PostgreSQL System Catalog

효율적인 데이터베이스 관리를 위해 내부적인 catalog를 사용한다.

catalog는 다른 RDBMS에서 data dictionary로 불리기도 한다. 

system catalogs list

Catalog Name	Purpose
ag_graph	graph information
ag_label	label information
pg_aggregate	aggregate functions
pg_am	index access methods
pg_amop	access method operators
pg_amproc	access method support procedures
pg_attrdef	column default values
pg_attribute	table columns (“attributes”)
pg_auth_members	authorization identifier membership relationships
pg_authid	authorization identifiers (roles)
pg_cast	casts (data type conversions)
pg_class	tables, indexes, sequences, views (“relations”)
pg_collation	collations (locale information)
pg_constraint	check constraints, unique constraints, primary key constraints, foreign key constraints
pg_conversion	encoding conversion information
pg_database	databases within this database cluster
pg_db_role_setting	per-role and per-database settings
pg_default_acl	default privileges for object types
pg_depend	dependencies between database objects
pg_description	descriptions or comments on database objects
pg_enum	enum label and value definitions
pg_event_trigger	event triggers
pg_extension	installed extensions
pg_foreign_data_wrapper	foreign-data wrapper definitions
pg_foreign_server	foreign server definitions
pg_foreign_table	additional foreign table information
pg_index	additional index information
pg_inherits	table inheritance hierarchy
pg_init_privs	object initial privileges
pg_language	languages for writing functions
pg_largeobject	data pages for large objects
pg_largeobject_metadata	metadata for large objects
pg_namespace	schemas
pg_opclass	access method operator classes
pg_operator	operators
pg_opfamily	access method operator families
pg_pltemplate	template data for procedural languages
pg_policy	row-security policies
pg_proc	functions and procedures
pg_range	information about range types
pg_replication_origin	registered replication origins
pg_rewrite	query rewrite rules
pg_seclabel	security labels on database objects
pg_shdepend	dependencies on shared objects
pg_shdescription	comments on shared objects
pg_shseclabel	security labels on shared database objects
pg_statistic	planner statistics
pg_tablespace	tablespaces within this database cluster
pg_transform	transforms (data type to procedural language conversions)
pg_trigger	triggers
pg_ts_config	text search configurations
pg_ts_config_map	text search configurations' token mappings
pg_ts_dict	text search dictionaries
pg_ts_parser	text search parsers
pg_ts_template	text search templates
pg_type	data types
pg_user_mapping	mappings of users to foreign servers

system views list

View Name	Purpose
pg_available_extensions	available extensions
pg_available_extension_versions	available versions of extensions
pg_config	compile-time configuration parameters
pg_cursors	open cursors
pg_file_settings	summary of configuration file contents
pg_group	groups of database users
pg_hba_file_rules	summary of client authentication configuration file contents
pg_indexes	indexes
pg_locks	locks currently held or awaited
pg_matviews	materialized views
pg_policies	policies
pg_prepared_statements	prepared statements
pg_prepared_xacts	prepared transactions
pg_publication_tables	publications and their associated tables
pg_replication_origin_status	information about replication origins, including replication progress
pg_replication_slots	replication slot information
pg_roles	database roles
pg_rules	rules
pg_seclabels	security labels
pg_sequences	sequences
pg_settings	parameter settings
pg_shadow	database users
pg_stats	planner statistics
pg_tables	tables
pg_timezone_abbrevs	time zone abbreviations
pg_timezone_names	time zone names
pg_user	database users
pg_user_mappings	user mappings
pg_views	views

 

다음은 주로 사용되는 system catalog 및 view에 대한 설명이다.

 

▶ System Catalogs (시스템 카탈로그)

• pg_class (\dS)

  Table, Index, Sequence, View 에 대한 종합적인 정보를 담고 있다. 

  Name	Type	References	Description
  relname	name		Name of the table, index, view, etc.
  relowner	oid	pg_authid.oid	Owner of the relation
  relnatts	int2		Number of user columns in the relation (system columns not counted). There must be this many corresponding entries in pg_attribute. See also pg_attribute.attnum.

• pg_constraint

  constraint에 대한 정보를 담고 있다.

  Name	Type	References	Description
  conname	name		Constraint name (not necessarily unique!)
  contype	char		c = check constraint, f = foreign key constraint, p = primary key constraint, u = unique constraint, t = constraint trigger, x = exclusion constraint

• pg_database (\l)

  해당 클러스터에 속한 database 정보를 담고 있다.

