[SR-Users] [Presence] publ_cache=2 usage

[Denys Pozniak]

Hello!

Could somebody explain how the parameters *publ_cache=2* and
*subs_db_mode* depend
on each other?
Do I understand correctly that only the following modes of *subs_db_mode* are
allowed 0,1,2?






*subs_db_mode:0 - This disables database completely. Only memory will be
used. Subscriptions will not survive restart. Use this value if you need a
really fast presence module and subscription persistence is not necessary
or is provided by other means.1 - Write-Through scheme. Subscriptions are
updated synchronously in database and in memory(used for read operations).
Use this scheme if speed is not top priority, but it's important that no
subscriptions will be lost during crash or reboot or if you have an
external application that reads the state of the subscriptions from
database and they need to be updated synchronously.2 - Write-Back scheme.
This is a combination of previous two schemes. All changes are made to
memory and database synchronization is done in the timer. The timer deletes
all expired contacts and flushes all modified or new subscriptions to
database. Use this scheme if you encounter high-load peaks and want them to
process as fast as possible. Latency of this mode is much lower than
latency of mode 1, but slightly higher than latency of mode 0. To control
the interval at which data is flushed to database, set the db_update_period
parameter.3 - DB-Only scheme. No memory cache is kept, all operations being
directly performed with the database. The timer deletes all expired
subscriptions from database. The mode is useful if you configure more
servers sharing the same DB without any replication at SIP level. The mode
may be slower due the high number of DB operation.*
-- 

BR,
Denys Pozniak
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