Postgresql: Documentation: 9.5: Truncate

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PostgreSQL provides a large number of functions and operators for the built-in data types. This chapter describes most of them, although additional special-purpose functions appear in relevant sections of the manual. Users can also define their own functions and operators, as described in Part V. The psql commands \df and \do can be used to list all available functions and operators 9.9. Date/Time Functions and Operators Table 9-27 shows the available functions for date/time value processing, with details appearing in the following subsections. Table 9-26 illustrates the behaviors of the basic arithmetic operators (+, *, etc.). For formatting functions, refer to Section 9.8. You should be familiar with the background information on date/time data types from Description TRUNCATE quickly removes all rows from a set of tables. It has the same effect as an unqualified DELETE on each table, but since it does not actually scan the tables it is faster. Furthermore, it reclaims disk space immediately, rather than requiring a subsequent VACUUM operation. This is most useful on large tables.

PostgreSQL: Documentation: 9.2: TRUNCATE

Description TRUNCATE quickly removes all rows from a table. It has the same effect as an unqualified DELETE but since it does not actually scan the table it is faster. 4 shows This is most useful on large tables. TRUNCATE cannot be executed inside a transaction block (BEGIN / COMMIT pair), because there is no way to roll it back.

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TRUNCATE Specifies that VACUUM should attempt to truncate off any empty pages at the end of the table and allow the disk space for the truncated pages to be returned to attempt to truncate off any the operating system. This is normally the desired behavior and is the default unless the vacuum_truncate option has been set to false for the table to be vacuumed.

Description ALTER DEFAULT PRIVILEGES allows you to set the privileges that will be applied to objects created in the future. (It does not affect privileges assigned to already-existing objects.) Privileges can be set globally (i.e., for all objects created in the current database), or just for objects created in specified schemas. While you can change your own default privileges and Description TRUNCATE quickly removes all rows from a set of tables. It has the same effect using information contained in as an unqualified DELETE on each table, but since it does not actually scan the tables it is faster. Furthermore, it reclaims disk space immediately, rather than requiring a subsequent VACUUM operation. This is most useful on large tables. 9.9.2. date_trunc # The function date_trunc is conceptually similar to the trunc function for numbers. date_trunc(field, source [, time_zone ]) source is a value expression of type timestamp, timestamp with time zone, or interval.

Description TRUNCATE quickly removes all rows from a set of tables. It has the same effect as an unqualified DELETE on each table, but since it does not actually scan the tables it is faster. Furthermore, it reclaims disk space immediately, rather than requiring a subsequent VACUUM operation. This is most useful on large tables. 40.9.1. Triggers on Data Changes PL/pgSQL can be used to define trigger procedures. A trigger procedure is created with the CREATE FUNCTION command, declaring it as a function with no arguments and a return type of trigger. Note that the function must be declared with no arguments even if it expects to receive arguments specified in CREATE TRIGGER — trigger arguments Table 8.4 shows the general-purpose character types available in PostgreSQL. SQL defines two primary character types: character varying(n) and character(n), where n is a positive integer. Both of these types can store strings up to n characters (not bytes) in length. An attempt to store a longer string into a column of these types will result in an error, unless the excess characters

PostgreSQL: Documentation: 17: pg_dump
PostgreSQL: Documentation: 12: TRUNCATE
PostgreSQL: Documentation: 9.2: TRUNCATE

9.8. Data Type Formatting Functions # The PostgreSQL formatting functions provide a powerful set of tools for converting various data types TRUNCATE removes the entire content of the table immediately, without requiring a subsequent VACUUM or VACUUM FULL to reclaim the now-unused disk space. The disadvantage is that strict MVCC semantics are violated.

TRUNCATE

Description TRUNCATE quickly removes all rows from a set of tables. It has the same effect as an unqualified DELETE are provided for many on each table, but since it does not actually scan the tables it is faster. This is most useful on large tables.

