MySQL Bugs: #41933: Large lists of databases break initial agent data item discovery

Bug #41933	Large lists of databases break initial agent data item discovery
Submitted:	7 Jan 2009 21:08	Modified:	13 Jan 2009 16:37
Reporter:	Mark Leith	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Enterprise Monitor: Server	Severity:	S2 (Serious)
Version:	2.0.1.7125	OS:	Any
Assigned to:	Darren Oldag	CPU Architecture:	Any

Description:
Starting a new agent against an instance that contains a lot of databases breaks up the initial discovery packet (like Bug #41314), causing collections such as CPU usage (and their graphs) to fail. 

This also relates to Bug #33150.

How to repeat:
o Set up an instance with 1000 databases
o Start an agent against it
o Check whether all of the graphs get data correctly

Suggested fix:
Do not ask for the list of databases yet, they're not used in the server at the moment anyway.

patches pushed to trunk.  merge in progress to 2.0 maint tree.

don't ask for database instances in initial discovery, but utilize the server->databases drilldown mechanism already in place.

THEN --

disabled even the drill-down discovery of database instances, as
  nothing exists in MEM to use it yet, and even if it did -- the rules
  infrastructure is not very suitable to writing generic rules on database
  instances anyway.
  
  the setting to fetch DBs is controlled by a manager property setting.
  by default, it will not fetch databases or table.  then, you can optionally
  enable just database level inventory.  or, if you feel dangerous, enable
  databases AND tables.
  
  databaseInventoryLevel = NONE
  databaseInventoryLevel = DATABASE
  databaseInventoryLevel = DATABASE_TABLE
  
  perhaps, one day, when db inventory is useful, we can expose setting this
  in the UI.  for now, it would have to be backdoor'd via the repository
  or the REST property settter.

patch merged to 2.0 maint branch, awaiting build.

verified it doesn't log db instances during initial discovery in build 7.0.2.7132

An entry was added to the 2.0 changelog:

Starting a new agent against an instance that contained many databases broke up the initial discovery packet, causing collections such as CPU usage and their graphs to fail. See also Bug#33150 and Bug#41314.