Question : – ============================================ I’ve a quick question on Covered/IndexOnly Index – it’s saying query goes to index collection – not to actual collection; but I don’t see any entries in system.indexes collections except 2 – I’m little confused here….
By default MongoDB displays 20 records in the results for any DB query (which results more than 20 records ) & you can see the next set of result by pressing ‘it’ (iteration) in the prompt. However, you can change the default…
Orphaned document In a sharded cluster, orphaned documents are those documents on a shard that also exist in chunks on other shards as a result of failed migrations or incomplete migration cleanup due to abnormal shutdown. Delete orphaned documents using…
Determining Which DB Instance You Are Connected To You can determine which DB instance in an Aurora DB cluster that a connection is connected to by checking the innodb_read_only global variable, as shown in the following example. SHOW GLOBAL VARIABLES…
Monitoring Aurora Replication Engine DB Instance Status CPU Current Activity Class VPC Multi-AZ Replication Role Aurora my-auroradb-cluster available 0.78% 1 Connections db.r3.xlarge…
Testing Amazon Aurora Using Fault Injection Queries You can test the fault tolerance of your Amazon Aurora DB cluster by using fault injection queries. Fault injection queries are issued as SQL commands to an Amazon Aurora instance and they enable…
SysBench is a modular, cross-platform and multi-threaded benchmark tool for evaluating OS parameters that are important for a system running a database under intensive load. The idea of this benchmark suite is to quickly get an impression about system performance…
SysBench: System evaluation benchmark Why ? The idea is to quickly get an impression about system performance for MySQL usage without setting up complex benchmark and even without installing MySQL. In some cases this is very helpful. This is also the…
Elasticsearch users have delightfully diverse use cases, ranging from appending tiny log-line documents to indexing Web-scale collections of large documents, and maximizing indexing throughput is often a common and important goal. While we try hard to set good general defaults…
Shell script to run a 3 sharded cluster (3 ReplicaSet) on a single server. [root@dbversity.com bin]# cat shard_creation_script.sh ##### Killing the existing Mongo processes ################ for i in `ps -ef | egrep ‘shardsvr|configsvr|replSet|configdb’ | grep -v egrep | awk -F”…