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-rw-r--r--contrib/spi/README81
1 files changed, 18 insertions, 63 deletions
diff --git a/contrib/spi/README b/contrib/spi/README
index a1ab46cb2bf..65868f0fc7a 100644
--- a/contrib/spi/README
+++ b/contrib/spi/README
@@ -8,8 +8,8 @@ table/field names (as described below) while creating a trigger.
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
+ You are to create trigger (BEFORE INSERT OR UPDATE) using this
+function on a table referencing another table. You are 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.
@@ -18,8 +18,8 @@ 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
+ You are to create trigger (BEFORE DELETE OR UPDATE) using this
+function on a table referenced by another table(s). You are 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
@@ -42,26 +42,20 @@ refint.source).
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
+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,
- date_off abstime
+ date_on abstime default currabstime(),
+ date_off abstime default 'infinity'
... ...
);
-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).
+- 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
@@ -78,7 +72,7 @@ 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'
+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...
@@ -89,9 +83,12 @@ DELETE: new tuple will be inserted with stop_date setted to current date
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.
+ 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.
+
+currabstime() may be used in DEFAULT for start_date column to get
+current date.
set_timetravel() allows you turn time-travel ON/OFF for a table:
@@ -99,51 +96,9 @@ set_timetravel() allows you turn time-travel ON/OFF for a table:
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!
+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).
-
-
-5. moddatetime.c - function for maintaining a modification datetime stamp.
-
- You have to create a BEFORE UPDATE trigger using the function moddatetime().
-One argument must be given, that is the name of the field that is of type
-datetime that is to be used as the modification time stamp.
-
- There is an example in moddatetime.example.
-
- To CREATE FUNCTION use moddatetime.sql ( will be made by gmake from
-moddatetime.source).