Appendix

System Catalogs

This section describes the System Catalogs provided by AgensGraph. System Catalogs store schema metadata. The list of System Catalogs provided by AgensGraph is shown below; refer to the link for the catalogs of PostgreSQL.

Catalog Name	Purpose
ag_graph	A list of graphs created in the DB
ag_label	A list of labels created in the DB
ag_graphmeta	Meta information between labels

ag_graph

Shows a list of graphs created in the DB. One graph corresponds with one schema.

• ag_graph columns

  Name	Type	Description
  graphname	name	Graph name
  nspid	oid	Oid of the associated schema (= namespace)

ag_label

Shows a list of labels created in the DB. One label corresponds with one table (relation) (one-to-one correspondence).

• ag_label columns

  Name	Type	Description
  labname	name	Label name
  nspid	oid	oid of the graph belonging
  labid	int32	Sequential id to distinguish labels in the same graph
  relid	relid	oid of linked table (relation)
  labkind	char	This item has a value of either V or E. V: vertex label E: edge label

ag_graphmeta

Stores meta information between labels and is used for identifying the graph model.

• ag_graphmeta columns

  Name	Type	Description
  graph	oid	Graph oid
  edge	int16	labid of edge
  start	int16	labid of start vertex
  end	int16	labid of end vertex
  edgecount	int16	The number of the same edges between start/end labels

System Views

Describes the System Views provided by AgensGraph. In addition to the System Catalogs, there are other views that provide intuitive information to users. The list of System Views provided by AgensGraph is shown below; refer to the link for the views of PostgreSQL.

Catalog Name	Purpose
ag_property_indexes	List of property indexes
ag_graphmeta_view	Provides graph_meta information as object name

ag_property_indexes

Displays a list of property indexes.

• ag_property_indexes columns

  Name	Type	Description
  graphname	name	Graph name
  labelname	name	Label name
  indexname	name	Property index name
  tablespace	name	Tablespace name
  unique	boolean	Whether duplicates are allowed or not
  indexdef	text	The query statement used to create the index
  owner	name	index owners
  size	text	index size
  description	text	index description (comment)

ag_graphmeta_view

ag_graphmeta is a view that provides intuitive information.

• ag_graphmeta_view columns

  Name	Type	Description
  graphname	name	Graph name
  start	name	start vlabel name
  edge	name	edge name
  end	name	end vlabel name
  edgecount	bigint	The number of the same edges between start/end labels