Name

dbaugment -- Augment a Postgres database in predefined ways

Synopsys

dbaugment [option...] dbname [spec]

Description

dbaugment is a utility for augmenting a Postgres database with various standard attributes and procedures, such as automatically maintained audit columns. The augmentations are defined in a YAML-formatted spec file.

The following is an example of a specification file:

augmenter:
  columns:
    modified_date:
      not_null: true
      type: date
schema public:
  table t1:
    audit_columns: default
  table t3:
    audit_columns: modified_only

The specification file lists each schema, and within it, each table to be augmented. Under each table the following values are currently recognized:

• audit_columns: This indicates that audit trail columns are to be added to the table, e.g., a timestamp column recording when a row was last modified.

The first section of the specification file, under the augmenter header, lists configuration information. This is in addition to the built-in configuration objects (see predef-aug).

dbaugment first reads the database catalogs. It also initializes itself from predefined configuration information. dbaugment then reads the specification file, which may include additional configuration objects, and outputs a YAML file, including the existing catalog information together with the desired enhancements. The YAML file is suitable for input to yamltodb to generate the SQL statements to implement the changes.

Options

dbaugment accepts the following command-line arguments (in addition to the cmdargs):

dbname

Specifies the name of the database whose schema is to augmented.

spec

Location of the file with the augmenter specifications. If this is omitted, the specification is read from the program's standard input.

Examples

To augment a database called moviesdb according to the specifications in the file movies.yaml:

dbaugment moviesdb movies.yaml

To add a column named updated to table public.film to hold the date and time each row was inserted or updated, create a YAML specification file, say film.yaml as follows:

augmenter:
  columns:
    modified_timestamp:
      name: updated
schema public:
  table film:
    audit_columns: modified_only

The first four lines configure the predefined modified_timestamp audit column to use the name updated instead. The last three lines direct dbaugment to apply the predefined modified_only audit column to the film table.

Then run the following command to generate the resulting database specification, alter the table and create the needed trigger and function.

dbaugment moviesdb film.yaml | yamltodb moviesdb -u

See Also

predef-aug