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”,…
Full Text Search of Dialogues with Apache Lucene: A Tutorial
Apache Lucene is a Java library used for the full text search of documents, and is at the core of search servers such as Solr and Elasticsearch. It can also be embedded into Java applications, such as Android apps or web backends. While Lucene’s…
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…
Meet Volt, A Promising Ruby Framework For Dynamic Applications
Volt is a Ruby framework designed for data rich applications. Both the server and client sides are written in Ruby (which is then compiled to JS using OPAL), so this allows the developer to write very dynamic applications without having…