Postgres perf, path migration, and shutdown race fixes

- Major query performance boost: replaced correlated subqueries with DistinctBy() in BaseItemRepository, added episode deduplication index, and increased default command timeout to 120s.
- Fixed LibraryMonitor shutdown race: added disposal checks and exception handling in FileRefresher to prevent ObjectDisposedException.
- Added PowerShell and SQL utilities for fixing Linux paths in config files and database; new scripts for WebDir and path migration.
- Auto-fix for WebDir in startup.json on load; new helper scripts and docs.
- Added automated weekly DB performance monitoring scripts and reporting.
- Expanded documentation and README for all fixes, scripts, and migration steps.
- Updated SQL scripts for index creation and diagnostics; improved output handling.
- Updated db-config defaults and added new diagnostic/report files.

sql/optimize_peoples_itemvalues_indexes.sql

@@ -0,0 +1,143 @@
+-- ============================================================================
+-- Optimize Indexes for Peoples and ItemValues Tables
+-- Generated: 2026-03-05
+-- Purpose: Reduce sequential scans on high-traffic tables
+-- ============================================================================
+\pset pager off
+
+\echo '========================================='
+\echo 'Optimizing Peoples and ItemValues Indexes'
+\echo '========================================='
+\echo ''
+
+-- ============================================================================
+-- 1. PEOPLES TABLE OPTIMIZATION
+-- ============================================================================
+-- Current Issue: 144,299 sequential scans reading 13.7 BILLION rows
+-- Current Indexes: IX_Peoples_Name, PK_Peoples
+-- Target: Reduce sequential scans by 80%+
+
+\echo '1. Creating Peoples Table Indexes...'
+\echo '-----------------------------------------'
+
+-- Index for queries filtering by Name (case-insensitive searches)
+-- Supports ILIKE/LIKE queries
+CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_peoples_name_lower
+ON library."Peoples" (LOWER("Name"))
+WHERE "Name" IS NOT NULL;
+
+-- Composite index for common join patterns (People -> Items)
+-- Supports queries that need both Id and Name
+CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_peoples_id_name
+ON library."Peoples" ("Id", "Name")
+WHERE "Name" IS NOT NULL;
+
+-- Index for external ID lookups (TMDB, IMDB, etc.)
+-- Supports metadata provider queries
+CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_peoples_providerid
+ON library."Peoples" ("ProviderIds")
+WHERE "ProviderIds" IS NOT NULL;
+
+\echo 'Peoples indexes created successfully!'
+\echo ''
+
+-- ============================================================================
+-- 2. ITEMVALUES TABLE OPTIMIZATION
+-- ============================================================================
+-- Current Issue: 506,048 sequential scans reading 3.7 BILLION rows
+-- Current Indexes: IX_ItemValues_Type_CleanValue, IX_ItemValues_Type_Value
+-- Target: Increase index usage from 82% to 95%+
+
+\echo '2. Creating ItemValues Table Indexes...'
+\echo '-----------------------------------------'
+
+-- Index for CleanValue lookups without Type filter
+-- Supports genre/tag searches that don't filter by type
+CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_itemvalues_cleanvalue
+ON library."ItemValues" ("CleanValue")
+WHERE "CleanValue" IS NOT NULL;
+
+-- Index for Value lookups (with original casing)
+-- Supports exact value matches
+CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_itemvalues_value
+ON library."ItemValues" ("Value")
+WHERE "Value" IS NOT NULL;
+
+-- Composite index for ItemValuesMap joins
+-- Optimizes: ItemValues JOIN ItemValuesMap ON ItemValues.Id = ItemValuesMap.ItemValueId
+CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_itemvalues_id_type_cleanvalue
+ON library."ItemValues" ("Id", "Type", "CleanValue");
+
+-- Index for reverse lookups (find all items with specific values)
+-- Supports queries like "find all genres" or "find all tags"
+CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_itemvalues_type_id
+ON library."ItemValues" ("Type", "Id")
+WHERE "Type" IS NOT NULL;
+
+-- Partial index for common value types (Genre, Tags, Studio, etc.)
+-- Reduces index size while covering most common queries
+CREATE INDEX CONCURRENTLY IF NOT EXISTS idx_itemvalues_common_types
+ON library."ItemValues" ("Type", "CleanValue", "Id")
+WHERE "Type" IN (0, 1, 2, 3, 4, 5, 6, 7, 8); -- Common metadata types
+
+\echo 'ItemValues indexes created successfully!'
+\echo ''
+
+-- ============================================================================
+-- 3. UPDATE STATISTICS
+-- ============================================================================
+
+\echo '3. Updating Table Statistics...'
+\echo '-----------------------------------------'
+
+-- Update statistics so query planner knows about new indexes
+ANALYZE VERBOSE library."Peoples";
+ANALYZE VERBOSE library."ItemValues";
+
+\echo ''
+\echo '========================================='
+\echo 'Optimization Complete!'
+\echo '========================================='
+\echo ''
+
+-- ============================================================================
+-- 4. VERIFY NEW INDEXES
+-- ============================================================================
+
+\echo '4. Verifying New Indexes...'
+\echo '-----------------------------------------'
+
+-- Show all indexes on Peoples table
+\echo ''
+\echo 'Peoples Table Indexes:'
+SELECT
+    schemaname,
+    tablename,
+    indexname,
+    pg_size_pretty(pg_relation_size(indexrelid)) AS index_size
+FROM pg_stat_user_indexes
+WHERE schemaname = 'library'
+  AND tablename = 'Peoples'
+ORDER BY indexname;
+
+\echo ''
+\echo 'ItemValues Table Indexes:'
+-- Show all indexes on ItemValues table
+SELECT
+    schemaname,
+    tablename,
+    indexname,
+    pg_size_pretty(pg_relation_size(indexrelid)) AS index_size
+FROM pg_stat_user_indexes
+WHERE schemaname = 'library'
+  AND tablename = 'ItemValues'
+ORDER BY indexname;
+
+\echo ''
+\echo '========================================='
+\echo 'Next Steps:'
+\echo '1. Use Jellyfin normally for a few hours'
+\echo '2. Run: sql\diagnostics.sql'
+\echo '3. Check if sequential scans decreased'
+\echo '4. Run: sql\query-analysis.sql for slow query details'
+\echo '========================================='