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Breaking changes between 26compat and legacy

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Tyler Brock edited this page Jul 17, 2014 · 14 revisions

Overview

The 26compat release series tracks the server 2.6 releases one-to-one. As a result, it receives only bugfixes and small updates necessary to keep it building in isolation.

The legacy release series, on the other hand, is under active development. Our philosophy is to keep the legacy branch as close to the 26compat branch as is reasonable, but that when weighing new features against compatibility, we will choose new features. As a result the legacy branch is not 100% source compatible with the 26compat branch.

This page attempts to serve as a transition guide for those users looking to migrate from the 26compat branch to the legacy branch. Note that it does not discuss new features in detail and simply points to the per-release notes.

NOTE: This is a living document, and tracks the current state of the legacy branch. While we have attempted to capture the big ticket breakages here, there are likely to be small ones that we have missed. The C++ driver developers would appreciate it greatly if, when you are moving from 26compat to legacy, you find issues not tracked here: please send us a pull request so we can keep this page up to date and useful.

Warning: The legacy branch is currently unstable and under active development.

Breaking Changes

Changes to the build system

  • The --full flag is no longer required, and it is an error to specify it.
  • The --d and --dd flags have been removed. Use the --opt and --dbg flags instead.
  • The --use-system-boost flag is no longer required, and it is an error to specify it.
  • All ABI affecting macros are now defined in a generated config.h header that is automatically included from dbclient.h and bson.h.
  • Many server specific build options (that were unlikely to have been used when building the driver) have been removed.
  • The default installation prefix is now build/install, rather than /usr/local.
  • All build artifacts are now captured under the build directory.

Changes to APIs

  • The mongo::BSONBuilderBase class has been removed and is no longer a base class of mongo::BSONObjBuilder or mongo::BSONArrayBuilder
  • The mongo::OpTime class no longer offers the now and related synchronized methods.
  • The globalServerOptions and globalSSLOptions objects and their classes have been removed. All driver configuration should be done through the new mongo::client::Options object.
  • The RamLog, RotatableFileAppender, and Console classes have been removed from the logging subsystem.
  • In addition, many auxiliary types, functions, and headers that were either unused, or minimally used, have been removed from the distribution.
  • The ensureIndex and related methods have been removed. The replacement is the new createIndex method.

Behavior Changes

  • The driver is now unlikely to function correctly unless mongo::client::initialize is invoked before using the driver APIs.
  • The driver no longer logs any output by default. You may configure and inject a logger to re-enable logging. See src/mongo/client/examples/clientTest.cpp for an example of how to enable logging.
  • Writes are now "acknowledged" by default. In all previous releases the default write concern was “unacknowledged”. This change may have performance and behavior implications for existing applications that did not confirm writes. You can read more about the change here.

Improvements

Please see the release notes for the individual legacy branch releases for details on improvements in each release:

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