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#+Title: DBDoc (Database Schema Documenter)

Document your database schema (tables and columns), because your team will thank you, and this makes it easy.

DBDoc enables you to describe (via generated =COMMENT ON= statements) your relational database schema in a simple text file, which is easy for developers/DBAs to edit and search in the repo. The docs (each a snippet of a sentence or two) are then:

• viewable in an SQL client like DBeaver or Datagrip (the main use case) as tooltips and in other views

• greppable in your code base

• web-publishable as docs, enabling other stakeholders (eg, Product people) to view DB documentation (in Confluence or wherever)

• presentable one table at a time for brainstorming, explaining, etc, with an org presenter, like [[https://github.com/eschulte/epresent][epresent]] or [[https://github.com/takaxp/org-tree-slide][org-tree-slide]] (screenshot at bottom)

It works by converting a very minimal ORG-valid and -prescribed syntax (top-level bullets, single paragraphs, and definition lists) into (long) [[https://www.postgresql.org/docs/current/sql-comment.html][SQL =COMMENT ON= statements]], which can be run automatically on your database (via migration or sourced or however you like).

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(See far below for more screenshots.)

** Example dbdoc.org file

The following shows an example =dbdoc.org= file describing a movie store rental database and a few of its tables: =film= (containing =title= and =description= columns), =movie= (a deprecated table with no columns documented), and =actor=. Notice: the hyphens instead of underscores, newlines before definitions, other indentation.

An example translation then is from:

#+begin_src org #+Title: Pagila Movie Store Rental Database

This is the "dbdoc" description file for the Pagila database. See the [[https://github.com/micahelliott/dbdoc][dbdoc README]] for more detailed instructions on its purpose and expanding it. This file contains short documentation for any tables and columns that could use even the slightest bit of explanation.

Edit this file whenever you make schema changes. And be a good citizen by helping to grow this file any time you're touching a table! The remainder of this file will be used processed into comment descriptions that will be visible in your SQL client, and can also be exported as HTML.

• FILM

A film, aka movie, is released initially in theaters, and then available to movie /stores/, at which point they become available to the DB.

• title :: The full name of the film, including things like sub-title and part in a series; does not include language

• description :: A brief synopsis (catchy prose) about the plot

• MOVIE

DEPRECATED: replaced by =film=

• ACTOR

An actor is very simple and non-comprehensive table to record the main headlining /stars/ of the film. All fields are obvious. Note that there may be duplicate actors that use slightly different names on occasion. #+end_src

to an SQL migration file containing:

#+begin_src sql COMMENT ON TABLE film IS 'A film, aka movie …'; COMMENT ON COLUMN film.title IS 'The full name …'; … COMMENT ON TABLE movie IS 'DEPRECATED: replaced …'; … #+end_src

Compared to the ORG version, that SQL is pretty ugly – editing (quoting, line-length/newlines, indentation, formatting) becomes quite difficult. That’s why this tiny tool exists.

There is a testable =docs/dbdoc.org= example (and its generated SQL migration file =resources/migrations/20210804162056-dbdoc.up.sql=) in this repo that was written to minimally describe the [[https://github.com/devrimgunduz/pagila][pagila toy database]]. Just run =dbdoc.clj= in the root of this repo to try it out!

** Installation

• Install [[https://github.com/babashka/babashka#installation][Babashka]].
• Clone this repo and put its root on your =PATH=.

Now you're ready to run =dbdoc.clj= from anywhere, and that's all there is to it! Not even any CLI options. :)

** Documentation Process

*** One time only

• Create a single living .org file in your repo, eg, =docs/dbdoc.org= for growing docs for your tables.

• Assuming you haven't already somehow written a =COMMENT= for your DB, turn a SME analyst type or long-time developer or DBA in your company loose to write up a bunch of notes in the org file. Then edit a bit to ensure it's valid ORG that DBDoc can handle..

• Set up env vars to change default file locations (optional, not well tested):

  #+begin_src shell export DBDOC_ORG=docs/dbdoc.org export DBDOC_SQL=resouces/migrations/-dbdoc.up.sql export DBDOC_HTML=docs/dbdoc.html #+end_src

*** Continually (this is the only real process)

1. Keep describing as many tables and columns as you see fit in your =docs/dbdoc.org= file. Every time a developer changes or adds a field or table, they also put a sentence or two describing its purpose in the org file.

