Gbase 8C system table PG_ class

pg_class System tables store database object information and the relationship between them .

name	type	quote	describe
oid	oid		Row identifier （ Hidden attribute , Must be explicitly selected to display ）
relname	name		surface 、 Indexes 、 Name of view, etc
relnamespace	oid	pg_namespace.oid	The name of the namespace that contains the relationship OID
reltype	oid	pg_type.oid	Data types corresponding to possible table row types OID（ The index is 0, No index pg_type term ）
reloftype	oid	pg_type.oid	For tables with types , For the underlying composite type OID, For all other relationships 0
relowner	oid	pg_authid.oid	The owner of the relationship
relam	oid	pg_am.oid	If this is an index , Indicates the access method used by the index （B Trees 、 Hash, etc ）
relfilenode	oid		The name of the disk file for the relationship ,0 That means this is one “ mapping ” Relationship , The disk file name depends on the low-level state
reltablespace	oid	pg_tablespace.oid	The tablespace that the relationship stores . If 0, Use the default tablespace of the database .（ If the relationship is meaningless without disk files ）
relpages	int4		This table shows the size of the disk , In pages （ The page size is BLCKSZ）. This is just an estimate used by the planner . It has been VACUUM、ANALYZE As well as some DDL command （ Such as CREATE INDEX） Updated .
reltuples	float4		Number of rows in the table . This is just an estimate used by the planner . It has been VACUUM、ANALYZE As well as some DDL command （ Such as CREATE INDEX） Updated .
relallvisible	int4		The number of pages marked as fully visible in the table's visibility mapping table . This is just an estimate used by the planner . It has been VACUUM、ANALYZE As well as some DDL command （ Such as CREATE INDEX） Updated .
reltoastrelid	oid	pg_class.oid	Associated with this table TOAST Tabular OID, If not, it is 0.TOAST The table will have large attributes “ Off line ” Stored in a secondary table .
relhasindex	bool		If this is a table and there is （ Or recently built ） The index is true
relisshared	bool		True if the table is shared among all databases in the cluster . Only some system directories （ Such as pg_database） Is Shared .
relpersistence	char		p = A permanent watch ,u = No log table , t = A temporary table
relkind	char		r = Common watch ,i = Indexes , S = Sequence ,t = TOAST surface ,v = View , m = Materialized view , c = Combination type , f = External table , p = Partition table
relnatts	int2		The number of user columns in the relationship （ System columns are not counted ）. stay pg_attribute There must be so many corresponding items in . See also pg_attribute.attnum.
relchecks	int2		On the table CHECK Number of constraints
relhasoids	bool		If one is generated for each row of the relationship OID It is true
relhaspkey	bool		If the table has （ Or have ） A primary key is true
relhasrules	bool		If the table has （ Or have ） The rule is true
relhastriggers	bool		If the table has （ Or have ） The trigger is true
relhassubclass	bool		If the table has （ Or have ） Any inherited child is true
relrowsecurity	bool		True if row level security is enabled on the table
relforcerowsecurity	bool		If row level security （ When enabled ） If it also applies to the table owner, it is true
relispopulated	bool		True if the table has been filled （ This column is true for all relationships , But for some materialized views, it is not ）
relreplident	char		Used to form... For rows “replica identity” The column of ： d = Default ( Primary key , If there is ), n = nothing , f = All columns i = Indexed indisreplident Set or default
relispartition	bool		If the table is partitioned , It is true
relfrozenxid	xid		All transactions before ID Has been replaced in the table with a permanent （“ Frozen ”) Business ID. This is used to track whether the table needs to be cleaned up , To prevent transactions ID Roll back or allow pg_xact Contracted . If the relationship is not a table, it is 0（InvalidTransactionId）.
relminmxid	xid		Multiple transactions prior to this ID It has been replaced with a transaction in the table ID. This is used to track whether the table needs to be cleaned up , To prevent A lot of business ID Roll back or allow pg_multixact Contracted . If the relationship is not a table by 0（InvalidMultiXactId）.
relacl	aclitem[]		Access right
reloptions	text[]		Access method related options , With “keyword=value” String form
relpartbound	pg_node_tree		If the table is partitioned （ see also relispartition）, Is the internal representation of partition binding