perf: Plumb RowCapacityHint through DBQuery to presize frame fields#240
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adamyeats wants to merge 1 commit into
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perf: Plumb RowCapacityHint through DBQuery to presize frame fields#240adamyeats wants to merge 1 commit into
adamyeats wants to merge 1 commit into
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Important
Blocked on grafana/grafana-plugin-sdk-go#1536.
This PR calls
sqlutil.FrameFromRowsWithCapacity, which is introduced in that SDK PR. Do not merge this until #1536 has landed andsqldshas bumpedgrafana-plugin-sdk-goto a release that contains it.Summary
Adds an optional row-count hint that flows from
DriverSettingsthroughDBQueryinto frame construction, so per-column slices can be presized instead of grown row-by-row during scanning.DriverSettings.RowCapacityHint— new optional field.0preserves existing behavior.DBQuery.WithRowCapacityHint(hint)— chainable setter on the query builder.getFramesroutes a non-zero hint tosqlutil.FrameFromRowsWithCapacity; a zero hint falls through to the existingsqlutil.FrameFromRowspath.SQLDatasourceresolves the hint once at init fromdriverSettings.RowCapacityHintand threads it into everyDBQueryon the query / retry / reconnect paths.Drivers that can estimate a floor (paginated queries,
COUNT-first patterns, statements with a hardLIMIT) can set this to avoid per-column slice growth inFrameFromRows. Drivers that don't set it see no behavior change.