An alternative to the built-in standby mode described in the previous sections is to use a restore_command that polls the archive location. This was the only option available in versions 8.4 and below. In this setup, set standby_mode off, because you are implementing the polling required for standby operation yourself. See the pg_standby module for a reference implementation of this. Note that in this mode, the server will apply WAL one file at a time, so if you use the standby server for queri

NameSELECT, TABLE, WITH -- retrieve rows from a table or view Synopsis [ WITH [ RECURSIVE ] with_query [, ...] ] SELECT [ ALL | DISTINCT [ ON ( expression [, ...] ) ] ] [ * | expression [ [ AS ] output_name ] [, ...] ] [ FROM from_item [, ...] ] [ WHERE condition ] [ GROUP BY grouping_element [, ...] ] [ HAVING condition [, ...] ] [ WINDOW window_name AS ( window_definition ) [, ...] ] [ { UNION | INTERSECT | EXCEPT } [ ALL | DISTINCT ] select ] [ ORDER BY

It is possible to use SSH to encrypt the network connection between clients and a PostgreSQL server. Done properly, this provides an adequately secure network connection, even for non-SSL-capable clients. First make sure that an SSH server is running properly on the same machine as the PostgreSQL server and that you can log in using ssh as some user. Then you can establish a secure tunnel with a command like this from the client machine: ssh -L 63333:localhost:5432 joe@foo.com The first numbe

19.9.1. Query and Index Statistics Collector These parameters control server-wide statistics collection features. When statistics collection is enabled, the data that is produced can be accessed via the pg_stat and pg_statio family of system views. Refer to Chapter 28 for more information. track_activities (boolean) Enables the collection of information on the currently executing command of each session, along with the time when that command began execution. This parameter is on by default.

When you create a table and you realize that you made a mistake, or the requirements of the application change, you can drop the table and create it again. But this is not a convenient option if the table is already filled with data, or if the table is referenced by other database objects (for instance a foreign key constraint). Therefore PostgreSQL provides a family of commands to make modifications to existing tables. Note that this is conceptually distinct from altering the data contained in

Namereindexdb -- reindex a PostgreSQL database Synopsis reindexdb [connection-option...] [option...] [ --schema | -S schema ] ... [ --table | -t table ] ... [ --index | -i index ] ... [dbname] reindexdb [connection-option...] [option...] --all | -a reindexdb [connection-option...] [option...] --system | -s [dbname] Description reindexdb is a utility for rebuilding indexes in a PostgreSQL database. reindexdb is a wrapper around the SQL command REINDEX. There is no effective difference be

The genetic algorithm (GA) is a heuristic optimization method which operates through randomized search. The set of possible solutions for the optimization problem is considered as a population of individuals. The degree of adaptation of an individual to its environment is specified by its fitness. The coordinates of an individual in the search space are represented by chromosomes, in essence a set of character strings. A gene is a subsection of a chromosome which encodes the value of a single p

The task of the planner/optimizer is to create an optimal execution plan. A given SQL query (and hence, a query tree) can be actually executed in a wide variety of different ways, each of which will produce the same set of results. If it is computationally feasible, the query optimizer will examine each of these possible execution plans, ultimately selecting the execution plan that is expected to run the fastest. Note: In some situations, examining each possible way in which a query can be exe

Namepg_restore -- restore a PostgreSQL database from an archive file created by pg_dump Synopsis pg_restore [connection-option...] [option...] [filename] 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

The catalog pg_amop stores information about operators associated with access method operator families. There is one row for each operator that is a member of an operator family. A family member can be either a search operator or an ordering operator. An operator can appear in more than one family, but cannot appear in more than one search position nor more than one ordering position within a family. (It is allowed, though unlikely, for an operator to be used for both search and ordering purpos