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

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.7.0, 1.8.0
• Component/s: documentmk, rdbmk
• Epic Link: RDB Support
• Assignee: Julian Reschke
• Reporter: Julian Reschke
• Created: 10/May/17 13:19
• Updated: 12/Jul/19 12:07
• Resolved: 17/May/17 14:43

Description

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

Issue Links

• is blocked by: OAK-6226 RDBDocumentStoreDB: missing @Override statements