  Name	Type	References	Description
  datname	name		Database name
  datdba	oid	pg_authid.oid	Owner of the database, usually the user who created it
  encoding	int4		Character encoding for this database (pg_encoding_to_char() can translate this number to the encoding name)
  datcollate	name		LC_COLLATE for this database
  datctype	name		LC_CTYPE for this database
  datacl	aclitem[]		Access privileges; see GRANT and REVOKE for details

• pg_extension (\dx)

  해당 클러스터에 설치된 extension에 대한 정보를 담고 있다.

  Name	Type	References	Description
  extname	name		Name of the extension
  extowner	oid	pg_authid.oid	Owner of the extension
  extversion	text		Version name for the extension

• pg_namespace (\du) 

   schema 정보를 담고 있다.

  Name	Type	References	Description
  oid	oid		Row identifier (hidden attribute; must be explicitly selected)
  nspname	name		Name of the namespace
  nspowner	oid	pg_authid.oid	Owner of the namespace
  nspacl	aclitem[]		Access privileges; see GRANT and REVOKE for details

• pg_tablespace (\db)

  해당 클러스터에 속한 tablespace에 대한 정보를 담고 있다.

  Name	Type	References	Description
  spcname	name		Tablespace name
  spcowner	oid	pg_authid.oid	Owner of the tablespace, usually the user who created it

Name

▶ System Views (시스템 뷰)

• pg_available_extensions 

  사용 가능한 extension에 대한 정보를 담고 있다.

  Name	Type	Description
  name	name	Extension name
  default_version	text	Name of default version, or NULL if none is specified
  installed_version	text	Currently installed version of the extension, or NULL if not installed
  comment	text	Comment string from the extension's control file

• pg_file_settings

  config file에 설정된 내용에 대한 정보를 담고 있다.

  Name	Type	Description
  sourcefile	text	Full path name of the configuration file
  sourceline	integer	Line number within the configuration file where the entry appears
  seqno	integer	Order in which the entries are processed (1..n)
  name	text	Configuration parameter name
  setting	text	Value to be assigned to the parameter
  applied	boolean	True if the value can be applied successfully
  error	text	If not null, an error message indicating why this entry could not be applied

• pg_group

  데이터베이스 사용자 그룹에 대한 정보를 담고 있다.

  Name	Type	References	Description
  groname	name	pg_authid.rolname	Name of the group
  grosysid	oid	pg_authid.oid	ID of this group
  grolist	oid[]	pg_authid.oid	An array containing the IDs of the roles in this group

• pg_indexes 

  인덱스 정보를 담고 있다.

  Name	Type	References	Description
  schemaname	name	pg_namespace.nspname	Name of schema containing table and index
  tablename	name	pg_class.relname	Name of table the index is for
  indexname	name	pg_class.relname	Name of index
  tablespace	name	pg_tablespace.spcname	Name of tablespace containing index (null if default for database)
  indexdef	text		Index definition (a reconstructed CREATE INDEX command)

• pg_roles

  Database role에 대한 정보를 담고 있다.

  Name	Type	References	Description
  rolname	name		Role name
  rolsuper	bool		Role has superuser privileges
  rolinherit	bool		Role automatically inherits privileges of roles it is a member of
  rolcreaterole	bool		Role can create more roles
  rolcreatedb	bool		Role can create databases
  rolcanlogin	bool		Role can log in. That is, this role can be given as the initial session authorization identifier
  rolreplication	bool		Role is a replication role. A replication role can initiate replication connections and create and drop replication slots.
  rolconnlimit	int4		For roles that can log in, this sets maximum number of concurrent connections this role can make. -1 means no limit.
  rolpassword	text		Not the password (always reads as ********)
  rolbypassrls	bool		Role bypasses every row level security policy
  oid	oid	pg_authid.oid	ID of role

• pg_settings 

  config parameter에 대한 정보를 담고 있다.

  Name	Type	Description
  name	text	Run-time configuration parameter name
  setting	text	Current value of the parameter
  unit	text	Implicit unit of the parameter
  boot_val	text	Parameter value assumed at server startup if the parameter is not otherwise set
  reset_val	text	Value that RESET would reset the parameter to in the current session

• pg_shadow

  데이터베이스 사용자에 대한 정보를 담고 있다.

