.PP
An OVSDB schema has a schema version number, and an OVSDB database
embeds a particular version of an OVSDB schema.  These version numbers
take the form \fIx\fB.\fIy\fB.\fIz\fR, e.g. \fB1.2.3\fR.  The OVSDB
implementation does not enforce a particular version numbering scheme,
but schemas managed within the Open vSwitch project use the following
approach.  Whenever the database schema is changed in a non-backward
compatible way (e.g. deleting a column or a table), \fIx\fR is
incremented (and \fIy\fR and \fIz\fR are reset to 0).  When the
database schema is changed in a backward compatible way (e.g. adding a
new column), \fIy\fR is incremented (and \fIz\fR is reset to 0).  When
the database schema is changed cosmetically (e.g. reindenting its
syntax), \fIz\fR is incremented.
.PP
Some OVSDB databases and schemas, especially very old ones, do not
have a version number.
.PP
Schema version numbers and Open vSwitch version numbers are
independent.