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Code Issues Releases Activity

db.getReplicationInfo() in shell

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Dwight 2009-02-05 15:41:34 -05:00
parent 9b7f4d830d
commit 50538e88c3
1 changed files with 62 additions and 0 deletions
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62
shell/db.js
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@ -119,6 +119,7 @@ DB.prototype.help = function() {
print("\tdb.runCommand(cmdObj) run a database command. if cmdObj is a string, turns it into { cmdObj : 1 }");
print("\tdb.addUser(username, password)");
print("\tdb.createCollection(name, { size : ..., capped : ..., max : ... } )");
print("\tdb.getReplicationInfo()");
print("\tdb.getProfilingLevel()");
print("\tdb.setProfilingLevel(level) 0=off 1=slow 2=all");
print("\tdb.eval(func, args) run code server-side");
@ -325,3 +326,64 @@ DB.prototype.toString = function(){
return this._name;
}
/**
Get a replication log information summary.
<p>
This command is for the database/cloud administer and not applicable to most databases.
It is only used with the local database. One might invoke from the JS shell:
<pre>
use local
db.getReplicationInfo();
</pre>
It is assumed that this database is a replication master -- the information returned is
about the operation log stored at local.oplog.$main on the replication master. (It also
works on a machine in a replica pair: for replica pairs, both machines are "masters" from
an internal database perspective.
<p>
* @return Object timeSpan: time span of the oplog from start to end if slave is more out
* of date than that, it can't recover without a complete resync
*/
DB.prototype.getReplicationInfo = function() {
if( "local" != this )
return { errmsg : "this command only works for database local" };
var result = { };
var db = this;
var ol = db.system.namespaces.findOne({name:"local.oplog.$main"});
if( ol && ol.options ) {
result.logSizeMB = ol.options.size / 1000 / 1000;
} else {
result.errmsg = "local.oplog.$main, or its options, not found in system.namespaces collection";
return result;
}
var firstc = db.oplog.$main.find().sort({$natural:1}).limit(1);
var lastc = db.oplog.$main.find().sort({$natural:-1}).limit(1);
if( !firstc.hasNext() || !lastc.hasNext() ) {
result.errmsg = "objects not found in local.oplog.$main -- is this a new and empty db instance?";
result.oplogMainRowCount = db.oplog.$main.count();
return result;
}
var first = firstc.next();
var last = lastc.next();
{
var tfirst = first.ts;
var tlast = last.ts;
if( tfirst && tlast ) {
tfirst = tfirst / 4294967296; // low 32 bits are ordinal #s within a second
tlast = tlast / 4294967296;
result.timeDiff = tlast - tfirst;
result.timeDiffHours = result.timeDiff / 3600;
result.tFirst = (new Date(tfirst*1000)).toString();
result.tLast = (new Date(tlast*1000)).toString();
result.now = Date();
}
else {
result.errmsg = "ts element not found in oplog objects";
}
}
return result;
}