历史版本。 PostgreSQL 9.1 已结束支持。 2016-10-27. 请参阅 当前版本手册.
45.42. pg_trigger #
目录pg_trigger存储表和视图上的触发器。详见CREATE TRIGGER。
表 45.42. pg_trigger 列
| Name | Type | References | Description |
|---|---|---|---|
tgrelid | oid | | The table this trigger is on |
tgname | name | Trigger name (must be unique among triggers of same table) | |
tgfoid | oid | | The function to be called |
tgtype | int2 | Bit mask identifying trigger firing conditions | |
tgenabled | char | Controls in which session_replication_role modes
the trigger fires.
O = trigger fires in “origin” and “local” modes,
D = trigger is disabled,
R = trigger fires in “replica” mode,
A = trigger fires always.
| |
tgisinternal | bool | True if trigger is internally generated (usually, to enforce
the constraint identified by tgconstraint) | |
tgconstrrelid | oid | | The table referenced by a referential integrity constraint |
tgconstrindid | oid | | The index supporting a unique, primary key, or referential integrity constraint |
tgconstraint | oid | | The pg_constraint entry associated with the trigger, if any |
tgdeferrable | bool | True if constraint trigger is deferrable | |
tginitdeferred | bool | True if constraint trigger is initially deferred | |
tgnargs | int2 | Number of argument strings passed to trigger function | |
tgattr | int2vector | | Column numbers, if trigger is column-specific; otherwise an empty array |
tgargs | bytea | Argument strings to pass to trigger, each NULL-terminated | |
tgqual | pg_node_tree | Expression tree (in nodeToString()
representation) for the trigger's WHEN condition, or null
if none |
当前，列限定触发器只支持UPDATE事件，因此tgattr只用于这种事件类型。tgtype也可以包含用于其他事件类型的位，但那些事件类型对应的是表级触发器，并且会忽略tgattr。
注意
当tgconstraint非零时，tgconstrrelid、tgconstrindid、tgdeferrable和tginitdeferred与被引用的pg_constraint 项有很大的冗余。但是，存在将一个不可延迟触发器关联到一个可延迟约束的可能性：外键约束可以有一些可延迟和一些不可延迟触发器。
注意
如果一个关系在本目录中拥有任何触发器，其pg_class.relhastriggers必须为真。