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Here are general trigger functions provided as workable examples of using SPI and triggers. "General" means that functions may be used for defining triggers for any tables but you have to specify table/field names (as described below) while creating a trigger. 1. refint.c - functions for implementing referential integrity. check_primary_key () is to used for foreign keys of a table. You have to create trigger (BEFORE INSERT OR UPDATE) using this function on a table referencing another table. You have to specify as function arguments: triggered table column names which correspond to foreign key, referenced table name and column names in referenced table which correspond to primary/unique key. You may create as many triggers as you need - one trigger for one reference. check_foreign_key () is to used for primary/unique keys of a table. You have to create trigger (BEFORE DELETE OR UPDATE) using this function on a table referenced by another table(s). You have to specify as function arguments: number of references for which function has to performe checking, action if referencing key found ('cascade' - to delete corresponding foreign key, 'restrict' - to abort transaction if foreign keys exist, 'setnull' - to set foreign key referencing primary/unique key being deleted to null), triggered table column names which correspond to primary/unique key, referencing table name and column names corresponding to foreign key (, ... - as many referencing tables/keys as specified by first argument). Note, that NOT NULL constraint and unique index have to be defined by youself. There are examples in refint.example and regression tests (sql/triggers.sql). To CREATE FUNCTIONs use refint.sql (will be made by gmake from refint.source). 2. timetravel.c - functions for implementing time travel feature. Old internally supported time-travel (TT) used insert/delete transaction commit times. To get the same feature using triggers you have to add to a table two columns of abstime type to store date when a tuple was inserted (start_date) and changed/deleted (stop_date): CREATE TABLE XXX ( ... ... date_on abstime, date_off abstime ... ... ); CREATE TRIGGER timetravel BEFORE INSERT OR DELETE OR UPDATE ON tttest FOR EACH ROW EXECUTE PROCEDURE timetravel (date_on, date_off); Tuples being inserted with NULLs in date_on/date_off will get current date in date_on (name of start_date column in XXX) and INFINITY in date_off (name of stop_date column in XXX). Tuples with stop_date equal INFINITY are "valid now": when trigger will be fired for UPDATE/DELETE of a tuple with stop_date NOT equal INFINITY then this tuple will not be changed/deleted! If stop_date equal INFINITY then on UPDATE: only stop_date in tuple being updated will be changed to current date and new tuple with new data (coming from SET ... in UPDATE) will be inserted. Start_date in this new tuple will be setted to current date and stop_date - to INFINITY. DELETE: new tuple will be inserted with stop_date setted to current date (and with the same data in other columns as in tuple being deleted). NOTE: 1. To get tuples "valid now" you have to add _stop_date_ = 'infinity' to WHERE. Internally supported TT allowed to avoid this... Fixed rewriting RULEs could help here... As work arround you may use VIEWs... 2. You can't change start/stop date columns with UPDATE! Use set_timetravel (below) if you need in this. FUNCTIONs: timetravel() is general trigger function. You have to create trigger BEFORE (!!!) INSERT OR UPDATE OR DELETE using this function on a time-traveled table. You have to specify two arguments: name of start_date column and name of stop_date column in triggered table. set_timetravel() allows you turn time-travel ON/OFF for a table: set_timetravel('XXX', 1) will turn TT ON for table XXX (and report old status). set_timetravel('XXX', 0) will turn TT OFF for table XXX (-"-). Turning TT OFF allows you do with a table ALL what you want! There is example in timetravel.example. To CREATE FUNCTIONs use timetravel.sql (will be made by gmake from timetravel.source). 3. autoinc.c - function for implementing AUTOINCREMENT/IDENTITY feature. You have to create BEFORE INSERT OR UPDATE trigger using function autoinc(). You have to specify as function arguments: column name (of int4 type) for which you want to get this feature and name of SEQUENCE from which next value has to be fetched when NULL or 0 value is being inserted into column (, ... - you are able to specify as many column/sequence pairs as you need). There is example in autoinc.example. To CREATE FUNCTION use autoinc.sql (will be made by gmake from autoinc.source). 4. insert_username.c - function for inserting user names. You have to create BEFORE INSERT OR UPDATE trigger using the function insert_username(). You have to specify as a function argument: the column name (of text type) in which user names will be inserted. Note that user names will be inserted irregardless of the initial value of the field, so that users cannot bypass this functionality by simply defining the field to be NOT NULL. There is an example in insert_username.example. To CREATE FUNCTION use insert_username.sql (will be made by gmake from insert_username.source).