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Comment by Mister_Snuggles | Hacker News Reader

This could be enforced in the schema via triggers and/or security permissions. Cooperation from the client is not required.

EDIT: Oracle has append-only tables, and can also use "blockchain" to verify integrity. See the IMMUTABLE option on CREATE TABLE[0]. PostgreSQL doesn't appear to have append-only tables, so using security and/or triggers seems to be the only option there.

[0] https://docs.oracle.com/en/database/oracle/oracle-database/2...

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More to the point Oracle has flashback queries:

    SELECT ... AS OF <timestamp or logical clock time>

So you can query the database as of any point in the past, making manual work to implement the same feature with custom columns redundant.

Oracle can also show you a record of transactions made and what SQL to run to undo them, including dependency tracking between transactions.

This sounds like proprietary syntax for SQL 2011 temporal queries. Apparently supported by eg MS SQL server and MariaDB.

You're correct, I overlooked triggers. Though that may be a bridge too far for some folks, triggers are only really comfortable for folks who are deep on RDBMSes. For lots of app developers the ORM is the limit of the world.

ORMs could offer a unique advantage by allowing the user to describe an append-only table and generating the required triggers (or the appropriate CREATE TABLE options). They'd also be able to include helpers to make working with the table easier - like defaulting to selecting current rows only, or an easy way to specify that you want rows as-of a certain point in time.

I'm not sure if any ORMs actually support this though.

I suspect there have been a great many examples and attempts at the ORM level - this one with "bi-temporal chaining" springs to mind: https://github.com/goldmansachs/reladomo

And without the ORM layer there's this extension for Postgres: https://github.com/hettie-d/pg_bitemporal

My "ORM" supports event sourcing, or at least easily plugging it in at the model level.

https://github.com/codr7/hostr/blob/532295b40dcad6c54082e1d3...

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