I have a view in mysql which is made of three tables unioned together:
CREATE VIEW program_operator_jct_view AS
select
program_id,
operator_code,
'PROGRAM_OPERATOR' AS type
from
program_operator_jct
UNION
(select
program_id,
operator_code,
'PROGRAM_GROUP' AS type
from
program_operator_group_jct pg_jct,
operator_group_jct og_jct
where
pg_jct.group_id = og_jct.group_id)
From this view, I create a summary table for increased performance, which is indexed so my results from this summary table can be returned via covering indexes:
CREATE TABLE `program_operator_jct_summary` (
`program_id` int(7) NOT NULL,
`operator_code` varchar(6) NOT NULL,
PRIMARY KEY (`program_id`,`operator_code`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1
//BUILD SUMMARY PROCEDURE
delimiter //
CREATE PROCEDURE update_program_operator_jct_summary ()
BEGIN
DELETE FROM program_operator_jct_summary;
INSERT INTO program_operator_jct_summary select DISTINCT program_id, operator_code from program_operator_jct_view;
INSERT INTO trigger_record (name) VALUES ('update_program_operator_jct_summary');
END
//
I attached this procedure to the insert, update and delete triggers of the underlining tables which make up the summary table:
-program_operator_jct
-program_operator_group_jct
-operator_group_jct
EXAMPLE:
delimiter //
CREATE TRIGGER trigger_program_operator_jct_insert AFTER INSERT ON program_operator_j开发者_StackOverflowct
FOR EACH ROW
BEGIN
CALL update_program_operator_jct_summary ();
END
//
Here's my problem when I add (5) operators to the program_operator_jct:
INSERT INTO program_operator_jct (program_id, operator_code) VALUES
('112', '000500'),
('112', '000432'),
('112', '000501'),
('112', '000264'),
('112', '000184')
This trigger runs (5) times, if I add 100 operators this trigger runs 100 times. This is a nice place to use triggers because I don't have to worry about the summary table being out of date with the underlining tables.
However rebuilding a summary table for each value in an extended inserts is way too much of a performance hit (sometimes I add hundreds of operators to programs at a time). I want the trigger to run once after the extended inserts are performed on the underlining tables. Is this possible?
The trigger is doing its job, e.g. 'FOR EACH ROW'.
I don't believe that mysql gives you the option of running a trigger once at the end.
I'd call the stored procedure from your code after the INSERT has successfully completed.
If you're worried about forgetting, setup a cron job to run it every once in a while.
Good luck.
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