Database Tuning

Server Settings → Database → Tuning. The curated MariaDB / PostgreSQL configuration tuner. M46, ADR-0098.

What can be tuned

Only whitelisted keys may be edited from the panel. The whitelist exists because uncurated [mysqld] settings can break replication, crash recovery, or memory accounting in ways that are very hard to revert from the UI.

MariaDB keys (representative)

Key	Default	Notes
innodb_buffer_pool_size	25% of RAM	The single biggest dial. Larger is better up to ≈70% of RAM.
innodb_log_file_size	96 MiB	Larger reduces checkpoint pressure on write-heavy workloads.
max_connections	200	Raise only when you observe Too many connections errors.
query_cache_size	0	MariaDB 10.3+ deprecates the query cache; the panel keeps it off.
thread_cache_size	16	Raise on bursty connection patterns.
tmp_table_size / max_heap_table_size	32 MiB each	Increase if Created_tmp_disk_tables is high.

PostgreSQL keys (representative)

Key	Default	Notes
shared_buffers	25% of RAM	Equivalent to InnoDB buffer pool.
effective_cache_size	50% of RAM	Planner hint.
work_mem	16 MiB	Per-sort, per-hash. Beware multiplication by concurrent connections.
maintenance_work_mem	256 MiB	Used during VACUUM, CREATE INDEX.
max_connections	100	Raise sparingly; pair with a pooler at high counts.

Apply flow

1. The admin edits the values.
2. Click Apply. Each change writes to the db_tuning table.
3. The reconciler (db_tuning_reconcile.go) renders the override file (/etc/mysql/mariadb.conf.d/jabali-tuning.cnf for MariaDB, postgresql.auto.conf for PostgreSQL).
4. The agent issues db.config.apply, which sets dynamic variables in-place when possible (no restart) and restarts the daemon when the key requires it.

The action is audited and announced via Notifications.

Why “curated”

A free-text [mysqld] block exposed to operators historically produced two failure modes:

1. Typos that silently dropped settings (innodb_buffer_pool_siz = ...).
2. Settings that interacted in non-obvious ways with innodb_log_file_size or page-size assumptions and broke crash recovery.

The whitelist enforces correctness at submit time and rejects out-of-range values before they reach the daemon.

Custom tuning beyond the whitelist

Edits to /etc/mysql/mariadb.conf.d/zz-custom.cnf (operator-owned) are preserved across jabali update. The reconciler does not touch this file. Use this path for [client] section changes, alternate storage engine configs, etc., that the curated tuner does not cover.

CLI

jabali admin db config apply

Re-applies the persisted tuning state. Useful after a daemon restart that lost dynamic variables not yet written to the override file.