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”,…
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Full text search in MongoDB
This is a custom implementation created by the MongoDB developers as a specific index type, and is due to be launched as an experimental feature in MongoDB 2.4. It has features such as: Full text search as an index type…
MongoDB Fragmentation best practices.
Q – Does data file fragmentation in MongoDB reduce the amount of data cached in memory Yes, the memory mapping approach used by MongoDB maps files directly to memory. If there is fragmentation in these files, this will be mapped…
MongoDB Triggers ?!!
1) Equivalent to RDBMS triggers in MongoDB ? There is no direct functionality available in MongoDB equivalent to triggers. However, we can achieve similar results using couple of solutions: (a) MongoDB’s “Tailable Cursors” Tailable cursors are conceptually equivalent to the…
MongoDB Monitoring script
#!/bin/bash from=”Alerts@dbversity.com” to=”dbversity@gmail.com” subject=”MongoDB Monitoring Alerts : Long running queries and No. of Open connections” echo ” Hello Team,” > /tmp/email_body.txt echo ” ” >> /tmp/email_body.txt echo “There are long running queries on the MongoDB server, please find attached txt…
How to drain a MongoDB Shard
use dbversity db.dbfry.ensureIndex( { user_id : 1 }, { unique : true }) sh.enableSharding(“dbversity”) sh.shardCollection(“dbversity.dbfry”, {“user_id”:1}) sh.startBalancer() sh.getBalancerState() sh.isBalancerRunning() use dbversity for(var i = 1; i <= 100000 ; i++){db.dbfry.insert({“user_id” : i , “name” : “bulk-inserts”, ” Iteration: ” :…
Command to know Shard distribution from mongos/router
mongos> sh.status() — Sharding Status — sharding version: { “_id” : 1, “minCompatibleVersion” : 5, “currentVersion” : 6, “clusterId” : ObjectId(“568d598d58c8ebe6f4ccaf19”) } shards: { “_id” : “rs1”, “host” : “rs1/dbversity.com:27010,dbversity.com:27011” } { “_id” : “rs2”, “host” : “rs2/dbversity.com:27020,dbversity.com:27021” } {…