Fix Memory Grants always 0 in Memory Utilization chart (#978)#984
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GetMemoryDataAsync correlated collect.memory_grant_stats to collect.memory_stats with an exact collection_time equality. Those two tables are populated by separate collectors, each stamping its own SYSDATETIME() default, so the timestamps never line up — the correlated subquery matched 0 rows and ISNULL collapsed it to 0 on every sample. Replace the exact-match subquery with a nearest-snapshot lookup: the TOP (1) grant snapshot within +/-5 minutes, ordered by absolute time distance. Applied to both query branches (fromDate/toDate and hoursBack). Dashboard-only change; fixes historical data too. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Summary
Fixes #978 — the "Memory Grants" line on Overview → Resource Overview → Memory Utilization is always 0 MB.
GetMemoryDataAsynccorrelatedcollect.memory_grant_statstocollect.memory_statswith an exactcollection_timeequality. The two tables are filled by separate collectors, each stamping its ownSYSDATETIME()default, so the timestamps never align — the correlated subquery matched 0 rows andISNULL(...,0)collapsed it to 0 on every sample.Verified on sql2022's
PerformanceMonitorDB: 0 rows wherememory_stats.collection_timeequals anymemory_grant_stats.collection_time.Fix
Replaced the exact-match subquery with a nearest-snapshot lookup — the
TOP (1)grant snapshot within ±5 minutes, ordered by absolute time distance. Applied to both query branches (fromDate/toDateandhoursBack).Dashboard-only embedded-SQL change; no schema or install-script changes. Fixes historical data too.
Test plan
dotnet build Dashboard/Dashboard.csproj -c Debug— succeeds, 0 warnings/errors🤖 Generated with Claude Code