docs(server): auxiliary database read pools default to 2

src/content/docs/server/configuration.mdx

@@ -24,24 +24,26 @@ Every key below is commented out at its default value; uncomment to change it. A
 
 [database]
 # file = "<config-dir>/database.sqlite" # env: KOMGA_DATABASE_FILE
-# pool-size = 8 # read pool size; default clamp(CPU cores, 8, max-pool-size). env: KOMGA_DATABASE_POOLSIZE
+# pool-size = 8 # read pool size; default min(CPU cores, max-pool-size). env: KOMGA_DATABASE_POOLSIZE
 # max-pool-size = 16 # env: KOMGA_DATABASE_MAXPOOLSIZE
 # journal-mode = "WAL" # WAL/DELETE/TRUNCATE/PERSIST/MEMORY/OFF; env: KOMGA_DATABASE_JOURNALMODE
 # busy-timeout = "30s" # default 30s when unset; env: KOMGA_DATABASE_BUSYTIMEOUT
 # Task execution (library scan / analysis / hashing / conversion / maintenance)
 # uses a dedicated read/write pool over the same database file, so background
 # tasks never contend with HTTP/API connections for pool slots. The task write
 # pool is a second writer on the file; keep a busy timeout (default 30s) so
-# concurrent writes wait instead of failing.
+# concurrent writes wait instead of failing. The task read pool defaults to 2
+# connections — task work is serial per worker (TASK_POOL_SIZE defaults to 1);
+# an explicit pool-size applies to the task pool too.
 # [database.pragmas] # extra SQLite pragmas, TOML only
 # synchronous = "NORMAL"
 # cache_size = "-1820" # page cache per connection, negative = KiB; default: 16 MiB per database split between its connections (512..2048 KiB clamp)
 
 [tasks-db]
-# file = "<config-dir>/tasks.sqlite" # env: KOMGA_TASKSDB_FILE; same keys as [database], env prefix KOMGA_TASKSDB
+# file = "<config-dir>/tasks.sqlite" # env: KOMGA_TASKSDB_FILE; same keys as [database] but the read pool defaults to 2, env prefix KOMGA_TASKSDB
 
 [kmrs-db]
-# file = "<config-dir>/kmrs.sqlite" # kmrs-private state (per-book series metadata contributions, komf integration); env: KOMGA_KMRSDB_FILE; same keys as [database], env prefix KOMGA_KMRSDB
+# file = "<config-dir>/kmrs.sqlite" # kmrs-private state (per-book series metadata contributions, komf integration); env: KOMGA_KMRSDB_FILE; same keys as [database] but the read pool defaults to 2, env prefix KOMGA_KMRSDB
 
 [search]
 # data-directory = "<config-dir>/lucene" # tantivy index; env: KOMGA_LUCENE_DATA_DIRECTORY

src/content/docs/server/enhancements/index.mdx

@@ -30,4 +30,5 @@ Intentional differences from the Java behavior:
 - `GET /actuator/sessions` without `?username=` lists all sessions (Java rejects it).
 - `/api/v1/books/{bookId}/next` and `/previous` break `numberSort` ties by book id; Java's tie-handling is unstable — see [Next/previous navigation](/server/enhancements/next-previous).
 - Memory is bounded regardless of CPU cores: 16 MiB SQLite page-cache budget per database (`cache_size` pragma overrides), and `malloc` arenas capped at 2 on Linux/glibc (`MALLOC_ARENA_MAX` overrides; `1` saves more on tiny boxes but serializes C-side allocation).
+- SQL statements that run 500 ms or longer are logged at WARN with their text (log target `komga_db::slow_query`); lock waits count toward the time, so lock-starved writers show up too. The Java version has no slow-query log.
 - Collection/read list covers: adaptive collage of up to 4 member covers (1 full, 2 side-by-side, 3 = 1 tall + 2 stacked, 4 = 2×2) on a blurred, dimmed blowup of the first cover (neutral gray when no cover is available); Java renders a fixed 2×2 grid on black, cycling members.