Code Metaphor

psql에서 \dT+라고 치면 아래 표가 나온다.

Schema	Name	Internal name	Size	Description
pg_catalog	"any"	any	4
pg_catalog	"char"	char	1	single character
pg_catalog	abstime	abstime	4	absolute, limited-range date and time (Unix system time)
pg_catalog	aclitem	aclitem	12	access control list
pg_catalog	anyarray	anyarray	var
pg_catalog	anyelement	anyelement	4
pg_catalog	anyenum	anyenum	4
pg_catalog	anynonarray	anynonarray	4
pg_catalog	bigint	int8	8	~18 digit integer, 8-byte storage
pg_catalog	bit	bit	var	fixed-length bit string
pg_catalog	bit varying	varbit	var	variable-length bit string
pg_catalog	boolean	bool	1	boolean, true/false
pg_catalog	box	box	32	geometric box (lower left,upper right)
pg_catalog	bytea	bytea	var	variable-length string, binary values escaped
pg_catalog	character	bpchar	var	char(length), blank-padded string, fixed storage length
pg_catalog	character varying	varchar	var	varchar(length), non-blank-padded string, variable storage length
pg_catalog	cid	cid	4	command identifier type, sequence in transaction id
pg_catalog	cidr	cidr	var	network IP address/netmask, network address
pg_catalog	circle	circle	24	geometric circle (center,radius)
pg_catalog	cstring	cstring	var
pg_catalog	date	date	4	ANSI SQL date
pg_catalog	double precision	float8	8	double-precision floating point number, 8-byte storage
pg_catalog	gtsvector	gtsvector	var	GiST index internal text representation for text search
pg_catalog	inet	inet	var	IP address/netmask, host address, netmask optional
pg_catalog	int2vector	int2vector	var	array of int2, used in system tables
pg_catalog	integer	int4	4	-2 billion to 2 billion integer, 4-byte storage
pg_catalog	internal	internal	4
pg_catalog	interval	interval	16	@ <number> <units>, time interval
pg_catalog	language_handler	language_handler	4
pg_catalog	line	line	32	geometric line (not implemented)
pg_catalog	lseg	lseg	32	geometric line segment (pt1,pt2)
pg_catalog	macaddr	macaddr	6	XX:XX:XX:XX:XX:XX, MAC address
pg_catalog	money	money	8	monetary amounts, $d,ddd.cc
pg_catalog	name	name	64	63-character type for storing system identifiers
pg_catalog	numeric	numeric	var	numeric(precision, decimal), arbitrary precision number
pg_catalog	oid	oid	4	object identifier(oid), maximum 4 billion
pg_catalog	oidvector	oidvector	var	array of oids, used in system tables
pg_catalog	opaque	opaque	4
pg_catalog	path	path	var	geometric path (pt1,...)
pg_catalog	point	point	16	geometric point (x, y)
pg_catalog	polygon	polygon	var	geometric polygon (pt1,...)
pg_catalog	real	float4	4	single-precision floating point number, 4-byte storage
pg_catalog	record	record	var
pg_catalog	refcursor	refcursor	var	reference cursor (portal name)
pg_catalog	regclass	regclass	4	registered class
pg_catalog	regconfig	regconfig	4	registered text search configuration
pg_catalog	regdictionary	regdictionary	4	registered text search dictionary
pg_catalog	regoper	regoper	4	registered operator
pg_catalog	regoperator	regoperator	4	registered operator (with args)
pg_catalog	regproc	regproc	4	registered procedure
pg_catalog	regprocedure	regprocedure	4	registered procedure (with args)
pg_catalog	regtype	regtype	4	registered type
pg_catalog	reltime	reltime	4	relative, limited-range time interval (Unix delta time)
pg_catalog	smallint	int2	2	-32 thousand to 32 thousand, 2-byte storage
pg_catalog	smgr	smgr	2	storage manager
pg_catalog	text	text	var	variable-length string, no limit specified
pg_catalog	tid	tid	6	(block, offset), physical location of tuple
pg_catalog	time with time zone	timetz	12	hh:mm:ss, ANSI SQL time
pg_catalog	time without time zone	time	8	hh:mm:ss, ANSI SQL time
pg_catalog	timestamp with time zone	timestamptz	8	date and time with time zone
pg_catalog	timestamp without time zone	timestamp	8	date and time
pg_catalog	tinterval	tinterval	12	(abstime,abstime), time interval
pg_catalog	trigger	trigger	4
pg_catalog	tsquery	tsquery	var	query representation for text search
pg_catalog	tsvector	tsvector	var	text representation for text search
pg_catalog	txid_snapshot	txid_snapshot	var	txid snapshot
pg_catalog	unknown	unknown	var
pg_catalog	uuid	uuid	16	UUID datatype
pg_catalog	void	void	4
pg_catalog	xid	xid	4	transaction id
pg_catalog	xml	xml	var	XML content

네트워크 주소를 저장하는 용도인 cidr, inet, macaddr 같은 것도 있고, box, circle, line, path, point, polygon 같은 기하학적 값들을 위한 자료형도 존재한다.

눈여겨 볼 것은, regclass나 regtype 같은 고차 자료형(higher-order types)—자료형을 담는 자료형, Ruby의 Class 객체나 Python의 type 객체 같은 것들—도 존재한다는 사실. regoper, regproc 같은 자료형을 보면 알 수 있겠지만, 연산자나 프로시져를 값으로 사용할 수 있기도 하다. regoperator, regprocedure 자료형은 부분 적용(partial application)된 연산자, 프로시져를 담는다.

이 얼마나 강력하고 유연한 ORDBMS인가.