Commits

What is a Commit?

A commit signals to Doltgres that you would like to save the state of the current database permanently for future reference. In practice, this stores the root hash (or reference) of the database in a graph of all the commits with a link to its parent commit. If the commit is a merge commit, the commit will have multiple parents.

Commit hashes are SHA-256 encoded hashes of the entire database. Commit hashes look liket5d5inj4bpc1fltrdm9uoscjdsgebaih. These are abbreviations of the entire hash that Doltgres understands. When referring to a specific commit, this is the identifier you use.

A Doltgres commit is different from a standard SQL transaction commit. Doltgres supports both which can be a bit confusing.

How to use Commits

Doltgres uses commits as the basis of comparison between two versions of a database. You can ask Doltgres to do things like:

• Show me the differences between these two commits

• Give me the common ancestor of these two commits

• Make my current database look like this commit

• Show me the difference between my current database and the last commit

• Show me all the commits since this database was created

• Show me who created this commit and the message they left when he or she made it

You should make a commit when you want to be able to use the current version of the database to do one of the above things.

To create a commit, you call the DOLT_COMMIT() function. A user and commit message are required. Your user is defined in configuration. You provide a commit message via the user interface.

Difference between Git Commits and Doltgres commits

Git commits and Doltgres commits are very similar in purpose and practice.

Example

create table docs_sql (pk int, primary key(pk));
select dolt_commit('-a', '-m', 'Added docs_sql example table. Use -a to stage all changes for commit ie. skip dolt add');
+-------------------------------------------------------------------------------------------------------------------+
| dolt_commit('-a', '-m', 'Added docs_sql example table. Use -a to stage all changes for commit ie. skip dolt add') |
+-------------------------------------------------------------------------------------------------------------------+
| v42og53ru3k3hak3decm23crp5p6kd2f                                                                                  |
+-------------------------------------------------------------------------------------------------------------------+

Creating an empty commit

select dolt_commit('--allow-empty', '-m', 'This is a commit');
+--------------------------------------------------------------+
| dolt_commit('-a', '--allow-empty', '-m', 'This is a commit') |
+--------------------------------------------------------------+
| u73s2mb1ho4mj1ldkof939vampo93bld                             |
+--------------------------------------------------------------+