Why MongoDB Compass ?!
Know your data with seamless schema visualization MongoDB Compass analyzes your documents and displays rich structures within your collections in a simple and intuitive GUI. It allows you to quickly visualize and explore your schema to understand the frequency, types…
set/unset the fields with another fields in mongo
Question : How can I update a field with another field value in the same document (in both array & embedded sub documents) From the attached JSON document, I would like to update ‘analyticUsers.geid’ to : ‘analyticUsers._id’ & tried all…
MongoDB WT with ext4 Filesystem and its performance issues.
Currently MongoDB Inc., is lacking in a comprehensive explanation of the issues that can arise with WT when running on EXT4. Specifically, details on what the issue is, under what conditions it can manifest, and what the symptoms are. They’ve…
Tag-aware Sharding commands
use dbversity db.nosql.ensureIndex({“mongodb” : 1}) db.rbdms.ensureIndex({“oracle” : 1}) db.newsql.ensureIndex({“memsql” : 1}) sh.enableSharding(“dbversity”) use admin db.runCommand({shardCollection: “dbversity.nosql”, key : {“mongodb”:1}}) db.runCommand({shardCollection: “dbversity.rbdms”, key : {“oracle”:1}}) db.runCommand({shardCollection: “dbversity.newsql”, key : {“memsql”:1}}) sh.startBalancer() sh.isBalancerRunning() sh.getBalancerState() for (var i=0; i
WiredTiger’s weird bugs
MognoDB Inc has identified a bug in MongoDB 3.0 where, under very rare circumstances, an integer overflow condition may cause a replica set to become read-only. While this bug does not cause any data loss, it has the potential to cause…
MongoDB ReplSetTest()
replSetTest is an internal command that is not enabled by default. replSetTest must be enabled by using –setParameter enableTestCommands=1 on the mongod command line. replSetTestcannot be enabled during run-time. > var rst = new ReplSetTest( { name: ‘rsTest’, nodes:…
MongoDB Sharding Best Practices
MongoDB Sharding is a complex operation for the db cluster and below are the reasons to shard. Whole data doesn’t fit on one server’s storage (Disk Space) Disk IO & CPU Working set doesn’t fit in one server’s RAM Write…
Using $min and $max on shard key doesn’t target queries ?
Using $gte and $lt on the shard key fields inside a query will cause it the query to be targeted to only the appropriate shards. However, using the $min and $max query operators (while hinting on the shard key) doesn’t…
Shard key can not exceed 128 characters ?
Shard key can not exceed 128 characters, if you try so Mongo doesn’t create an Index for that Shard key and as a result such sharded collection without index for sharding key will case performance degradation. mongos> use sharding_test;…
$setOnInsert with a shard key – not possible ?
Having the collection empty, when trying to do an upsert using $setOnInsert on a shard key I get the following error: Can’t modify shard key’s value. field: card: 1.0 collection: vizvid.total_video_views mongos> db.dbversity.status() { “sharded” : true, “ns” : “dbfry.dbversity”,…