Contents
What is a Postgres catalog?
The PostgreSQL System Catalog is a schema with tables and views that contain metadata about all the other objects inside the database and more. Some of the metadata is straightforward, and other pieces take a bit of digesting to generate real useful information.
What is the difference between a catalog and a database?
May 15, 2019 10484. A library catalog allows you to search for items owned by a specific library, including books, movies, journals, magazines, music scores, government documents, and more. Library databases allow you to efficiently search for published information such as magazine, journal, and newspaper articles.
What kind of information is in the database catalog?
metadata
A database catalog of a database instance consists of metadata in which definitions of database objects such as base tables, views (virtual tables), synonyms, value ranges, indexes, users, and user groups are stored.
What is the SQL database catalog called?
In SQL Server it is referred to as the System Catalog. In DB2 it is referred to as either the DB2 Catalog or System Catalog. In MySQL it is referred to as the Information Schema. You can think of the system catalog as a metadata repository for your databases.
How is the catalog PG _ database created in PostgreSQL?
The catalog pg_database stores information about the available databases. Databases are created with the CREATE DATABASE command. Consult Chapter 21 for details about the meaning of some of the parameters.
Unlike most system catalogs, pg_database is shared across all databases of a cluster: there is only one copy of pg_database per cluster, not one per database. Table 48-15. pg_database Columns
Where are statistics stored in PostgreSQL system catalog?
A good portion of the tables we can query in the catalog are ‘system wide’ tables, where it doesn’t matter what database we are connected to, the data represents the whole cluster, no singular database. General database info is stored in pg_database and statistics are stored in pg_stat_database.
Which is an example of a catalog query?
The following view definition joins the STV_TBL_PERM system table with the PG_CLASS, PG_NAMESPACE, and PG_DATABASE system catalog tables to return the table ID, database name, schema name, and table name. The following example returns the information for table ID 117855.