Features of Postgres95

You will find the following topics below:

• Relationship to Postgres V4.2
• General Architecture
• API's
  • Query Language (SQL)
  • C API (libpq)
  • Tcl API (pgtcl)
  • Perl API (pg95perl)
  • Python API (PyGres95)
• Miscellaneous Packages
  • Wdb-p95 (a WWW gateway)
  • Japanese Kanji Code with Postgres95

• Relational. One of original research goals of the postgres project was to show that an essentially relational DBMS can be extended to handle complex objects, rules, and be highly extensible. Postgres95 includes features found in most full fledged relational DBMS's such as declarative queries in SQL, query optimization, concurrency control, transactions, and multi-user support.
• Highly Extensible. Postgres95 allows user-defined operators, types, functions, and access methods.
• Object-relational. Some have used the term "object-relational" to describe Postgres95 because it supports some object-oriented features such as inheritance.

Postgres95 retains a number of other interesting features from the original postgres research project. For more details, please see the many research papers published about Postgres.

• the postmaster is a supervisory daemon process. It manages the communication between frontend and backend processes, as well as allocating the shared buffer pool (in shared memory) and performing other initialization during start-up.

• the postgres backend database server process. This is the process that does the real work (ie. executes the queries). The postmaster starts a new backend process for each frontend connection. (The postgres backend always run on the server machine.)

• the frontend application (e.g. psql), possibly running on another machine (e.g. a client workstation), requests a connection to a postgres backend through the postmaster.

Query Language (SQL)

ABORT TRANSACTION, ALTER TABLE, BEGIN TRANSACTION, CHANGE ACL, CLOSE, COPY, CREATE AGGREGATE, CREATE DATABASE, CREATE FUNCTION, CREATE INDEX, CREATE OPERATOR, CREATE RULE, CREATE TABLE, CREATE TYPE, CREATE VERSION, CREATE VIEW, DECLARE, DELETE, DROP AGGREGATE, DROP DATABASE, DROP FUNCTION, DROP INDEX, DROP OPERATOR, DROP RULE, DROP TABLE, DROP TYPE, DROP VIEW, END TRANSACTION, EXTEND INDEX, FETCH, GRANT, INSERT, LOAD, PURGE, REVOKE, SELECT, UPDATE, VACUUM.

Expressions (eg. in SELECT) can be any arbitrary arithmetic, logical or functional expressions or aggrgates.

Click here for the POSTQUEL to SQL translation quick reference.

C API

Below is a simple example of the interface. (It creates a table foo in database mydb.)

    main()
    {
	  PGconn* conn;
	  conn = PQsetdb(NULL, NULL, NULL, NULL, "mydb");

          PQexec(conn, "create table foo (bar int4);");
    }

Tcl API

Below is a simple example of the interface. (It creates a table foo.)

    set conn [pg_connect $dbname -host $host -port $port]
    pq_exec $conn "create table foo (bar int4);"

Perl API

Below is a simple example of the interface. (It creates a table foo.)

    &PQexec ("create table foo (bar int4)");

Thanks to Edmund Mergl (mergl@nadia.s.bawue.de), a Perl5 interface, pg95perl5 is also available (pub/postgres95/pg95perl5-1.1.tar.gz).

Python API

PyGres95 is contributed by Pascal ANDRE (andre@zen.via.ecp.fr).

Wdb-p95

Doug Dunlop modified the code from the WDB package developed by Bo Frese Rasmussen to provide a gateway between Postgres95 and the WWW. It requires postgres95, perl4 and pgperl4 for postgres95. More info can be obtained here.

Japanese Kanji Code with Postgres95

Mr. Tatsuo Ishii(SRA) wrote an article about his library searching system with Postgres and HTML in the "Computer Today" magazine(May/1995) in Japan. A patch that lets you search strings with regular expresson in Japanese is available in "ftp://ftp.sra.co.jp/pub/cmd/postgres/".

(from Jun Kuwamura <juk@rccm.co.jp>)

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