Sylvain Lebresne created CASSANDRA-12222:
--------------------------------------------
Summary: Per-node overrides for table settings
Key: CASSANDRA-12222
URL: https://issues.apache.org/jira/browse/CASSANDRA-12222
Project: Cassandra
Issue Type: Improvement
Components: CQL
Reporter: Sylvain Lebresne
Priority: Minor
There is a few cases where it's convenient to set some table parameters on only
one of a few nodes. For instance, it's useful for experimenting with settings
like caching options, compaction, compression, read repair chance, gcGrace ...
Another case is when you want to completely migrate to a new setting, but want
to do that node-per-node (mainly useful when switching compaction strategy, see
CASSANDRA-10898).
I'll note that we can already do some of this through JMX for some of the
settings as we have methods like
{{ColumnFamilyStoreMBean.setCompactionParameters()}}, but:
# parameters settings are initially set in CQL. Having to go to JMX for this
sounds less consistent to me. The fact we have both a
{{ColumnFamilyStoreMBean.setCompactionParameters()}} and a
{{ColumnFamilyStoreMBean.setCompactionParametersJson()}} (as I assume the
former one is inconvenient to use) is also proof to me than JMX ain't terribly
appropriate.
# I think this can be potentially useful for almost all table settings, but we
don't expose JMX methods for all settings, and it would be annoying to have to.
The method suggested below wouldn't have to be updated every time we add a new
settings (if done right).
# Changing options through JMX is not persistent across restarts. This may
arguably be fine in some cases, but if you're trying to migrate your compaction
strategy node per node, or want to experiment with a setting over a mediumish
time period, it's mostly a pain.
So what I suggest would be add node overrides in the normal table setting
(which would be part of the schema as any other setting). In other words, if
you want to set LCS for only one specific node, you'd do:
{noformat}
ALTER TABLE foo WITH node_overrides = { '192.168.0.1' : { 'compaction' : {
'class' : 'LeveledCompactionStrategy' } } }
{noformat}
I'll note that I already suggested that idea on CASSANDRA-10898, but as it's
more generic than what that latter ticket is about, so creating its own ticket.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
