yamltodb - YAML to Database¶
yamltodb – generate SQL statements to update a PostgreSQL database to match the schema specified in a YAML file
yamltodb [option...] dbname [spec]
yamltodb is a utility for generating SQL statements to update a PostgreSQL database so that it will match the schema specified in an input YAML formatted specification file.
For example, given the input file shown under dbtoyaml - Database to YAML, yamltodb outputs the following SQL statements:
CREATE SCHEMA s1; CREATE TABLE t1 ( c1 integer NOT NULL, c2 smallint, c3 boolean DEFAULT false, c4 text); CREATE TABLE s1.t2 ( c21 integer NOT NULL, c22 character varying(16)); ALTER TABLE s1.t2 ADD CONSTRAINT t2_pkey PRIMARY KEY (c21); ALTER TABLE t1 ADD CONSTRAINT t1_pkey PRIMARY KEY (c1); ALTER TABLE t1 ADD CONSTRAINT t1_c2_fkey FOREIGN KEY (c2) REFERENCES s1.t2 (c21);
yamltodb accepts the following command-line arguments (in addition to the Common Command Line Options):
Specifies the name of the database whose schema is to analyzed.
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
--multiple-filesoption is used, that takes precedence.
Specifies that input should be taken from YAML specification files present in a two-level (metadata) directory tree. See Multiple File Output under dbtoyaml - Database to YAML for further details.
Compare only a schema matching schema. By default, all schemas are compared. Multiple schemas can be compared by using multiple
Wrap the generated statements in BEGIN/COMMIT. This ensures that either all the statements complete successfully, or no changes are applied.
Execute the generated statements against the database mentioned in dbname. This implies the
When generating SQL, use delimited (quoted) identifiers around reserved words used as identifiers, e.g., a table named “order”. Normally, only identifiers with embedded spaces or other disallowed characters are quoted.
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
--revertoption generates a
CREATE TABLEwith all the columns, constraints and other objects associated with the table being dropped.
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
yamltodb --update mymovies moviesdb.yaml
To generate the statements directly from the ouput of
dbtoyaml (against a different database), with statements
enclosed in a single transaction, and save the statements in a file
dbtoyaml devmovies | yamltodb -1 mymovies -o mymovies.sql