Postgresql 中文操作指南
Description
DISCARD 释放与数据库会话关联的内部资源。此命令对于部分或完全重置会话的状态非常有用。有几个子命令用于释放不同类型的资源； DISCARD ALL 变体子命令包含所有其他子命令，并重置其他状态。
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
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PLANS
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Releases all cached query plans, forcing re-planning to occur the next time the associated prepared statement is used.
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SEQUENCES
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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.)
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TEMPORARY or TEMP
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Drops all temporary tables created in the current session.
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ALL
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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:
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CLOSE ALL;
SET SESSION AUTHORIZATION DEFAULT;
RESET ALL;
DEALLOCATE ALL;
UNLISTEN *;
SELECT pg_advisory_unlock_all();
DISCARD PLANS;
DISCARD TEMP;
DISCARD SEQUENCES;