make4db 0.1.3

GNU Make like tool for database scripts

make4db

make like tool for databases.

Like the traditional make tool, make4db builds any modified database scripts, in most cases DDLs, and dependent database scripts in dependency order. For example, when a table DDL is modified, its DDL is evaluated, and then any views that reference the modified table are evaluated, and so on.

One key difference between the traditional make tool and db4make is, that db4make does not rely on file timestamps to detect changes; but instead uses cryptographic hashes.

Features

• build all changed and their dependent objects in the dependency order (make)
• build only specific objects and their references (if changed) in the dependency order (make <target>)
• touch mode -- mark objects as built, without running SQLs (make -t)
• preview mode -- only show objects that would be executed (make -n)
• rebuild unconditionally (make -B)
• when supported by the DBMS, help obtain object dependencies
• in case of a failure, keep building scripts that are not dependent on the failing scripts (make -k)

Installation

Use pip (pipx recommended) for installation. In addition to make4db package, a database-provider package for m4db must be installed. Available database-provider packages:

1. make4db-duckdb
2. make4db-postgres
3. make4db-snowflake

Usage

m4db is the primary tool. It is used for building changed DDLs and their dependent objects in the correct order.

Use m4db --help to list all available options. Some of the important options are listed below:

• --ddl-dir: root directory containing all DDLs. It is recommended to use VCS such as git to store DDLs
• --tracking-dir: a directory to store DDL execution status. Although execution status is considered persistent information, this directory is not typically version-controlled. There might be different tracking directories that represent different environments, such as dev, prod etc.
• --out-dir: directory to DDL execution logs

Companion tools

Besides the main tool (m4db), the following tools are also available:

• m4db-refs: show or manage object dependency hierarchy
• m4db-gc: garbage collect outdated, orphaned files
• m4db-dbclean: allows cleaning up outdated database objects by generating DROP statements. Note: only available for some databases
• m4db-cache: allows pre-computing cryptographic hash for large repositories

Storing DDLs

• DDLs are stored as plain text in single-level deep folders.

• Folder names are used to infer schema name, and file names are used to infer object names. File and folder names are always in lower-case, but converted to upper-case to derive schema and object names

• File names consist of a base name and extension.

  • Base name must match the object name (except filename must be all lower-case).
  • File extension must be either .sql or .py
  • File names that start with . (period) are ignored, and so are any .py files that start with _.

• Files that have .sql extension must contain one or more valid SQL statements.

• Files that have .py extension must be a top-level Python script and must contain a function named sql returning one or more SQL statements as string. The following are the two valid function signatures.

  def sql(name: str, replace: bool) -> str | Iterable[str]:
      """Dynamically build and return SQL statement(s)
  
     Args:
     name: name of the object being created (or replaced). note: name is qualified with the schema name
     replace: true if m4db is running in replace mode, that is, --replace option was specified at run-time
  
     Returns:
     A single SQL statement as `str`; or multiple SQL statements as `Iterable[str]`
      """
  

  def sql(session, name: str, replace: bool) -> str | Iterable[str]:
      """Dynamically build and return SQL statement(s)
  
     Args:
     session: an active database session (must not be closed)
     name: name of the object being created (or replaced). note: name is qualified with the schema name
     replace: true if m4db is running in replace mode, that is, --replace option was specified at run-time
  
     Returns:
     A single SQL statement as `str`; or multiple SQL statements as `Iterable[str]`
      """
  

Limitations

• only manages schema-level objects (does not manage databases, schemas, or permissions)
• does not manage cross-database objects (assumes databases are "environments")
• object dependency management, depending on the database support, is semi-automatic
• change detection is based on the file content

Technical details

• Unlike the traditional make utility, make4db relies on the cryptographic hash of files to detect changes.
• make4db is database agnostic and requires separate database provider module to function
• make4db relies on object references (for example, references of a view being other tables/views) to determine what objects need to be (re)build
  • object references are stored along with the database scripts in a hidden folder (.m4db in the project-level folder)
  • m4db-refs is a helper tool that can, for selected databases, automatically generate object references