Repository navigation
Query Store: skip readable-secondary replicas (readonly_reason bit 8) — RDS/geo replicas were collecting the primary's replicated QS - #1558
Merged
Conversation
Field evidence: 24 RDS read replicas all collecting query_store, each showing actual_state=READ_ONLY, desired=READ_WRITE, readonly_reason=8 (read-only BECAUSE readable secondary). A secondary's persisted QS tables are the PRIMARY's content via replication - collecting there is duplicate, lagged primary data x24, and exactly the pathological volume shape that fed #1557. Why both guards missed: the enumeration's HADR join only catches Always On AG secondaries (RDS replicas pass the "not in any AG" arm), and the #1546 actual_state IN (1,2,4) gate deliberately admits READ_ONLY without asking WHY. Fix: readonly_reason & 8 = 0 (bitmask) at all three eligibility sites - shared collector on-prem + Azure enumerations (Lite+Darling) and the deprecated Dashboard's install/09 proc. The engine's own mechanism-agnostic replica flag covers AG, RDS, and geo-secondaries uniformly. Still collected: operator-set read-only QS on a primary (reason<>8) and 2022+/2025 READ_CAPTURE_SECONDARY (state 4, real local secondary workload). Pins updated: both enumeration-text tests assert the new clause. Lite.Tests 1369/0, Darling.Tests 2161/0 (Release, full). Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
The rationale comment sat INSIDE the N'...' eligibility string and contained an apostrophe, terminating the literal - all four SQL-version-matrix checks failed on the proc definition. The clause stays; the comment now lives in the static proc body where apostrophes are legal, with a note saying exactly why. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
8 of 12 tasks
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Summary
Field evidence from the 24-server RDS fleet: every read replica was collecting query_store, each database showing
actual_state = READ_ONLY,desired_state = READ_WRITE,readonly_reason = 8— the engine's documented "read-only because this database is a readable secondary replica." A secondary's persisted Query Store tables are the primary's content arriving via replication — collecting there yields duplicate, lagged primary data (×24 copies of the same QS), and is exactly the pathological-volume shape that fed the #1557 memory incident.Why both existing guards missed
sys.dm_hadr_database_replica_states— Always On AG only. An RDS read replica is not an AG member, so it passes the "not in any AG" arm looking like a standalone primary.actual_state IN (1, 2, 4)deliberately admits READ_ONLY (correct for an operator-set read-only QS on a primary) but never consults why it is read-only.Fix
AND readonly_reason & 8 = 0(bitmask form) at all three per-database eligibility sites: the shared collector's on-prem and Azure enumeration queries (serving Lite + Darling) and the deprecated Dashboard'sinstall/09proc (bug-fix mirror). Bit 8 is the engine's mechanism-agnostic replica flag — AG secondaries, RDS read replicas, and geo-secondaries are skipped uniformly, with no dependence on which replication technology produced the secondary.Deliberately still collected: operator-set read-only QS on a primary (
readonly_reason <> 8), andREAD_CAPTURE_SECONDARY(state 4 — a 2022+/2025 secondary capturing its own genuinely-local workload).Testing
install/09change rides the standard SQL-version-matrix PR checks (2017/2019/2022/2025).🤖 Generated with Claude Code