Freebase

Features

• ACID Transactions (Durable only if using persistent log implementations)
• Write Ahead Logging (WAL) - Recovery (checkpoint almost complete)
• COMMIT, ROLLBACK, SAVEPOINT
• Statement level atomicity - Failed statements revert system to prior state
• Multi View Concurrency (MVC) - readers don't block writers (ala Oracle, Postgres, InnoDB)
• Row level locks - lock information stored with row data, thus no escalation ever needed
• Table Locks - row share, row exclusive, share, share row exclusive, and exclusive modes all supported
• Unique Keys
• Isolation Levels - read uncommitted, read committed, repeatable read, and serializable
• Deadlock Detection
• Partial SELECT implementation - no outer joins, subselects nor set operations (union [all], intersect)
• INSERT, UPDATE, DELETE
• Sequences - nextval and currval
• Partial JDBC Driver - batches and prepared statements implemented, but no meta data yet.
• SQL Client available - explain plan
• Connection management and cleanup
• Database Metadata stored in catalog tables

Here is the list of features that the system doesn't do (yet?). This is is here to give you an idea of what I am thinking about.

Basics

• poor data validation currently
  
• rough edges on commands
• no securitity
• no legitimate BLOB support
• no Unicode

Queries

• current index utilization offers poor selectivity (easy to improve)
• no select for update (plan in place, implementation deferred)
• no subselects (in where clause, from clause or anywhere)
• no outer joins (SQL 92 join semmatics not implemented yet)
• no views
• prepared statements are simulated (ie, no true statement cache)
• parallel query

Core Capabilities

• no Stored Procedures
• no triggers
• temp tables
• no foreign keys

Enterprise

• memory only db very limiting
• replication (hot or warm) - warm using log replication and fast recovery straightforward, hot more difficult
• clustering
• hot backup (not need yet)

And so on...

Two of the core limitations of the current implemetation are in the following areas:

1. A world class query engine
2. A highly scalable block based disk persistence

License

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Build/Run Instructions

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