Ingres

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Ingres is an open-source relational database management system (DBMS) designed for large-scale commercial and government applications. Actian Corporation currently oversees the development of the database while providing certified binaries and support. The latest version is Ingres 11, which is also known commercially as the Actian X Hybrid Database. Currently, its strong at OLTP while supporting analytic features.

History

When two University of California, Berkeley professors, Michael Stonebraker and Eugene Wong, read the papers about System R at IBM in 1973, they became interested in applying the concepts in those papers on a research project of their own, and thus Ingres was born. From its birth to 1985, Ingres was a research project at the University.

In the mid-1980s, Ingres competed against Oracle in the then-emerging relational DBMS market. These two systems were considered to have comparable functionalities and performance, and were the market leaders. However, from then on, Ingres slowly lost market share to Oracle presumably due to the latter's more aggressive marketing, and more importantly, the recognition of SQL as the go-to query language, which Ingres did not use at the time. It used a query language called Quel and the transition to SQL took three years. Nevertheless, Ingres reincarnated as the underlying source code of many commercial databases, one of the most well-known being Relational Technology Inc, founded by the very same two professors who started Ingres as a research project. The company was later renamed Ingres Corporation in the late 1980s, and continued to provide commercial database products with Ingres lying underneath. Although Ingres never achieved the same market prominence as its once head-to-head contender Oracle, it endured over the years and was the inspiration for many other popular database management systems, such as Postgres.

In 2011, Ingres Corporation was renamed Actian Corporation and has continued its support on the classic DBMS since then. It is currently branded as the Actian X Hybrid Database.

Compression of tables only work on character and text columns. Trailing nulls and blanks are compressed. Non-nullable types such as Integer, floating point, and date are not compressed.

Joins

Nested Loop Join Hash Join Sort-Merge Join Index Nested Loop Join

Query Interface

SQL Command-line / Shell QUEL

Indexes

B+Tree Hash Table R-Tree

Storage Architecture

Disk-oriented

Although it is currently branded as the "Actian Hybrid", the "Hybrid" refers to its capability of performing both OLTP and OLAP tasks by employing a hybrid storage model (i.e. both row and column), not that it has a hybrid storage architecture. It is still disk oriented as it was from day-one.

Storage Organization

Heaps Indexed Sequential Access Method (ISAM)

Foreign Keys

Supported

Query Compilation

Stored Procedure Compilation

Concurrency Control

Multi-version Concurrency Control (MVCC) Deterministic Concurrency Control Two-Phase Locking (Deadlock Detection)

Ingres uses the terms "logical lock" and "physical lock" to refer to transaction locks and latches, respectively. It supports multiversion concurrency control (MVCC). Its available lock levels are, from most to least granular, are Row, MVCC, Page, Table, Database. It supports deadlock detection and aborts one of the transactions that are deadlocked.

Checkpoints

Consistent Blocking

Ingres supports two types of checkpointing: online and offline. Offline checkpointing requires all users to disconnect from the database. It acquires a global lock on the entire database and performs backup on all the data. Online checkpointing does not require users to disconnect and is the default checkpointing scheme, although it is still blocking. Users cannot proceed until the Ingres creates a consistent point of the database, although this takes much less time than offline checkpointing. The DBMS records all changes in the database but does not support operations such as drop or create during the checkpoint.