  Name	Type	References	Description
  usename	name	pg_authid.rolname	User name
  usesysid	oid	pg_authid.oid	ID of this user
  usecreatedb	bool		User can create databases
  usesuper	bool		User is a superuser
  userepl	bool		User can initiate streaming replication and put the system in and out of backup mode.
  usebypassrls	bool		User bypasses every row level security policy
  passwd	text		Password (possibly encrypted); null if none. See pg_authid for details of how encrypted passwords are stored.

• pg_stats

  planner 통계정보를 담고 있다.

  Name	Type	References	Description
  schemaname	name	pg_namespace.nspname	Name of schema containing table
  tablename	name	pg_class.relname	Name of table
  attname	name	pg_attribute.attname	Name of the column described by this row
  inherited	bool		If true, this row includes inheritance child columns, not just the values in the specified table
  null_frac	real		Fraction of column entries that are null
  avg_width	integer		Average width in bytes of column's entries
  n_distinct	real		If greater than zero, the estimated number of distinct values in the column. If less than zero, the negative of the number of distinct values divided by the number of rows. (The negated form is used when ANALYZE believes that the number of distinct values is likely to increase as the table grows; the positive form is used when the column seems to have a fixed number of possible values.) For example, -1 indicates a unique column in which the number of distinct values is the same as the number of rows.
  most_common_vals	anyarray		A list of the most common values in the column. (Null if no values seem to be more common than any others.)
  most_common_freqs	real[]		A list of the frequencies of the most common values, i.e., number of occurrences of each divided by total number of rows. (Null when most_common_vals is.)
  histogram_bounds	anyarray		A list of values that divide the column's values into groups of approximately equal population. The values in most_common_vals, if present, are omitted from this histogram calculation. (This column is null if the column data type does not have a < operator or if the most_common_vals list accounts for the entire population.)
  correlation	real		Statistical correlation between physical row ordering and logical ordering of the column values. This ranges from -1 to +1. When the value is near -1 or +1, an index scan on the column will be estimated to be cheaper than when it is near zero, due to reduction of random access to the disk. (This column is null if the column data type does not have a < operator.)
  most_common_elems	anyarray		A list of non-null element values most often appearing within values of the column. (Null for scalar types.)
  most_common_elem_freqs	real[]		A list of the frequencies of the most common element values, i.e., the fraction of rows containing at least one instance of the given value. Two or three additional values follow the per-element frequencies; these are the minimum and maximum of the preceding per-element frequencies, and optionally the frequency of null elements. (Null when most_common_elems is.)
  elem_count_histogram	real[]		A histogram of the counts of distinct non-null element values within the values of the column, followed by the average number of distinct non-null elements. (Null for scalar types.)

• pg_tables

  Table에 대한 정보를 담고 있다.

  Name	Type	References	Description
  schemaname	name	pg_namespace.nspname	Name of schema containing table
  tablename	name	pg_class.relname	Name of table
  tableowner	name	pg_authid.rolname	Name of table's owner
  tablespace	name	pg_tablespace.spcname	Name of tablespace containing table (null if default for database)
  hasindexes	boolean	pg_class.relhasindex	True if table has (or recently had) any indexes
  hasrules	boolean	pg_class.relhasrules	True if table has (or once had) rules
  hastriggers	boolean	pg_class.relhastriggers	True if table has (or once had) triggers
  rowsecurity	boolean	pg_class.relrowsecurity	True if row security is enabled on the table

• pg_user

  데이터베이스 사용자에 대한 정보를 담고 있다.

  Name	Type	Description
  usename	name	User name
  usesysid	oid	ID of this user
  usecreatedb	bool	User can create databases
  usesuper	bool	User is a superuser
  userepl	bool	User can initiate streaming replication and put the system in and out of backup mode.
  usebypassrls	bool	User bypasses every row level security policy
  passwd	text	Not the password (always reads as ********)
  valuntil	abstime	Password expiry time (only used for password authentication)
  useconfig	text[]	Session defaults for run-time configuration variables

• pg_views

  View에 대한 정보를 담고 있다.

  Name	Type	References	Description
  schemaname	name	pg_namespace.nspname	Name of schema containing view
  viewname	name	pg_class.relname	Name of view
  viewowner	name	pg_authid.rolname	Name of view's owner
  definition	text		View definition (a reconstructed SELECT query)