Align default BanyanDB stage segmentInterval to integer multiples

[mrproliu]

Improve the efficiency of BanyanDB hot → warm → cold lifecycle stage migration (default config)

Each coarser lifecycle stage's segmentInterval should be an integer multiple of the immediately finer (preceding) stage's. BanyanDB segments are epoch-anchored, so when the coarser interval is a multiple of the finer one, every source segment nests entirely inside exactly one target segment and the tier migration stays on the cheap whole-segment fast path (byte-copy). A non-multiple interval makes source segments straddle target boundaries, forcing a row-by-row decode-and-re-bucket slow path that costs significantly more CPU, IO, and peak memory, and produces more small parts for the background merge loop to compact. It does not affect correctness — only migration efficiency.

This aligns the shipped defaults that previously violated the rule:

Group	Field	Old → New
records	cold segmentInterval	3 → 4 (multiple of warm=2)
metricsMinute	cold segmentInterval	5 → 6 (multiple of warm=3)
metricsHour	warm segmentInterval	7 → 10 (multiple of hot=5)
metricsHour	cold segmentInterval	15 → 20 (multiple of warm=10)

All adjusted values still satisfy hot ≤ warm ≤ cold and segmentInterval ≤ that stage's ttl. The other groups already comply and are unchanged.

• The improvement is structural (whole-segment byte-copy vs row-by-row re-bucketing), not a micro-optimization, so no micro-benchmark applies; the fast/slow path mechanism is documented in the stages guide.

• Theory proof: see the new "integer multiple" guideline in docs/en/banyandb/stages.md, and the BanyanDB migration fast/slow path behavior.

• If this pull request closes/resolves/fixes an existing issue, replace the issue number. Closes #.

• Update the CHANGES log.

[Copilot]

Pull request overview

This pull request updates SkyWalking’s shipped BanyanDB default lifecycle stage segmentInterval values so that each coarser stage uses an integer-multiple interval of the preceding stage, improving hot → warm → cold migration efficiency by keeping migrations on the whole-segment fast path.

Changes:

• Adjust default segmentInterval values in BanyanDB bydb.yml (runtime + test resource) for records, metricsMinute, and metricsHour to be integer multiples across stages.
• Update the configuration vocabulary documentation to reflect the new defaults.
• Document the “integer multiple” guideline in the BanyanDB stages guide and record the change in the changelog.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
oap-server/server-storage-plugin/storage-banyandb-plugin/src/test/resources/bydb.yml	Updates test fixture defaults for stage segmentInterval values to match the new integer-multiple alignment.
oap-server/server-starter/src/main/resources/bydb.yml	Updates shipped default BanyanDB stage segmentInterval values for more efficient lifecycle migrations.
docs/en/setup/backend/configuration-vocabulary.md	Updates documented default values for the affected segmentInterval settings.
docs/en/changes/changes.md	Adds a changelog entry describing the default segmentInterval alignment improvement.
docs/en/banyandb/stages.md	Updates the stages guide example default and adds an “integer multiple” guideline to explain migration efficiency implications.

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[mrproliu]

Update the stages.md from metricsMin to metricsMinute.