https://github.com/solidsnack/macaroon

Postgres introspection and macros
https://github.com/solidsnack/macaroon

Last synced: about 1 month ago
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Postgres introspection and macros

• Host: GitHub
• URL: https://github.com/solidsnack/macaroon
• Owner: solidsnack
• Created: 2015-06-28T06:33:01.000Z (over 9 years ago)
• Default Branch: master
• Last Pushed: 2023-01-01T06:41:48.000Z (almost 2 years ago)
• Last Synced: 2023-04-09T12:18:36.930Z (over 1 year ago)
• Language: PLpgSQL
• Size: 23.4 KB
• Stars: 16
• Watchers: 2
• Forks: 3
• Open Issues: 1
• Metadata Files:
  • Readme: README.md
  • Audit: audit.sql

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README

        

Many tricky table configurations -- for example, logged tables and partitioned

tables -- would seem to be amenable to mechanical derivation. The SQL standard

provides for fairly rich introspection capabilities -- on par with any object

oriented language -- so it stands to reason that we should be able to use

metaprogramming to derive advanced table configurations mechanically.

The `meta` schema in `meta.sql` should be loaded before loading the others. To

load all the schemas together, run `\i macaroon.psql` at the `psql` prompt.

Creating Tables for Auditing & Versioning

-------------------------------------------

Imagine that your application has tables in the `app` namespace; and you'd like

to log past row versions and metadata about changes to the `state` and `events`

schemas, respectively. You can idempotently configure both audit and version

stracking by `SELECT`ing tables in the `app` namespace that are not already

tracked and passing them to the setup functions:

```sql

SELECT tab,

       temporal.temporal(tab, 'state'),

       audit.audit(tab, 'events')

  FROM pg_tables,

       LATERAL (SELECT (schemaname||'.'||tablename)::regclass AS tab)

            AS casted_to_regclass

 WHERE schemaname = 'app'

   AND tab NOT IN (SELECT logged FROM temporal.logged

                    UNION

                   SELECT audited FROM audit.audited);

      tab      │    temporal     │      audit

───────────────┼─────────────────┼──────────────────

 app.user_info │ state.user_info │ events.user_info

 app.telephone │ state.telephone │ events.telephone

 app.cpu       │ state.cpu       │ events.cpu

 ...           │ ...             │ ...

```

Using The Auditing & Versioning Tables

--------------------------------------

The audit and temporal tables for each table that is tracked can be joined on

the `txid` column to see all the actions that took place during a particular

transaction.

A Note About Migrations

-----------------------

The audit tables are indifferent to migrations -- they do not store any row

data.

The temporal tables store `JSONB`, so they're also indifferent to migrations.