2. Run =dbdoc.clj= to generate a time-stamped file like =resources/migrations/20201027000000-dbdoc.up.sql=. IMPORTANT!! Don't forget this step! (You don't need all the developers on the teams do this, so long as /someone/ does the generation/migrating once in a while.)

3. Commit both the org and migration files.

*** Optional

• Generate HTML (from command line [[https://pandoc.org/][with Pandoc]] or [[https://stackoverflow.com/a/22091045/326516][Emacs]]) and publish the new version to some site your company views (optional, see =org2conflu.zsh= script).

• If your migrations aren't automatic as part of your CI, run your migration (or just load the new SQL file if you don't do migrations).

** Table Documentation Best Practices

• Don’t need to be comprehensive and document every field when names make them obvious
• Add an example datum for a column
• Used-by references: other tables (probably not FKs) and code areas
• Gotchas/quirks
• Add characteristic tags: deprecated/defunct, xl, hot, new, static, performance, donttouch, dragons

** Showing Comments in Clients

• psql: =\d+=
• [[https://dataedo.com/kb/tools/dbeaver/how-to-view-and-edit-table-and-column-comments][dbeaver]] (HIGHLY RECOMMENDED!! the docs pop up everywhere)
• [[https://eggerapps.at/postico/][postico]] (see the Structure tab, as shown is screenshot)
• [[https://postgrest.org/en/v7.0.0/api.html#openapi-support][postgrest/swagger]]
• [[https://dataedo.com/kb/tools/pgadmin/how-to-view-and-edit-table-and-column-comments][pgadmin]]
• [[https://dataedo.com/kb/tools/datagrip/how-to-view-and-edit-table-and-column-comments][datagrip]] ([[https://stackoverflow.com/questions/66129447/how-to-show-column-and-table-comment-in-jetbrains-datagrip][how to enable]])

** Read on if you want more details...

*** Transformations

The parser is really limited and rigid and wants to see a table description paragraph for every table you wish to document. So, if you want to document some column in a table, you must also provide at least a tidbit sentence for the table too. It's not a good parser so just be careful. Alignment/indentation is important too, so follow the example format precisely – this is a tiny subset of actual org.

Org uses underscores for italic, and it’s tedious enough to have to wrap every DB entity in equals (+=+) in org to escape them, so they should instead be documented with hyphens (=-=) (though this isn’t required). IOW, all ORG hyphenated variables (eg, =my-var-name=) become underscores in SQL (=my_var_name=). So prefer to use =my-var-name= in the ORG description.

It you use “straight” apostrophes ('), they’ll be converted to curlies so as not to need SQL string escaping (and be prettier).

*** Git Diffs

The =dbdoc.clj= script looks for an old migration file called =-dbdoc.up.sql= and renames it (via =git-move=) to a present timestamp. This enables Git to see the the new migration as simply a change from the last run, and so you can easily see the before/after diff. This also saves on a clutter of generating a bunch of extra migrations.

*** Doc Coverage

You can track progress of your documenting by noting how many tables have or have not been covered. Use the =coverage.zsh= script to offer a simple coverage report.

*** Round-Tripping (coming soon maybe)

If you already have comments on your tables, you can pull them into your ORG doc to still get the benefits of shared editing/viewing. So if some of your team happens to add comments inside a client on your production DB, round-tripping enables never losing data, and keeping your =dbcoc.org= as the SPOT. (This is maybe coming soon; probably not.)

*** Seeding an ORG doc file for first-time use

You can create a listing of all existing public tables as a starter ORG file: see =schema2org.zsh=. Once created, you can just start documenting! This is probably totally buggy; it's a tiny sed script working off a pg-dump.

This may be improved to populate with existing comment descriptions to enable “round-tripping”.

*** FAQs

Why use org instead of the more popular/common markdown?

ORG has definition lists which work great for column docs. For the limited syntax that is DBDoc, org and md are effectively the same (just use =*= for heading instead of =#=).

But [[https://github.com/MicahElliott/dbdoc/issues/2][I will implement Markdown]] if anyone feels they need it.

Do I need Emacs to work with Org files?

No! Emacs is not required to for any part of DBDoc. Most common editors have some proper way to work with Org. Even if yours doesn't, just edit in plain text mode.

How far should I go with documenting my tables?

Not super far. See recommendations above. I like to limit column docs to not more than a few sentences. A table doc can be a legthy paragraph (only one!). Your source code docstrings are probably a better place to get into the nitty gritty.

Why not just write the doc strings in SQL?

