info > DISCARD

🗂️ DISCARD(7) — PostgreSQL 14.23 Documentation

📛 NAME

DISCARD – discard session state

🚀 Quick Reference

Use Case	Command	Description
🧹 Full session reset	DISCARD ALL	Release all temporary resources and reset session to initial state
📋 Clear cached query plans	DISCARD PLANS	Force re‑planning of prepared statements
🔢 Discard sequence state	DISCARD SEQUENCES	Clear currval(), lastval() and preallocated values
🗑️ Drop temporary tables	DISCARD TEMP	Remove all temporary tables in current session

📖 SYNOPSIS

DISCARD { ALL | PLANS | SEQUENCES | TEMPORARY | TEMP }

📝 DESCRIPTION

DISCARD releases internal resources associated with a database session. This command is useful for partially or fully resetting the session’s state. There are several subcommands to release different types of resources; the DISCARD ALL variant subsumes all the others, and also resets additional state.

⚙️ PARAMETERS

📄 PLANS

Releases all cached query plans, forcing re‑planning to occur the next time the associated prepared statement is used.

🔢 SEQUENCES

Discards all cached sequence‑related state, including currval()/lastval() information and any preallocated sequence values that have not yet been returned by nextval(). (See CREATE SEQUENCE for a description of preallocated sequence values.)

🗑️ TEMPORARY or TEMP

Drops all temporary tables created in the current session.

🌐 ALL

Releases all temporary resources associated with the current session and resets the session to its initial state. Currently, this has the same effect as executing the following sequence of statements:

CLOSE ALL;
SET SESSION AUTHORIZATION DEFAULT;
RESET ALL;
DEALLOCATE ALL;
UNLISTEN *;
SELECT pg_advisory_unlock_all();
DISCARD PLANS;
DISCARD TEMP;
DISCARD SEQUENCES;

📌 NOTES

DISCARD ALL cannot be executed inside a transaction block.

🔗 COMPATIBILITY

DISCARD is a PostgreSQL extension.

📧 DISCARD(8postfix) — Postfix discard mail delivery agent

📛 NAME

discard – Postfix discard mail delivery agent

🚀 Quick Reference

Use Case	Command	Description
🔧 Discard mail with reason	discard (via master.cf)	Pretends to deliver, logs reason, marks recipients finished or retries later
⚙️ Reload config	postfix reload	Speed up pickup of main.cf changes

📖 SYNOPSIS

discard [generic Postfix daemon options]

📝 DESCRIPTION

The Postfix discard(8) delivery agent processes delivery requests from the queue manager. Each request specifies a queue file, a sender address, a next‑hop destination that is treated as the reason for discarding the mail, and recipient information. The reason may be prefixed with an RFC 3463‑compatible detail code. This program expects to be run from the master(8) process manager.

The discard(8) delivery agent pretends to deliver all recipients in the delivery request, logs the “next‑hop” destination as the reason for discarding the mail, updates the queue file, and either marks recipients as finished or informs the queue manager that delivery should be tried again at a later time.

Delivery status reports are sent to the trace(8) daemon as appropriate.

🔒 SECURITY

The discard(8) mailer is not security‑sensitive. It does not talk to the network, and can be run chrooted at fixed low privilege.

📜 STANDARDS

RFC 3463 (Enhanced Status Codes)

🔍 DIAGNOSTICS

Problems and transactions are logged to syslogd(8) or postlogd(8).

Depending on the setting of the notify_classes parameter, the postmaster is notified of bounces and of other trouble.

⚙️ CONFIGURATION PARAMETERS

Changes to main.cf are picked up automatically as discard(8) processes run for only a limited amount of time. Use the command postfix reload to speed up a change.

The text below provides only a parameter summary. See postconf(5) for more details including examples.

• config_directory (see 'postconf -d' output) — The default location of the Postfix main.cf and master.cf configuration files.
• daemon_timeout (18000s) — How much time a Postfix daemon process may take to handle a request before it is terminated by a built‑in watchdog timer.
• delay_logging_resolution_limit (2) — The maximal number of digits after the decimal point when logging sub‑second delay values.
• double_bounce_sender (double-bounce) — The sender address of postmaster notifications that are generated by the mail system.
• ipc_timeout (3600s) — The time limit for sending or receiving information over an internal communication channel.
• max_idle (100s) — The maximum amount of time that an idle Postfix daemon process waits for an incoming connection before terminating voluntarily.
• max_use (100) — The maximal number of incoming connections that a Postfix daemon process will service before terminating voluntarily.
• process_id (read-only) — The process ID of a Postfix command or daemon process.
• process_name (read-only) — The process name of a Postfix command or daemon process.
• queue_directory (see 'postconf -d' output) — The location of the Postfix top‑level queue directory.
• syslog_facility (mail) — The syslog facility of Postfix logging.
• syslog_name (see 'postconf -d' output) — A prefix that is prepended to the process name in syslog records, so that, for example, “smtpd” becomes “prefix/smtpd”.
• service_name (read-only) — Available in Postfix 3.3 and later. The master.cf service name of a Postfix daemon process.

👁️ SEE ALSO

• qmgr(8) – queue manager
• bounce(8) – delivery status reports
• error(8) – Postfix error delivery agent
• postconf(5) – configuration parameters
• master(5) – generic daemon options
• master(8) – process manager
• postlogd(8) – Postfix logging
• syslogd(8) – system logging

📄 LICENSE

The Secure Mailer license must be distributed with this software.

📅 HISTORY

This service was introduced with Postfix version 2.2.

👤 AUTHOR(S)

Victor Duchovni
Morgan Stanley

Based on code by:
Wietse Venema
IBM T.J. Watson Research
P.O. Box 704
Yorktown Heights, NY 10598, USA

Wietse Venema
Google, Inc.
111 8th Avenue
New York, NY 10011, USA