Prometheus.

Signed-off-by: Bryan Boreham <bjboreham@gmail.com>
Extract functions which pre-create all the memory for the benchmark itself.

Signed-off-by: Bryan Boreham <bjboreham@gmail.com>
It is fairly common that the next item is the one we want, and cheap
to check.

We could also start the binary search one position on, but strangely
that slows it down.

Signed-off-by: Bryan Boreham <bjboreham@gmail.com>
Check if the next position is already a match, in which case we don't
have to call `Seek`.

Signed-off-by: Bryan Boreham <bjboreham@gmail.com>
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Thanks!

Only one suggestion, otherwise LGTM!

@bboreham bboreham merged commit 1240402 into prometheus:main Nov 14, 2025
28 checks passed
@bboreham bboreham deleted the faster-postings branch November 14, 2025 17:37
renovate bot added a commit to sdwilsh/ansible-playbooks that referenced this pull request Jan 10, 2026
##### [\`v3.9.0\`](https://github.com/prometheus/prometheus/releases/tag/v3.9.0)

#### Note for users of Native Histograms

In version 3.9, Native Histograms is no longer experimental, and the feature flag `native-histogram` has no effect.  You must now turn on
the config setting `scrape_native_histograms` to collect Native Histogram samples from exporters.

#### Changelog

- \[CHANGE] Native Histograms are no longer experimental! Make the `native-histogram` feature flag a no-op. Use `scrape_native_histograms` config option instead. [#17528](prometheus/prometheus#17528)
- \[CHANGE] API: Add maximum limit of 10,000 sets of statistics to TSDB status endpoint. [#17647](prometheus/prometheus#17647)
- \[FEATURE] API: Add /api/v1/features for clients to understand which features are supported. [#17427](prometheus/prometheus#17427)
- \[FEATURE] Promtool: Add `start_timestamp` field for unit tests. [#17636](prometheus/prometheus#17636)
- \[FEATURE] Promtool: Add `--format seriesjson` option to `tsdb dump` to output just series labels in JSON format. [#13409](prometheus/prometheus#13409)
- \[FEATURE] Add `--storage.tsdb.delay-compact-file.path` flag for better interoperability with Thanos. [#17435](prometheus/prometheus#17435)
- \[FEATURE] UI: Add an option on the query drop-down menu to duplicate that query panel. [#17714](prometheus/prometheus#17714)
- \[ENHANCEMENT]: TSDB: add flag `--storage.tsdb.block-reload-interval` to configure TSDB Block Reload Interval. [#16728](prometheus/prometheus#16728)
- \[ENHANCEMENT] UI: Add graph option to start the chart's Y axis at zero. [#17565](prometheus/prometheus#17565)
- \[ENHANCEMENT] Scraping: Classic protobuf format no longer requires the unit in the metric name. [#16834](prometheus/prometheus#16834)
- \[ENHANCEMENT] PromQL, Rules, SD, Scraping: Add native histograms to complement existing summaries. [#17374](prometheus/prometheus#17374)
- \[ENHANCEMENT] Notifications: Add a histogram `prometheus_notifications_latency_histogram_seconds` to complement the existing summary. [#16637](prometheus/prometheus#16637)
- \[ENHANCEMENT] Remote-write: Add custom scope support for AzureAD authentication. [#17483](prometheus/prometheus#17483)
- \[ENHANCEMENT] SD: add a `config` label with job name for most `prometheus_sd_refresh` metrics. [#17138](prometheus/prometheus#17138)
