[jira] [Created] (OAK-6207) RDBDocumentStore: allow schema evolution part 2: record schema version when updating/inserting rows

["Julian Reschke (JIRA)" <ji...@apache.org>]

Julian Reschke created OAK-6207:
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             Summary: RDBDocumentStore: allow schema evolution part 2: record schema version when updating/inserting rows
                 Key: OAK-6207
                 URL: https://issues.apache.org/jira/browse/OAK-6207
             Project: Jackrabbit Oak
          Issue Type: Technical task
            Reporter: Julian Reschke


Currently, new/extra columns get reported on startup but then are ignored. This allows evolving the schema without immediately breaking existing installs. However, we won't know whether a value in a new column was put there deliberately or just wasn't updated properly by old code.

Idea:

- add a new "VERSION" column
- when inserting/updating rows, record the DB schema version understood by the code doing the update

Advantages:

- allows relatively easy check what versions of code are writing to the DB
- inexpensive
- helps finding rows that need a migration step

Disadvantage:

- the row itself will be unreliably until all instances connecting to the DB maintain it



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