Database: ZEO¶

ZEO is a mature client-server storage created for ZODB for sharing a single storage among many clients. All options can be found in the Zope Configuration Reference under <zeoclient>.

Main settings¶

Setting	Default
`db_zeo_server`	`localhost:8100`
`db_zeo_name`	`1`
`db_zeo_storage`	(unset, default `1`)

Caching¶

db_cache_size and db_cache_size_bytes from Database: common settings are taken into account. Additional persistent caching is possible.

Setting	Default
`db_zeo_client`	(unset)
`db_zeo_var`	(unset, system temp)
`db_zeo_cache_size`	`128MB`

db_zeo_client – Enables persistent cache files. Set the persistent cache name that is used to construct the cache filenames. This enables the ZEO cache to persist across application restarts. Persistent cache files are disabled by default. If disabled, the client creates a temporary cache that will only be used by the current object. The string passed here is used to construct the cache filenames.

db_zeo_var – The directory where persistent cache files are stored. By default cache files, if they are persistent, are stored in the current directory.

db_zeo_cache_size – Set the size of the file based ZEO client cache. The ZEO cache is a disk based cache shared between application threads. It is stored either in temporary files or, in case you activate persistent cache files with the db_zeo_client option, in the folder designated by db_zeo_var.

Authentication¶

ZEO supports authentication. You need to activate ZEO authentication on the server side as well for this to work. Without this anyone that can connect to the database server’s socket can read and write arbitrary data.

Setting	Default
`db_zeo_username`	(unset, no auth)
`db_zeo_password`	(unset)
`db_zeo_realm`	`ZEO`

db_zeo_username – Enable ZEO authentication and use the given username when accessing the ZEO server. It is obligatory to also specify a db_zeo_password.

Advanced options¶

Setting	Default	Allowed Values
`db_zeo_read_only_fallback`	`false`	`true`, `false`
`db_zeo_read_only`	`false`	`true`, `false`
`db_zeo_drop_cache_rather_verify`	`false`	`true`, `false`
`db_zeo_client_label`	(unset)	string
`db_zeo_wait`	(unset, default `true`)	`true`, `false`

db_zeo_read_only_fallback – A flag indicating whether a read-only remote storage should be acceptable as a fallback when no writable storages are available.

db_zeo_drop_cache_rather_verify – Indicates that the cache should be dropped rather than verified when the verification optimization is not available (e.g. when the ZEO server restarted).

db_zeo_storage – The name of the server-side storage to use. Default is 1. Only needed when the ZEO server exports multiple named storages.

db_zeo_client_label – A label for this ZEO client that is sent to the server for logging and monitoring purposes. Useful in multi-instance deployments to identify which client is connected.

db_zeo_wait – Whether to wait for a ZEO server connection at startup. Default is true. Set to false for testing or CI scenarios where the server may not be available.