- \[ENHANCEMENT] TSDB: New histogram `prometheus_tsdb_sample_ooo_delta`, the distribution of out-of-order samples in seconds. Collected for all samples, accepted or not. [#17477](prometheus/prometheus#17477)
- \[ENHANCEMENT] Remote-read: Validate histograms received via remote-read. [#17561](prometheus/prometheus#17561)
- \[PERF] TSDB: Small optimizations to postings index. [#17439](prometheus/prometheus#17439)
- \[PERF] Scraping: Speed up relabelling of series. [#17530](prometheus/prometheus#17530)
- \[PERF] PromQL: Small optimisations in binary operators. [#17524](prometheus/prometheus#17524), [#17519](prometheus/prometheus#17519).
- \[BUGFIX] UI: PromQL autocomplete now shows the correct type and HELP text for OpenMetrics counters whose samples end in `_total`. [#17682](prometheus/prometheus#17682)
- \[BUGFIX] UI: Fixed codemirror-promql incorrectly showing label completion suggestions after the closing curly brace of a vector selector. [#17602](prometheus/prometheus#17602)
- \[BUGFIX] UI: Query editor no longer suggests a duration unit if one is already present after a number. [#17605](prometheus/prometheus#17605)
- \[BUGFIX] PromQL: Fix some "vector cannot contain metrics with the same labelset" errors when experimental delayed name removal is enabled. [#17678](prometheus/prometheus#17678)
- \[BUGFIX] PromQL: Fix possible corruption of PromQL text if the query had an empty `ignoring()` and non-empty grouping. [#17643](prometheus/prometheus#17643)
- \[BUGFIX] PromQL: Fix resets/changes to return empty results for anchored selectors when all samples are outside the range. [#17479](prometheus/prometheus#17479)
- \[BUGFIX] PromQL: Check more consistently for many-to-one matching in filter binary operators. [#17668](prometheus/prometheus#17668)
- \[BUGFIX] PromQL: Fix collision in unary negation with non-overlapping series. [#17708](prometheus/prometheus#17708)
- \[BUGFIX] PromQL: Fix collision in label\_join and label\_replace with non-overlapping series. [#17703](prometheus/prometheus#17703)
- \[BUGFIX] PromQL: Fix bug with inconsistent results for queries with OR expression when experimental delayed name removal is enabled. [#17161](prometheus/prometheus#17161)
- \[BUGFIX] PromQL: Ensure that `rate`/`increase`/`delta` of histograms results in a gauge histogram. [#17608](prometheus/prometheus#17608)
- \[BUGFIX] PromQL: Do not panic while iterating over invalid histograms. [#17559](prometheus/prometheus#17559)
- \[BUGFIX] TSDB: Reject chunk files whose encoded chunk length overflows int. [#17533](prometheus/prometheus#17533)
- \[BUGFIX] TSDB: Do not panic during resolution reduction of invalid histograms. [#17561](prometheus/prometheus#17561)
- \[BUGFIX] Remote-write Receive: Avoid duplicate labels when experimental type-and-unit-label feature is enabled. [#17546](prometheus/prometheus#17546)
- \[BUGFIX] OTLP Receiver: Only write metadata to disk when experimental metadata-wal-records feature is enabled. [#17472](prometheus/prometheus#17472)
renovate bot added a commit to sdwilsh/ansible-playbooks that referenced this pull request Jan 10, 2026
##### [\`v3.9.1\`](https://github.com/prometheus/prometheus/releases/tag/v3.9.1)

