Foreign Keys

Supported

CUBRID supports foreign key constraint, i.e. a set of columns that references the primary key in other tables. Users can also specify what action is triggered by update or delete of the primary key referenced. Options include:

• CASCADE: deletes the foreign key when the associated the primary key got deleted.
• SET NULL: updates the value of the foreign key to NULL when the corresponding record is deleted or updated.
• RESTRICT: guarantees the primary key associated with this foreign key remains constant. Any transaction attempting to update or delete this primary key will be roll back.

Stored Procedures

Supported

CUBRID supports stored functions and procedures (via java) which enables complicated logic infeasiable otherwise through SQL. This functionality is turned off by default.

Isolation Levels

Snapshot Isolation

CUBRID supports true snapshot isolation under the Multiversion Concurrency Control (MVCC) protocol. CUBRID provides 3 isolation levels: Serializable, Repeatable read, and Read committed, where Read commited is the default.

Joins

Nested Loop Join Sort-Merge Join Index Nested Loop Join

CUBRID allows user to set optimization levels and get current query plan. Specifically for join methods, it supports nested loop join, sort merge join (turned off by default), and index nested loop join.

Concurrency Control

Multi-version Concurrency Control (MVCC)

Since v10.0, CUBRID moved from two phase locking protocol (2PL) to a Multiversion Concurrency Control (MVCC) protocol. The gain is mostly non-blocking reads for read intensive applications, typical in real-world use cases. This also grants point-in-time consistent view of the database, and reduction of performance costs compared to other concurrency protocols.

Storage Organization

Heaps

Logging

Physical Logging

CUBRID allows user to configure the frequency of logging and the life span of log archives. For example, user can set the size of log buffer cached in memory, and the maximum number of archive log files stored in disk. Archiving runs in the background by default.

Query Compilation

Not Supported Code Generation

CUBRID in general does not support query compilation. However, its PHP API (and PHP API only) provides a method which pre-compiles the SQL statement accepted, which can be used for re-executing the statement or effectively processing Long Data.

Data Model

Object-Relational

CUBRID is an object-relational database management system, that is, it is essentially similar to relational database, but also provides an object oriented database elements relations.

System Architecture

Shared-Nothing

CUBRID allows one master process for each host. It offers CUBRID High Availability (HA) which supports uninterrupted services under a hardware, software or network failure. It ensures database synchronization among multiple servers, and is implemented under shared-nothing architecture. Synchronization between an active server and a standby server is achieved through transaction log multiplexing and reflection.

Query Interface

Custom API SQL Stored Procedures Command-line / Shell

CUBRID supports a wide range of SQL syntaxs. It also provides APIs in various languages with corresponding driver, e.g. JDBC Driver, PHP Driver, CCI Driver (C-based application), Perl Driver, Python Driver, etc. Additionally, user can also interact with CUBRID via its GUI-based program called CUBRID Manager.

Checkpoints

Non-Blocking

CUBRID allows user to configure checkpoint through two options: 1. Configure checkpoint trigger by log page size. Checkpoint will be triggered every time the transaction log size has reaches the set value. 2. Configure checkpoint tigger by time interval. Checkpoint runs in a periodical fashion. The default is 6 minutes. 3. Configure a slow data flush from the buffer to disk.

Storage Model

Custom

As an object-relational database, CUBRID stores records as objects with an unique Object Identifier (OID). Insertions, deletions and modifications of records on pages are managed by the Slotted Page Manager, and large object which does not fit in a single page is placed on overflow pages managed by the Overflow File Manager.

Views

Virtual Views

CUBRID supports creation of views via statement CREATE VIEW. The virtual tables does not exist physically, but can be updatable if it satisfies some criteria.

Storage Architecture

Disk-oriented

CUBRID is a disk-oriented database, memory is used for caching purposes. User can configure several disk-related parameters for database volumes and files, such as database volumn size and log volume size (both default to 512M), or the percentage of disk space allocated in a heap page for updates.

Indexes

B+Tree

CUBRID uses B-trees for indexes files. It supports the following types of indexes:

• Indexes and unique indexes
• Filtered index: used for creating indexes on a subset of rows in the table if certain criteria is met. The criteria is set by the user when creating this filtered index.
• Function-based index: used for indexing rows based on a function accepting values in table rows as arguments. It is typically used for indexes created from complex conditions or calculations.