[NoSQL] the place of equalizer information in mongo_detail.py

The idea of processing equalizer information in [ToolsForMongo] mongo_detail.py

First, take a look at the db.settings.find ({'_ id':'balancer'}) output in several typical situations:

1. After creating the mongos, when the balancer is never set:

Mongos > var x = db.settings.findOne ({'_ id':'balancer'}) mongos > x = = nulltruemongos > sh.getBalancerState () true

two。 After creating the mongos, the balancer was manually closed for some reason

Mongos > db.settings.findOne ({'_ id':'balancer'}) {"_ id": "balancer", "mode": "off", "stopped": true} mongos > sh.getBalancerState () false

3. The running time period of balancer is set, but the current time is not in it

Mongos > var x = db.settings.findOne ({'_ id':'balancer'}) mongos > x {"_ id": "balancer", "stopped": true, "activeWindow": {"start": "00:00", "stop": "06:00"} mongos > sh.getBalancerState () false

4. The running time period of balancer is set, in which the current time is

Mongos > var x = db.settings.findOne ({'_ id':'balancer'}) mongos > x {"_ id": "balancer", "stopped": false, "activeWindow": {"start": "00:00", "stop": "22:00"} mongos > sh.getBalancerState () true

Take a look at the js code in the official mongo shell.

Mongos > sh.getBalancerStatefunction (configDB) {if (configDB = = undefined) configDB = sh._getConfigDB (); var x = configDB.settings.findOne ({_ id: "balancer"}); if (x = = null) return true; return! x.stopped;}

1. First deal with the case that configDB is not the default config library

2.x = = null indicates that balancer has never been set above and is enabled by default

3. Invert the .stopped item in the return value to get whether it is running

Mongos > sh.isBalancerRunningfunction (configDB) {if (configDB = = undefined) configDB = sh._getConfigDB (); var x = configDB.locks.findOne ({_ id: "balancer"}); if (x = = null) {print ("config.locks collection empty or missing. Be sure you are connected to a mongos"); return false;} return x.state > 0;}