Java Glossary : PostgreSQL

Last updated 2004-06-28 by Roedy Green ©1996-2004 Canadian Mind Products

Java definitions: 0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

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PostgreSOL

A free SQL database. It has a number of advantages over MySQL.

• PostGres is a mature product with its roots in Berkeley.
• PostGres has many data types.
• You can add your own data tapes by defining them with a little C code.
• You can write triggers in Oracle stored procedure language PL/SQL or in other languages such as Java.
• PostGres is highly compatible with Oracle. It handles triggers the same way.
• PostGres does not crash under heavy loads.
• PostGres has remote SSL access.
• PostGres has PGADMIN3 for a graphical way of administration from a PC.
• PostGres allows inheritance in the SQL definitions. E.g. a capitals row definition can be derived from a cities row definition.
• PostGres uses multiversion concurrency control, rather than locks. Each transaction sees a snapshot of the database at a logical instant in time. Reading does not block writing and vice versa.
• MySQL 4.1 alpha (preliminary version) now too has subselects. For many years it did not where PostgreSQL did.
• MySQL does not support transactions. You can't back out after a few database changes. I don't know what you can do in PostgreSQL.

MySQL's advantages are:

• MySQL is easier to set up.
• MySQL support is more widespread on ISP webservers.
• There more books and tutorials on MySQL.

Supported Types

Name	Aliases	Description
bigint	int8	signed eight-byte integer
bigserial	serial8	autoincrementing eight-byte integer
bit		fixed-length bit string
bit varying(n)	varbit(n)	variable-length bit string
boolean	bool	logical Boolean (true/false)
box		rectangular box in the plane
bytea		binary data
character varying(n)	varchar(n)	variable-length character string
character(n)	char(n)	fixed-length character string
cidr		IPv4 or IPv6 network address
circle		circle in the plane
date		calendar date (year, month, day)
double precision	float8	double precision floating-point number
inet		IPv4 or IPv6 host address
integer	int, int4	signed four-byte integer
interval(p)		time span
line		infinite line in the plane (not fully implemented)
lseg		line segment in the plane
macaddr		MAC address
money		currency amount
numeric [ (p, s) ]	decimal [ (p, s) ]	exact numeric with selectable precision
path		open and closed geometric path in the plane
point		geometric point in the plane
polygon		closed geometric path in the plane
real	float4	single precision floating-point number
smallint	int2	signed two-byte integer
serial	serial4	autoincrementing four-byte integer
text		variable-length character string
time [ (p) ] [ without time zone ]		time of day
time [ (p) ] with time zone	timetz	time of day, including time zone
timestamp [ (p) ] without time zone	timestamp	date and time
timestamp [ (p) ] [ with time zone ]	timestamptz	date and time, including time zone

Database Journal comparsion ¤ DevX comparison ¤ MySQL gotchas ¤ SQL

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