- \[BUGFIX] Agent: fix crash shortly after startup from invalid type of object. [#17802](prometheus/prometheus#17802)
- \[BUGFIX] Scraping: fix relabel keep/drop not working. [#17807](prometheus/prometheus#17807)

---
##### [\`v3.9.0\`](https://github.com/prometheus/prometheus/releases/tag/v3.9.0)

#### Note for users of Native Histograms

In version 3.9, Native Histograms is no longer experimental, and the feature flag `native-histogram` has no effect.  You must now turn on
the config setting `scrape_native_histograms` to collect Native Histogram samples from exporters.

#### Changelog

- \[CHANGE] Native Histograms are no longer experimental! Make the `native-histogram` feature flag a no-op. Use `scrape_native_histograms` config option instead. [#17528](prometheus/prometheus#17528)
- \[CHANGE] API: Add maximum limit of 10,000 sets of statistics to TSDB status endpoint. [#17647](prometheus/prometheus#17647)
- \[FEATURE] API: Add /api/v1/features for clients to understand which features are supported. [#17427](prometheus/prometheus#17427)
- \[FEATURE] Promtool: Add `start_timestamp` field for unit tests. [#17636](prometheus/prometheus#17636)
- \[FEATURE] Promtool: Add `--format seriesjson` option to `tsdb dump` to output just series labels in JSON format. [#13409](prometheus/prometheus#13409)
- \[FEATURE] Add `--storage.tsdb.delay-compact-file.path` flag for better interoperability with Thanos. [#17435](prometheus/prometheus#17435)
- \[FEATURE] UI: Add an option on the query drop-down menu to duplicate that query panel. [#17714](prometheus/prometheus#17714)
- \[ENHANCEMENT]: TSDB: add flag `--storage.tsdb.block-reload-interval` to configure TSDB Block Reload Interval. [#16728](prometheus/prometheus#16728)
- \[ENHANCEMENT] UI: Add graph option to start the chart's Y axis at zero. [#17565](prometheus/prometheus#17565)
- \[ENHANCEMENT] Scraping: Classic protobuf format no longer requires the unit in the metric name. [#16834](prometheus/prometheus#16834)
- \[ENHANCEMENT] PromQL, Rules, SD, Scraping: Add native histograms to complement existing summaries. [#17374](prometheus/prometheus#17374)
- \[ENHANCEMENT] Notifications: Add a histogram `prometheus_notifications_latency_histogram_seconds` to complement the existing summary. [#16637](prometheus/prometheus#16637)
- \[ENHANCEMENT] Remote-write: Add custom scope support for AzureAD authentication. [#17483](prometheus/prometheus#17483)
- \[ENHANCEMENT] SD: add a `config` label with job name for most `prometheus_sd_refresh` metrics. [#17138](prometheus/prometheus#17138)
- \[ENHANCEMENT] TSDB: New histogram `prometheus_tsdb_sample_ooo_delta`, the distribution of out-of-order samples in seconds. Collected for all samples, accepted or not. [#17477](prometheus/prometheus#17477)
- \[ENHANCEMENT] Remote-read: Validate histograms received via remote-read. [#17561](prometheus/prometheus#17561)
- \[PERF] TSDB: Small optimizations to postings index. [#17439](prometheus/prometheus#17439)
- \[PERF] Scraping: Speed up relabelling of series. [#17530](prometheus/prometheus#17530)
- \[PERF] PromQL: Small optimisations in binary operators. [#17524](prometheus/prometheus#17524), [#17519](prometheus/prometheus#17519).
- \[BUGFIX] UI: PromQL autocomplete now shows the correct type and HELP text for OpenMetrics counters whose samples end in `_total`. [#17682](prometheus/prometheus#17682)
- \[BUGFIX] UI: Fixed codemirror-promql incorrectly showing label completion suggestions after the closing curly brace of a vector selector. [#17602](prometheus/prometheus#17602)
- \[BUGFIX] UI: Query editor no longer suggests a duration unit if one is already present after a number. [#17605](prometheus/prometheus#17605)
- \[BUGFIX] PromQL: Fix some "vector cannot contain metrics with the same labelset" errors when experimental delayed name removal is enabled. [#17678](prometheus/prometheus#17678)
- \[BUGFIX] PromQL: Fix possible corruption of PromQL text if the query had an empty `ignoring()` and non-empty grouping. [#17643](prometheus/prometheus#17643)
- \[BUGFIX] PromQL: Fix resets/changes to return empty results for anchored selectors when all samples are outside the range. [#17479](prometheus/prometheus#17479)
- \[BUGFIX] PromQL: Check more consistently for many-to-one matching in filter binary operators. [#17668](prometheus/prometheus#17668)
- \[BUGFIX] PromQL: Fix collision in unary negation with non-overlapping series. [#17708](prometheus/prometheus#17708)
- \[BUGFIX] PromQL: Fix collision in label\_join and label\_replace with non-overlapping series. [#17703](prometheus/prometheus#17703)
- \[BUGFIX] PromQL: Fix bug with inconsistent results for queries with OR expression when experimental delayed name removal is enabled. [#17161](prometheus/prometheus#17161)
- \[BUGFIX] PromQL: Ensure that `rate`/`increase`/`delta` of histograms results in a gauge histogram. [#17608](prometheus/prometheus#17608)
- \[BUGFIX] PromQL: Do not panic while iterating over invalid histograms. [#17559](prometheus/prometheus#17559)
- \[BUGFIX] TSDB: Reject chunk files whose encoded chunk length overflows int. [#17533](prometheus/prometheus#17533)
- \[BUGFIX] TSDB: Do not panic during resolution reduction of invalid histograms. [#17561](prometheus/prometheus#17561)
- \[BUGFIX] Remote-write Receive: Avoid duplicate labels when experimental type-and-unit-label feature is enabled. [#17546](prometheus/prometheus#17546)
- \[BUGFIX] OTLP Receiver: Only write metadata to disk when experimental metadata-wal-records feature is enabled. [#17472](prometheus/prometheus#17472)
renovate bot added a commit to sdwilsh/ansible-playbooks that referenced this pull request Jan 10, 2026
##### [\`v3.9.1\`](https://github.com/prometheus/prometheus/releases/tag/v3.9.1)

- \[BUGFIX] Agent: fix crash shortly after startup from invalid type of object. [#17802](prometheus/prometheus#17802)
- \[BUGFIX] Scraping: fix relabel keep/drop not working. [#17807](prometheus/prometheus#17807)

---
##### [\`v3.9.0\`](https://github.com/prometheus/prometheus/releases/tag/v3.9.0)

#### Note for users of Native Histograms

In version 3.9, Native Histograms is no longer experimental, and the feature flag `native-histogram` has no effect.  You must now turn on
the config setting `scrape_native_histograms` to collect Native Histogram samples from exporters.

