Range types are data types representing a range of values of some element type (called the range's subtype). For instance, ranges of timestamp might be used to represent the ranges of time that a meeting room is reserved. In this case the data type is tsrange (short for "timestamp range"), and timestamp is the subtype. The subtype must have a total order so that it is well-defined whether element values are within, before, or after a range of values. Range types are useful because they represen

See Section 8.17 for an overview of range types. Table 9-49 shows the operators available for range types. Table 9-49. Range Operators Operator Description Example Result = equal int4range(1,5) = '[1,4]'::int4range t <> not equal numrange(1.1,2.2) <> numrange(1.1,2.3) t < less than int4range(1,10) < int4range(2,3) t > greater than int4range(1,10) > int4range(1,5) t <= less than or equal numrange(1.1,2.2) <= numrange(1.1,2.2) t >= greater than or equal numrange

The process of retrieving or the command to retrieve data from a database is called a query. In SQL the SELECT command is used to specify queries. The general syntax of the SELECT command is [WITH with_queries] SELECT select_list FROM table_expression [sort_specification] The following sections describe the details of the select list, the table expression, and the sort specification. WITH queries are treated last since they are an advanced feature. A simple kind of query has the form: SELECT

Name psql -- PostgreSQL interactive terminal Synopsis psql [option...] [dbname [username]] Description psql is a terminal-based front-end to PostgreSQL. It enables you to type in queries interactively, issue them to PostgreSQL, and see the query results. Alternatively, input can be from a file or from command line arguments. In addition, psql provides a number of meta-commands and various shell-like features to facilitate writing scripts and automating a wide variety of tasks. Option

The PostgreSQL type system contains a number of special-purpose entries that are collectively called pseudo-types. A pseudo-type cannot be used as a column data type, but it can be used to declare a function's argument or result type. Each of the available pseudo-types is useful in situations where a function's behavior does not correspond to simply taking or returning a value of a specific SQL data type. Table 8-25 lists the existing pseudo-types. Table 8-25. Pseudo-Types Name Description an

When an object is created, it is assigned an owner. The owner is normally the role that executed the creation statement. For most kinds of objects, the initial state is that only the owner (or a superuser) can do anything with the object. To allow other roles to use it, privileges must be granted. There are different kinds of privileges: SELECT, INSERT, UPDATE, DELETE, TRUNCATE, REFERENCES, TRIGGER, CREATE, CONNECT, TEMPORARY, EXECUTE, and USAGE. The privileges applicable to a particular object

While the server is running, it is not possible for a malicious user to take the place of the normal database server. However, when the server is down, it is possible for a local user to spoof the normal server by starting their own server. The spoof server could read passwords and queries sent by clients, but could not return any data because the PGDATA directory would still be secure because of directory permissions. Spoofing is possible because any user can start a database server; a client

NamePREPARE TRANSACTION -- prepare the current transaction for two-phase commit Synopsis PREPARE TRANSACTION transaction_id Description PREPARE TRANSACTION prepares the current transaction for two-phase commit. After this command, the transaction is no longer associated with the current session; instead, its state is fully stored on disk, and there is a very high probability that it can be committed successfully, even if a database crash occurs before the commit is requested. Once pre

NamePREPARE -- prepare a statement for execution Synopsis PREPARE name [ ( data_type [, ...] ) ] AS statement Description PREPARE creates a prepared statement. A prepared statement is a server-side object that can be used to optimize performance. When the PREPARE statement is executed, the specified statement is parsed, analyzed, and rewritten. When an EXECUTE command is subsequently issued, the prepared statement is planned and executed. This division of labor avoids repetitive parse

Namepostmaster -- PostgreSQL database server Synopsis postmaster [option...] Description postmaster is a deprecated alias of postgres. See Also postgres Prev Next postgres Up Internals