## Major changes in 2.0

- Database backend switched from LevelDB to SQLite. There is a migration on
  first launch which can be lengthy for larger setups. The new database is
  easier to understand and maintain and, hopefully, less buggy.

- Deleted items are no longer kept forever in the database, instead they are
  forgotten after six months. If your use case require deletes to take
  effect after more than a six month delay, set the
  `--db-delete-retention-interval` command line option or corresponding
  environment variable to zero, or a longer time interval of your choosing.

- Modernised command line options parsing. Old single-dash long options are
  no longer supported, e.g. `-home` must be given as `--home`. Some options
  have been renamed, others have become subcommands. All serve options are
  now also accepted as environment variables. See  `syncthing --help` and
  `syncthing serve --help` for details.

- Rolling hash detection of shifted data is no longer supported as this
  effectively never helped. Instead, scanning and syncing is faster and more
  efficient without it.

- A "default folder" is no longer created on first startup.

- Multiple connections are now used by default between v2 devices. The new
  default value is to use three connections: one for index metadata and two
  for data exchange.

- The following platforms unfortunately no longer get prebuilt binaries for
  download at syncthing.net and on GitHub, due to complexities related to
  cross compilation with SQLite:

  - dragonfly/amd64
  - illumos/amd64 and solaris/amd64
  - linux/ppc64
  - netbsd/*
  - openbsd/386 and openbsd/arm
  - windows/arm