#### Changelog

- \[CHANGE] Native Histograms are no longer experimental! Make the `native-histogram` feature flag a no-op. Use `scrape_native_histograms` config option instead. [#17528](prometheus/prometheus#17528)
- \[CHANGE] API: Add maximum limit of 10,000 sets of statistics to TSDB status endpoint. [#17647](prometheus/prometheus#17647)
- \[FEATURE] API: Add /api/v1/features for clients to understand which features are supported. [#17427](prometheus/prometheus#17427)
- \[FEATURE] Promtool: Add `start_timestamp` field for unit tests. [#17636](prometheus/prometheus#17636)
- \[FEATURE] Promtool: Add `--format seriesjson` option to `tsdb dump` to output just series labels in JSON format. [#13409](prometheus/prometheus#13409)
- \[FEATURE] Add `--storage.tsdb.delay-compact-file.path` flag for better interoperability with Thanos. [#17435](prometheus/prometheus#17435)
- \[FEATURE] UI: Add an option on the query drop-down menu to duplicate that query panel. [#17714](prometheus/prometheus#17714)
- \[ENHANCEMENT]: TSDB: add flag `--storage.tsdb.block-reload-interval` to configure TSDB Block Reload Interval. [#16728](prometheus/prometheus#16728)
- \[ENHANCEMENT] UI: Add graph option to start the chart's Y axis at zero. [#17565](prometheus/prometheus#17565)
- \[ENHANCEMENT] Scraping: Classic protobuf format no longer requires the unit in the metric name. [#16834](prometheus/prometheus#16834)
- \[ENHANCEMENT] PromQL, Rules, SD, Scraping: Add native histograms to complement existing summaries. [#17374](prometheus/prometheus#17374)
- \[ENHANCEMENT] Notifications: Add a histogram `prometheus_notifications_latency_histogram_seconds` to complement the existing summary. [#16637](prometheus/prometheus#16637)
- \[ENHANCEMENT] Remote-write: Add custom scope support for AzureAD authentication. [#17483](prometheus/prometheus#17483)
- \[ENHANCEMENT] SD: add a `config` label with job name for most `prometheus_sd_refresh` metrics. [#17138](prometheus/prometheus#17138)
- \[ENHANCEMENT] TSDB: New histogram `prometheus_tsdb_sample_ooo_delta`, the distribution of out-of-order samples in seconds. Collected for all samples, accepted or not. [#17477](prometheus/prometheus#17477)
- \[ENHANCEMENT] Remote-read: Validate histograms received via remote-read. [#17561](prometheus/prometheus#17561)
- \[PERF] TSDB: Small optimizations to postings index. [#17439](prometheus/prometheus#17439)
- \[PERF] Scraping: Speed up relabelling of series. [#17530](prometheus/prometheus#17530)
- \[PERF] PromQL: Small optimisations in binary operators. [#17524](prometheus/prometheus#17524), [#17519](prometheus/prometheus#17519).
- \[BUGFIX] UI: PromQL autocomplete now shows the correct type and HELP text for OpenMetrics counters whose samples end in `_total`. [#17682](prometheus/prometheus#17682)
- \[BUGFIX] UI: Fixed codemirror-promql incorrectly showing label completion suggestions after the closing curly brace of a vector selector. [#17602](prometheus/prometheus#17602)
- \[BUGFIX] UI: Query editor no longer suggests a duration unit if one is already present after a number. [#17605](prometheus/prometheus#17605)
- \[BUGFIX] PromQL: Fix some "vector cannot contain metrics with the same labelset" errors when experimental delayed name removal is enabled. [#17678](prometheus/prometheus#17678)
- \[BUGFIX] PromQL: Fix possible corruption of PromQL text if the query had an empty `ignoring()` and non-empty grouping. [#17643](prometheus/prometheus#17643)
- \[BUGFIX] PromQL: Fix resets/changes to return empty results for anchored selectors when all samples are outside the range. [#17479](prometheus/prometheus#17479)
- \[BUGFIX] PromQL: Check more consistently for many-to-one matching in filter binary operators. [#17668](prometheus/prometheus#17668)
- \[BUGFIX] PromQL: Fix collision in unary negation with non-overlapping series. [#17708](prometheus/prometheus#17708)
- \[BUGFIX] PromQL: Fix collision in label\_join and label\_replace with non-overlapping series. [#17703](prometheus/prometheus#17703)
- \[BUGFIX] PromQL: Fix bug with inconsistent results for queries with OR expression when experimental delayed name removal is enabled. [#17161](prometheus/prometheus#17161)
- \[BUGFIX] PromQL: Ensure that `rate`/`increase`/`delta` of histograms results in a gauge histogram. [#17608](prometheus/prometheus#17608)
- \[BUGFIX] PromQL: Do not panic while iterating over invalid histograms. [#17559](prometheus/prometheus#17559)
- \[BUGFIX] TSDB: Reject chunk files whose encoded chunk length overflows int. [#17533](prometheus/prometheus#17533)
- \[BUGFIX] TSDB: Do not panic during resolution reduction of invalid histograms. [#17561](prometheus/prometheus#17561)
- \[BUGFIX] Remote-write Receive: Avoid duplicate labels when experimental type-and-unit-label feature is enabled. [#17546](prometheus/prometheus#17546)
- \[BUGFIX] OTLP Receiver: Only write metadata to disk when experimental metadata-wal-records feature is enabled. [#17472](prometheus/prometheus#17472)
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