Database: common settings

Core database settings shared across all storage backends. See Understanding storage backends for a comparison.

Setting	Default	Allowed Values
db_storage	direct	direct, relstorage, zeo, pgjsonb
db_cache_size	30000	integer
db_cache_size_bytes	(unset)	byte-size (KB, MB, GB)
db_large_record_size	(unset, default 16MB)	byte-size (KB, MB, GB)
db_pool_size	(unset, default 7)	integer
db_pool_timeout	(unset)	integer (seconds)
max_conflict_retries	3	integer

db_cache_size – ZODB cache target maximum number of non-ghost objects per connection. One cache is created for each active parallel running thread. A powerful tuning knob – if in doubt, do not touch.

db_cache_size_bytes – Additional memory limit on top of db_cache_size. The cache is kept below whichever limit is hit first. Set to 0 to disable the byte-size check.

db_large_record_size – When object records exceed this size a warning is issued suggesting blobs should be used instead.

db_pool_size – Expected maximum number of simultaneously open connections. No hard limit; exceeding it logs a warning, exceeding 2x logs a critical message.

db_pool_timeout – The maximum time in seconds that an unused connection should be kept open. When set, idle connections older than this value are closed automatically. Useful for managing memory in deployments with many worker threads.