From 53374c26afb346ec78ffe3a3cefb74492701e5c5 Mon Sep 17 00:00:00 2001
From: Phillipxh <150742483+Phillipxh@users.noreply.github.com>
Date: Fri, 30 Oct 2026 22:35:51 +0100
Subject: [PATCH] fix(database): drop the join-without-index rules

Select_full_join and Join_without_index_rate cannot be acted on by an
admin:

- The queries behind the counters are not logged by default, so there is
  no way to tell which query did the join.
- Most of them are Nextcloud's own: the core setup checks introspect the
  schema through information_schema, whose tables have no indexes, so
  every visit of Administration -> Overview adds to Select_full_join.
- Even if the query were known, adding an index by hand would make the
  schema check report it as unexpected.

Remove both rules, as suggested in review.

Fixes #1245

Assisted-by: ClaudeCode:claude-opus-5-5
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019TNUHUT6jaQ3BHvjvdf4Ny
Signed-off-by: Phillipxh <150742483+Phillipxh@users.noreply.github.com>
---
 lib/Database/Advisor.php           |  2 --
 lib/Database/RuleSet/Mysql.php     | 29 -----------------------------
 tests/lib/Database/AdvisorTest.php | 16 ----------------
 3 files changed, 47 deletions(-)

diff --git a/lib/Database/Advisor.php b/lib/Database/Advisor.php
index f905a9d5..f33f655c 100644
--- a/lib/Database/Advisor.php
+++ b/lib/Database/Advisor.php
@@ -49,7 +49,6 @@ class Advisor {
 		'Aborted_connects',
 		'Thread_cache_hit_rate',
 		'Slow_query_ratio',
-		'Select_full_join',
 		'Sort_merge_passes',
 		'Created_tmp_disk_tables',
 		'Innodb_buffer_pool_hit_rate',
@@ -61,7 +60,6 @@ class Advisor {
 		'Slow_query_rate',
 		'Sort_rows',
 		'Sort_merge_passes_rate',
-		'Join_without_index_rate',
 		'Handler_read_first_rate',
 		'Handler_read_rnd_rate',
 		'Handler_read_rnd_next_rate',
diff --git a/lib/Database/RuleSet/Mysql.php b/lib/Database/RuleSet/Mysql.php
index 77e3bcfb..6848f755 100644
--- a/lib/Database/RuleSet/Mysql.php
+++ b/lib/Database/RuleSet/Mysql.php
@@ -177,20 +177,6 @@ private function build(): array {
 			requires: ['Slow_queries', 'Questions'],
 		);
 
-		$rules[] = new Rule(
-			id: 'Select_full_join',
-			name: 'Joins without indexes',
-			category: 'Performance',
-			severity: Rule::SEVERITY_WARNING,
-			formula: 'Select_full_join / Questions * 100',
-			test: 'value > 0.05',
-			issue: 'Some joins are scanning entire tables because no usable index exists on the join column.',
-			recommendation: 'Identify the offending queries (set log_queries_not_using_indexes) and add the missing indexes.',
-			justification: '%s%% of queries did a full join without an index.',
-			justificationFormula: 'value',
-			requires: ['Select_full_join', 'Questions'],
-		);
-
 		$rules[] = new Rule(
 			id: 'Sort_merge_passes',
 			name: 'Sort buffer passes',
@@ -488,21 +474,6 @@ private function build(): array {
 		);
 
 		// Performance / joins + scans (rate-based companions to existing absolute checks)
-		$rules[] = new Rule(
-			// upstream id: "Rate of joins without indexes"
-			id: 'Join_without_index_rate',
-			name: 'Join-without-index rate',
-			category: 'Performance',
-			severity: Rule::SEVERITY_NOTICE,
-			formula: '(Select_range_check + Select_scan + Select_full_join) / Uptime',
-			test: 'value * 60 * 60 > 1',
-			issue: 'Many SELECTs are doing full table scans or joins without indexes.',
-			recommendation: 'Add indexes for the columns used in JOIN conditions and WHERE filters.',
-			justification: 'Index-less join+scan rate: %s per hour; aim for less than 1.',
-			justificationFormula: 'round(value * 3600, 2)',
-			requires: ['Select_range_check', 'Select_scan', 'Select_full_join', 'Uptime'],
-		);
-
 		$rules[] = new Rule(
 			// upstream id: "Rate of reading first index entry"
 			id: 'Handler_read_first_rate',
diff --git a/tests/lib/Database/AdvisorTest.php b/tests/lib/Database/AdvisorTest.php
index d48c51b2..300e3a89 100644
--- a/tests/lib/Database/AdvisorTest.php
+++ b/tests/lib/Database/AdvisorTest.php
@@ -11,7 +11,6 @@
 
 use OCA\ServerInfo\Database\Advisor;
 use OCA\ServerInfo\Database\ExpressionEvaluator;
-use OCA\ServerInfo\Database\Rule;
 use OCA\ServerInfo\Database\RuleResult;
 use OCA\ServerInfo\Database\RuleSet\Mysql;
 use OCA\ServerInfo\Database\Snapshot;
@@ -135,19 +134,4 @@ public function testReplicaLagPassesOnRunningReplica(): void {
 
 		$this->assertSame(RuleResult::STATUS_OK, $result->status);
 	}
-
-	/**
-	 * Select_scan alone exceeds one per hour on any active Nextcloud, so the
-	 * rule is a hint rather than a warning.
-	 */
-	public function testJoinWithoutIndexRateIsANotice(): void {
-		$result = $this->resultFor('Join_without_index_rate', [
-			'Select_range_check' => 0,
-			'Select_scan' => 50000,
-			'Select_full_join' => 0,
-		]);
-
-		$this->assertSame(RuleResult::STATUS_FAIL, $result->status);
-		$this->assertSame(Rule::SEVERITY_NOTICE, $result->rule->severity);
-	}
 }