Database schemas and migrations

RustBox keeps SQL, blob storage and search as independent concerns.

database_backend = sqlite | mysql | pgsql
session_backend  = database | redis
storage.backend  = filesystem | s3
search.backend   = disabled | local_tantivy | opensearch

Layout

migrations/
├── sqlite/schema.sql
├── mysql/schema.sql
└── pgsql/schema.sql

Each schema.sql is the complete V050 schema for fresh installations. Migrations V047-V049 have been consolidated into the V049 compatibility baseline and their standalone files are intentionally removed. V050 remains the single runtime migration. Because RustBox 0.2.15 has not been released yet, V050 includes mail_preferences.compact_wide_rows, identities.signature_insert_mode, display_preferences.adaptive_email_colors and mail_preferences.message_loading_mode.

mail_preferences.message_loading_mode defaults to pagination; messages_per_page defaults to 300. Supported modes are pagination, progressive and all.

Databases older than V049 are no longer migrated directly by this build. Upgrade them to schema V049 first; this build then applies V050. V051 is the next migration number after this snapshot.

Account data is isolated inside the selected physical database with a deterministic, collision-checked table prefix derived from the account hash. The {{p}} marker in tenant SQL is replaced by RustBox at provisioning time. Sessions are global and therefore are not prefixed.

Runtime migrations

V050 is the only runtime migration in this unreleased snapshot. Future schema-changing releases must add the same logical migration for SQLite, MySQL and PostgreSQL and register it in src/db/pool.rs.

Redis and Redis Sentinel do not use SQL migrations.

Engine notes

SQLite uses data_dir/rustbox.sqlite by default; database_url may point to another persistent SQLite file.
MySQL requires database_url and targets MySQL 8.0.13 or newer.
PostgreSQL requires database_url.
MySQL/PostgreSQL are full application backends, not session-only databases.
The SQL engine does not choose blob/search storage. PostgreSQL/MySQL may still use local filesystem/Tantivy in single-node mode.
Cluster mode requires a shared MySQL/PostgreSQL database plus cluster-safe blob/search choices; local data_dir is not inherently required.