Then your editor would think you’re in SQL mode and wouldn’t do things like spell-checking or nice formatting. Plus, using ORG gives you a publishable HTML version of your docs.

Does this work for all databases?

It does work for many! It's been tested with PostgreSQL, and should work with others too, such as:

• [[https://www.cockroachlabs.com/docs/stable/comment-on.html][CockroachDB]]
• [[https://docs.oracle.com/cd/B19306_01/server.102/b14200/statements_4009.htm][Oracle]]
• [[https://www.ibm.com/support/producthub/db2/docs/content/SSEPGG_11.5.0/com.ibm.db2.luw.sql.ref.doc/doc/r0000901.html][IBM DB2]]
• [[https://docs.snowflake.com/en/sql-reference/sql/comment.html][Snowflake]]
• [[https://www.vertica.com/docs/9.2.x/HTML/Content/Authoring/SQLReferenceManual/Statements/COMMENT/COMMENTONTABLE.htm?tocpath=SQL%20Reference%20Manual%7CSQL%20Statements%7CCOMMENT%C2%A0ON%C2%A0Statements%7C_____9][Vertica]]

[[https://issues.apache.org/jira/browse/DERBY-7008][Apache Derby may get support]].

[[https://stackoverflow.com/questions/7426205/sqlite-adding-comments-to-tables-and-columns][I don't think SQLite supports =COMMENT=.]] And [[https://stackoverflow.com/questions/2162420/alter-mysql-table-to-add-comments-on-columns][MySQL makes it very difficult]] (and [[https://stackoverflow.com/questions/58665398/modifing-comment-into-spark-table-on-databricks][Spark]]) to the point that DBDoc won't attempt to make it work. [[https://feedback.azure.com/forums/307516-sql-data-warehouse/suggestions/16317988-table-extended-properties][SQL Server/Azure is a fail too]]. And [[https://community.cloudera.com/t5/Support-Questions/Is-there-way-to-add-comment-to-a-phoenix-table/td-p/165405][Ignite]].

How do I get this into Confluence without API access?

Your Confluence setup might only support creating a page from markdown (not org or html). So you can use pandoc to convert from org to md with: =pandoc -s docs/dbdoc.org -o temp.md= and then paste it into Confluence from its "plus" menu while editing a page: /Markup > Markdown > Paste > Insert/

Why can't I use just my SQL client to add descriptive comments?

Because it seems wrong. Which copy of your DB are you wanting to modify? Are you connecting your client to a production DB and making edits to prod data? This doesn't make sense to me and I don't understand why SQL clients support =COMMENT= editing. Developers, DBAs, QA, and others may not have prod access, and probably all need different non-prod DBs to have up-to-date documentation at their fingertips, and DBDoc enables putting that documentation into every instance.

** Similar Tools Comparison

*** dbdocs (same name but plural!)

[[https://dbdocs.io/][dbdocs]] (plural) is decsribed as: "A free & simple tool to create web-based database documentation using DSL code. Designed for developers. Integrate seamlessly with your development workflow." As a full DDL DSL, it is a much heavier commitment to incorporate. It also creates a rich website for your tables, whereas /DBDoc/ just creates a single webpage that can be synced with Confluence or published wherever you choose. dbdocs creates ERDs, but /DBDoc/ lets capable clients like DBeaver handle that for you.

*** Rails ActiveRecord

The [[https://github.com/rails/rails/pull/22911][ActiveRecord ORM]] has the ability to support comments as part of a schema definition and migration syntax. You may not need DBDoc if you're using AR. But if you want to publish your schema documentation, you should still use DBDoc!

*** Commercial Tools

There are many DB documentation tools in this realm. For any use cases I've encountered, they are overkill. But if you're interested in much more sophisticated kitchen sink tools that may work with other types of DBMSs, look into [[https://www.apexsql.com/sql-tools-doc.aspx][ApexSQL]], [[https://www.red-gate.com/products/sql-development/sql-doc/][Redgate]], and [[https://dataedo.com/][Dataedo]].

** Future Enhancements

• Support =COMMENT ON DATABASE= as top-level paragraph (but ignore myriad other types). Actually, this can't be done flexibly since it requires knowing the DB name.

• Identify fields/tables that are missing comments

Please submit an issue if you think of any enhancements or find bugs. I'm eager to improve this, but need your ideas!

** More Screenshots

Hover to see captions, just like in DB clients! There, you've been trained.

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