postgresql/contrib/spi
Tom Lane 0bd61548ab Solve the 'Turkish problem' with undesirable locale behavior for case
conversion of basic ASCII letters.  Remove all uses of strcasecmp and
strncasecmp in favor of new functions pg_strcasecmp and pg_strncasecmp;
remove most but not all direct uses of toupper and tolower in favor of
pg_toupper and pg_tolower.  These functions use the same notions of
case folding already developed for identifier case conversion.  I left
the straight locale-based folding in place for situations where we are
just manipulating user data and not trying to match it to built-in
strings --- for example, the SQL upper() function is still locale
dependent.  Perhaps this will prove not to be what's wanted, but at
the moment we can initdb and pass regression tests in Turkish locale.
2004-05-07 00:24:59 +00:00
..
preprocessor
autoinc.c pgindent run. 2003-08-04 00:43:34 +00:00
autoinc.example
autoinc.sql.in
insert_username.c pgindent run. 2003-08-04 00:43:34 +00:00
insert_username.example
insert_username.sql.in
Makefile $Header: -> $PostgreSQL Changes ... 2003-11-29 19:52:15 +00:00
moddatetime.c pgindent run. 2003-08-04 00:43:34 +00:00
moddatetime.example
moddatetime.sql.in
README.spi
README.timetravel
refint.c pgindent run. 2003-08-04 00:43:34 +00:00
refint.example
refint.sql.in
timetravel.c Solve the 'Turkish problem' with undesirable locale behavior for case 2004-05-07 00:24:59 +00:00
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).