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yamltodb - YAML to Database
===========================
Name
----
yamltodb -- generate SQL statements to update a Postgres database to
match the schema specified in a YAML file
Synopsis
--------
::
yamltodb [option...] dbname [spec]
Description
-----------
:program:`yamltodb` is a utility for generating SQL statements to
update a Postgres database so that it will match the schema
specified in an input `YAML <http://yaml.org>`_ formatted
specification file.
For example, given the input file shown under :doc:`dbtoyaml`,
:program:`yamltodb`, when run against a newly-created database,
outputs the following SQL statements::
CREATE SCHEMA s1;
ALTER SCHEMA s1 OWNER TO bob;
GRANT ALL ON SCHEMA s1 TO bob;
GRANT ALL ON SCHEMA s1 TO alice;
CREATE TABLE t1 (
c1 integer NOT NULL,
c2 smallint,
c3 boolean DEFAULT false,
c4 text);
ALTER TABLE t1 OWNER TO alice;
CREATE TABLE s1.t2 (
c21 integer NOT NULL,
c22 character varying(16));
ALTER TABLE s1.t2 OWNER TO bob;
GRANT ALL ON TABLE s1.t2 TO bob;
GRANT SELECT ON TABLE s1.t2 TO PUBLIC;
GRANT INSERT, DELETE, UPDATE ON TABLE s1.t2 TO alice WITH GRANT OPTION;
GRANT INSERT ON TABLE s1.t2 TO carol;
ALTER TABLE t1 ADD CONSTRAINT t1_c2_check CHECK (c2 > 123);
ALTER TABLE t1 ADD CONSTRAINT t1_pkey PRIMARY KEY (c1);
ALTER TABLE s1.t2 ADD CONSTRAINT t2_pkey PRIMARY KEY (c21);
ALTER TABLE t1 ADD CONSTRAINT t1_c2_fkey FOREIGN KEY (c2) REFERENCES s1.t2 (c21);
Options
-------
:program:`yamltodb` accepts the following command-line arguments (in
addition to the :doc:`cmdargs`):
.. program:: yamltodb
**dbname**
Specifies the name of the database whose schema is to analyzed.
**spec**
Specifies the location of the YAML specification. If this is
omitted or specified as a single or double dash, the specification
is read from the program's standard input. However, if the
:option:`--multiple-files` option is used, that takes precedence.
.. cmdoption:: -m, --multiple-files
Specifies that input should be taken from YAML specification files
present in a two-level (metadata) directory tree. See `Multiple
File Output` under :doc:`dbtoyaml` for further details.
.. cmdoption:: -n <schema>
--schema <schema>
Compare only a schema matching `schema`. By default, all schemas
are compared. Multiple schemas can be compared by using multiple
:option:`-n` switches.
.. cmdoption:: -1
--single-transaction
Wrap the generated statements in BEGIN/COMMIT. This ensures that
either all the statements complete successfully, or no changes are
applied.
.. cmdoption:: -u, --update
Execute the generated statements against the database mentioned in
**dbname**. This implies the :option:`--single-transaction`
option.
.. cmdoption:: --revert
Generate SQL in reversion mode, that is, to undo the changes that
would normally be generated. For example, if without this option,
the SQL would be a ``DROP TABLE``, the :option:`--revert` option
generates a ``CREATE TABLE`` with all the columns, constraints and
other objects associated with the table being dropped.
This option is experimental and currently has only been
implemented for schemas and sequences.
Examples
--------
Given a YAML file named ``moviesdb.yaml``, to generate SQL statements
to update a database called `mymovies`::
yamltodb mymovies moviesdb.yaml
To generate the statements as above and immediately update `mymovies`::
yamltodb mymovies moviesdb.yaml | psql mymovies
or::
yamltodb --update mymovies moviesdb.yaml
To generate the statements directly from the output of
:program:`dbtoyaml` (against a different database), with statements
enclosed in a single transaction, and save the statements in a file
named ``mymovies.sql``::
dbtoyaml devmovies | yamltodb -1 mymovies -o mymovies.sql