“We recommend that you start with a high threshold value.”
Amazon continues to add extra supports to its non-relational database store DocumentDB with the addition of slow queries logging.
Slow queries logging allows user to monitor their slowest queries in the cluster. This helps to improve overall performance of the cluster and the individual query.
Once the user has enabled a set profiler for the query the system will monitor operations and if any queries run longer than the customer-defined threshold, set at 100ms by default, the system will log their execution time and send an alert to the CloudWatch Logs.
The system will log details such as profiled command line, plan summary and client metadata.
AWS notes that: “When enabled, profiler utilizes additional resources in your cluster. We recommend that you start with a high threshold value (i.e., 500ms) and gradually lower the value to identify slow operations. Starting with a threshold value of 50ms can cause performance issues on your cluster for high throughput applications. Profiler is enabled at the cluster level and is performed on all instances and databases in a cluster.”
Amazon DocumentDB and MongoDB
DocumentDB is a non-relational databases that stores documents in flexible, binary representations called BSON (Binary JSON). This means fields can vary from document to document and data structure can be changed over time; as opposed to relational database management system like Oracle’s MySQL, which store data in tables and use structured query language for database access.
Amazon DocumentDB uses MongoDB’s 2017 open source-licensed 3.6 API to ape the responses that a MongoDB client expects from a MongoDB server. This allows customers to use their existing MongoDB drivers. DocumentDB automatically scales up to 64TB of data per cluster.
MongoDB itself is now on 4.0 and is no longer fully open source. Last year MongoDB changed their licensing agreements from a GNU AGPLv3, (companies who wish to use their code for commercial reasons should open source their software), to a Server Side Public License (SSPL).
Last January a MongoDB spokesperson told Computer Business Review that: “Customers want the real thing rather than some feature-limited imitation, and no customer is demanding to be locked into a single vendor’s ecosystem… Our initial testing shows that DocumentDB has the same shortcomings in functionality as similar imitation products that have been on the market for years, and those have not slowed the growth of MongoDB.”
“Important recent MongoDB features such as multi-document ACID transactions, change streams and global clusters are all absent, as are a host of older core capabilities, such as joins and even schema support–features MongoDB has had for years. Ironically, while it was the massive popularity and momentum of MongoDB that drove AWS to make this announcement, we believe this announcement will only… drive other AWS customers to the real MongoDB global cloud database, MongoDB Atlas.”