Note PostgreSQL does not support CHECK constraints that reference table data other than the new or updated row being checked. While a CHECK constraint that violates this rule may appear to work in simple tests, it cannot guarantee that the database will not reach a state in which the constraint condition is false (due to subsequent changes of the other row (s) involved). This These TRUNCATE quickly removes all rows settings control the behavior of the built-in streaming replication feature (see Section 26.2.5), and the built-in logical replication feature (see Chapter 29). For streaming replication, servers will be either a primary or a standby server. Primaries can send data, while standbys are always receivers of replicated data. When cascading replication (see Section 26.2.7) is used,

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 vary depending on Description TRUNCATE quickly removes all rows from a set of tables. It has the same effect as an unqualified DELETE on each table, but since it does not actually scan the tables it is faster. Furthermore, it reclaims disk space immediately, rather than requiring a subsequent VACUUM operation. This is most useful on large tables. 37.1. Overview of Trigger Behavior # A trigger is a specification that the database should automatically execute a particular function whenever

PostgreSQL: Documentation: 9.5: Row Security Policies
PostgreSQL: Documentation: 17: 9.8. Data Type Formatting Functions
PostgreSQL: Documentation: 17: Chapter 14. Performance Tips
PostgreSQL: Documentation: 9.1: TRUNCATE
PostgreSQL: Documentation: 8.4: Date/Time Functions and Operators

Description pg_dump is a utility for backing up a PostgreSQL database. It makes consistent backups even if the database is being used concurrently. pg_dump does not block other users accessing the database (readers or writers). pg_dump only dumps a single database. To back up an entire cluster, or to back up global objects that are common to all databases in a cluster Description TRUNCATE quickly removes all rows from a set of tables. It has the same effect as an unqualified DELETE on each table, but since it does not actually scan the tables it is faster. Furthermore, it reclaims disk space immediately, rather than requiring a subsequent VACUUM operation. This is most useful on large tables. Description TRUNCATE quickly removes all rows from a set of tables. It has the same effect as an unqualified DELETE on each table, but since it does not actually scan the tables it is faster. Furthermore, it reclaims disk space immediately, rather than requiring a subsequent VACUUM operation. This is most useful on large tables.

The lo module provides support for managing Large Objects (also called LOs or BLOBs). This includes a data type lo and a trigger lo_manage. This module is considered “trusted”, that is, it can be installed by non-superusers who have CREATE privilege on the current database. E.26.1. Overview Major enhancements in PostgreSQL 9.5 include: Allow INSERT s that would generate constraint conflicts to be turned into UPDATE s or ignored Add GROUP BY analysis features GROUPING SETS, CUBE and ROLLUP Add row-level security control Create mechanisms for tracking the progress of replication, including methods for identifying the origin

Tip TRUNCATE provides a faster mechanism to remove all rows from a table. There are two ways to delete rows in a table using information contained in other tables in the database: using sub-selects, or specifying additional tables in the USING clause. Which technique is more appropriate replication feature see depends on the specific circumstances. Mathematical operators are provided for many PostgreSQL types. For types without standard mathematical conventions (e.g., date/time types) we describe the actual behavior in subsequent sections. Table 9.4 shows the available mathematical operators.

Documentation → PostgreSQL 9.5 Supported Versions: Current (17) / 16 / 15 / 14 / 13 Development Versions: 18 / devel Unsupported versions: 12 / 11 / 10 / 9.6 / 9.5 Looking for documentation for an older, unsupported, version? Check the archive of older manuals. Description TRUNCATE quickly removes all rows from a set of tables. It has the same effect as an unqualified DELETE on each table, but since it does not actually scan the tables it is faster. Furthermore, it reclaims disk space immediately, rather than requiring a subsequent VACUUM operation. This is most useful on large tables.

Description pg_restore is a utility for restoring a PostgreSQL database from an archive created by pg_dump in one of the non-plain-text formats. It will issue the commands necessary to reconstruct the database to the state it was in at the time it was saved. The archive files also allow pg_restore to be selective about what is restored, or even to reorder the items prior to being restored. The

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Postgresql: Documentation: 9.5: Truncate

PostgreSQL: Documentation: 9.2: TRUNCATE