From 11516f3cc34ddb5d6809c93d593ffb53c5a421ff Mon Sep 17 00:00:00 2001
From: kshitijk4poor <82637225+kshitijk4poor@users.noreply.github.com>
Date: Tue, 7 Jul 2026 14:33:01 +0530
Subject: [PATCH] perf: partial index so the startup NULL-active repair skips
 the table scan
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Review finding: EXPLAIN QUERY PLAN showed the unconditional repair
UPDATE doing SCAN messages (~75-135ms on 500k rows, every startup) —
the existing idx_messages_session_active can't serve an active-only
predicate. A partial index on (active) WHERE active IS NULL costs
near-zero storage on healthy DBs (no NULL rows) and drops the 0-match
repair to ~0.04ms. Lives in DEFERRED_INDEX_SQL because it references
the reconciler-added column.
---
 hermes_state.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/hermes_state.py b/hermes_state.py
index 6e1300f5de4..3702623aac4 100644
--- a/hermes_state.py
+++ b/hermes_state.py
@@ -802,6 +802,8 @@ CREATE INDEX IF NOT EXISTS idx_compression_locks_expires ON compression_locks(ex
 DEFERRED_INDEX_SQL = """
 CREATE INDEX IF NOT EXISTS idx_messages_session_active
     ON messages(session_id, active, timestamp);
+CREATE INDEX IF NOT EXISTS idx_messages_active_null
+    ON messages(active) WHERE active IS NULL;
 CREATE INDEX IF NOT EXISTS idx_sessions_session_key
     ON sessions(session_key, started_at DESC);
 CREATE INDEX IF NOT EXISTS idx_sessions_gateway_peer