schema-swapping

name	schema-swapping
description	Transaction model using __odd/__even schema slots. Use when working on init_stage, commit_stage, Schema, Stage, or transaction handling.

Schema Swapping

Transaction model: each stage has two transaction slots (__odd/__even). During init_stage, the inactive slot is prepared. On commit_stage, views in the main schema are redirected.

Key classes

• Schema (in container/) — wraps name + prefix + suffix, .get() returns the full name
• Stage — has .name (bare), .current_name (set during execution), .transaction_name
• _commit_stage_read_views() calls on_clear_schema() and on_read_view_alias() callbacks

Flow

1. init_stage(): determines old/new transaction names, syncs metadata, creates the new transaction schema
2. Tasks run, materializing into the transaction schema
3. commit_stage(): swaps the main schema views to point at the new transaction schema
4. _committed_unchanged(): if stage is fully cache-valid, discards the transaction schema instead