This feature release of the Ruby MongoDB driver includes the following new features:

• RUBY-2130 Move the query cache into the driver and improve its implementation
• RUBY-2093 Non-stapled OCSP Support
• RUBY-2211 Atlas Data Lake support: Use namespace returned from find command in getMore
• RUBY-2020 Set explain verbosity from Mongo::Collection::View::Explainable
• RUBY-2346 Mixed case read preference tag names are now supported

The following minor improvements were made:

• RUBY-1524 Driver session pools are now cleared when reconnecting the client
• RUBY-2399 Provide better diagnostics when inserting non-hashes
• RUBY-2349 estimated_document_count now raises an exception when it is given find conditions
• RUBY-2419 Eliminated driver spamming Server description for address changed from 'standalone' to 'standalone' log messages
• RUBY-2299 Support per-operation write concern for database and collection write methods
• RUBY-2356 Set default logger level to info
• RUBY-2357 Standardize on STDOUT over $stdout
• RUBY-2289 Display monitoring state in client summary
• RUBY-1932 Specify timeouts for DNS queries for SRV URIs

The following bugs were fixed:

• RUBY-2421 Auth mechanism properties not downcased when client is created with host and Ruby options with symbol key
• RUBY-2345 Validate document size on pre-3.6 servers
• RUBY-2166 Mark servers unknown when connections experience network errors during setup
• RUBY-1632 Handle bogus/invalid read concern sub-options

Support for Ruby versions 2.3 and 2.4 has been deprecated in this release. Read more about this change here.