A column can be assigned a default value. When a new row is created and no values are specified for some of the columns, those columns will be filled with their respective default values. A data manipulation command can also request explicitly that a column be set to its default value, without having to know what that value is. (Details about data manipulation commands are in Chapter 6.) If no default value is declared explicitly, the default value is the null value. This usually makes sense be

The catalog pg_operator stores information about operators. See CREATE OPERATOR and Section 36.12 for more information. Table 50-34. pg_operator Columns Name Type References Description oid oid Row identifier (hidden attribute; must be explicitly selected) oprname name Name of the operator oprnamespace oid pg_namespace.oid The OID of the namespace that contains this operator oprowner oid pg_authid.oid Owner of the operator oprkind char b = infix ("both"), l = prefix ("left"), r = postf

The catalog pg_auth_members shows the membership relations between roles. Any non-circular set of relationships is allowed. Because user identities are cluster-wide, pg_auth_members is shared across all databases of a cluster: there is only one copy of pg_auth_members per cluster, not one per database. Table 50-9. pg_auth_members Columns Name Type References Description roleid oid pg_authid.oid ID of a role that has a member member oid pg_authid.oid ID of a role that is a member of roleid gr

Namepg_upgrade -- upgrade a PostgreSQL server instance Synopsis pg_upgrade -b oldbindir -B newbindir -d olddatadir -D newdatadir [option...] Description pg_upgrade (formerly called pg_migrator) allows data stored in PostgreSQL data files to be upgraded to a later PostgreSQL major version without the data dump/reload typically required for major version upgrades, e.g. from 8.4.7 to the current major release of PostgreSQL. It is not required for minor version upgrades, e.g. from 9.0.1 to

NameDROP FUNCTION -- remove a function Synopsis DROP FUNCTION [ IF EXISTS ] name ( [ [ argmode ] [ argname ] argtype [, ...] ] ) [ CASCADE | RESTRICT ] Description DROP FUNCTION removes the definition of an existing function. To execute this command the user must be the owner of the function. The argument types to the function must be specified, since several different functions can exist with the same name and different argument lists. Parameters IF EXISTS Do not throw an er

NameALTER DEFAULT PRIVILEGES -- define default access privileges Synopsis ALTER DEFAULT PRIVILEGES [ FOR { ROLE | USER } target_role [, ...] ] [ IN SCHEMA schema_name [, ...] ] abbreviated_grant_or_revoke where abbreviated_grant_or_revoke is one of: GRANT { { SELECT | INSERT | UPDATE | DELETE | TRUNCATE | REFERENCES | TRIGGER } [, ...] | ALL [ PRIVILEGES ] } ON TABLES TO { [ GROUP ] role_name | PUBLIC } [, ...] [ WITH GRANT OPTION ] GRANT { { USAGE | SELECT | UP

Dictionaries are used to eliminate words that should not be considered in a search (stop words), and to normalize words so that different derived forms of the same word will match. A successfully normalized word is called a lexeme. Aside from improving search quality, normalization and removal of stop words reduce the size of the tsvector representation of a document, thereby improving performance. Normalization does not always have linguistic meaning and usually depends on application semantic

It is frequently convenient to group users together to ease management of privileges: that way, privileges can be granted to, or revoked from, a group as a whole. In PostgreSQL this is done by creating a role that represents the group, and then granting membership in the group role to individual user roles. To set up a group role, first create the role: CREATE ROLE name; Typically a role being used as a group would not have the LOGIN attribute, though you can set it if you wish. Once the grou

There are several ways to shut down the database server. You control the type of shutdown by sending different signals to the master postgres process. SIGTERM This is the Smart Shutdown mode. After receiving SIGTERM, the server disallows new connections, but lets existing sessions end their work normally. It shuts down only after all of the sessions terminate. If the server is in online backup mode, it additionally waits until online backup mode is no longer active. While backup mode is activ

GIN stands for Generalized Inverted Index. GIN is designed for handling cases where the items to be indexed are composite values, and the queries to be handled by the index need to search for element values that appear within the composite items. For example, the items could be documents, and the queries could be searches for documents containing specific words. We use the word item to refer to a composite value that is to be indexed, and the word key to refer to an element value. GIN always st