Remove WAITFOR DECOMPRESS filters from query stats and query store#853
Merged
erikdarlingdata merged 2 commits intodevfrom Apr 16, 2026
Merged
Remove WAITFOR DECOMPRESS filters from query stats and query store#853erikdarlingdata merged 2 commits intodevfrom
erikdarlingdata merged 2 commits intodevfrom
Conversation
The CAST(DECOMPRESS(...)) NOT LIKE N'WAITFOR%' filter was decompressing query text on every row in query_stats and query_store_data just to skip WAITFOR queries. WAITFOR has no plan and no meaningful stats — it only matters in query snapshots (active sessions), where the filter remains. On a 742K-row query_stats table, this was a significant contributor to the 120-second query timeouts reported in #835. The snapshot filters (report.query_snapshots) and MCP phased queries are untouched — they filter after TOP on already-hydrated text. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
All three grid queries now use a 3-phase pattern: 1. Aggregate numerics into temp table (no DECOMPRESS) 2. Sum across lifetimes, rank TOP 500 3. OUTER APPLY to decompress text/plan for only the 500 winners On a 742K-row query_stats table, this reduces DECOMPRESS calls from 742K to 500 — eliminating the 16+ minute query times reported in #835. Matches the existing phased pattern used by the MCP query tools. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Summary
CAST(DECOMPRESS(...)) NOT LIKE N'WAITFOR%'from 3 queries:GetQueryStatsAsync— query_stats grid (the 120-second timeout culprit)GetQueryStoreDataAsync— query store griddm_exec_query_stats/ Query Store data is pointlessNot changed (these are legitimate):
report.query_snapshots) — WAITFOR shows up in active sessionsRelated to #835
Test plan
🤖 Generated with Claude Code