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.. | ||
preprocessor | ||
autoinc.c | ||
autoinc.example | ||
autoinc.sql.in | ||
insert_username.c | ||
insert_username.example | ||
insert_username.sql.in | ||
Makefile | ||
moddatetime.c | ||
moddatetime.example | ||
moddatetime.sql.in | ||
README.spi | ||
README.timetravel | ||
refint.c | ||
refint.example | ||
refint.sql.in | ||
timetravel.c | ||
timetravel.example | ||
timetravel.sql.in |
2. timetravel.c - functions for implementing time travel feature. !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! I rewritten this, because: on original version of postgresql 7.3.2-7.3.3: the UPDATE not work on timetravel.example if I added >create unique index tttest_idx on tttest (price_id,price_off); >update tttest set price_val = 30 where price_id = 3; ERROR: Cannot insert a duplicate key into unique index tttest_idx And UPDATE not work on table tttest after >alter table tttest add column q1 text; >alter table tttest add column q2 int; >alter table tttest drop column q1; >update tttest set price_val = 30 where price_id = 3; ERROR: Parameter '$5' is out of range And I add a new optional feature: my new timetravel have +3 optional parameters: inserter_user, updater_user, deleter_user. And I add a new function: get_timetravel for get timetravel status without change it. A big difference: the old version on UPDATE changed oid on active ('infinity') record, the new version UPDATE keep oid, and the overdued record have a new oid. I sign with '!!!' my comment in this file. !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Old internally supported time-travel (TT) used insert/delete transaction commit times. To get the same feature using triggers you are 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 default currabstime(), date_off abstime default 'infinity' ... ... /* !!! and (if have) */ ins_user text /* user, who insert this record */ upd_user text /* user, who updated this record */ del_user text /* user, who deleted this record */ ... ... ); !!! on INSERT my new version: ... and optionally set ins_user to current user, upd_user and del_user to null. - so, 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: original version was: 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. On my new version: insert a new tuple with old values, but stop_date changed to current date; and update original tuple with new data, and update start_date to current date and optionally set upd_user to current user and clear ins_user,del_user. 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). On my new version: ... and optionally set del_user to current user. NOTE: 1. To get tuples "valid now" you are 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 are to create trigger BEFORE UPDATE OR DELETE using this function on a time-traveled table. You are to specify two arguments: name of start_date column and name of stop_date column in triggered table. Or add +3 arguments: name of insert_user column, name of update_user column, name of delete_user column currabstime() may be used in DEFAULT for start_date column to get current date. !!! I deleted this function, because I newer used this. 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. get_timetravel() reports time-travel status ON(1)/OFF(0) for a table. get_timetravel() and set_timetravel() not checking existing of table and existing of timetravel trigger on specified table. There is example in timetravel.example. To CREATE FUNCTIONs use timetravel.sql (will be made by gmake from timetravel.source).