Move rows from TableA into Table-Archive - mysql

Question

Is it possible to move rows that are 3 days old into an other table called "Table_Archive" automatically in mysql ones a week?
tableA ex:
ID | stringvalue | Timestamp
1 | abc | 2011-10-01
2 | abc2 | 2011-10-02
3 | abc3 | 2011-10-05
4 | abc4 | 2011-10-10
5 | abc5 | 2011-10-11
After the move
tableA:
ID | stringvalue | Timestamp
4 | abc4 | 2011-10-10
5 | abc5 | 2011-10-11
Table_Archive:
ID | stringvalue | Timestamp
1 | abc | 2011-10-01
2 | abc2 | 2011-10-02
3 | abc3 | 2011-10-05
And when new input comes into tableA it wont be any problems with ID (PK) in the next move?
What Ive got:
CREATE PROCEDURE clean_tables ()
BEGIN
BEGIN TRANSACTION;
DECLARE _now DATETIME;
SET _now := NOW();
INSERT
INTO Table_Archive
SELECT *
FROM TableA
WHERE timestamp < _now - 3;
FOR UPDATE;
DELETE
FROM TableA
WHERE timestamp < _now - 3;
COMMIT;
END
How do I change _now to be the date 3 days ago?

Answer 1

Personally, I would make use of the MySQL Event Scheduler. This is a built in event scheduler rather like CRON in Linux.
You can specify it to call a procedure, procedures or functions or run a bit of SQL at designated intervals.
Read the MySQL docs but an example would be:
CREATE EVENT mydatabase.myevent
ON SCHEDULE EVERY 1 WEEK STARTS CURRENT_TIMESTAMP + INTERVAL 10 MINUTE
DO
call clean_tables();
So this is saying "call clean_tables() once a week and make the first call in 10 minutes' time"
One gotcha is that the event scheduler is (I think) disabled by default. To turn it on run:
SET GLOBAL event_scheduler = ON;
You can then run:
SHOW PROCESSLIST;
To see whether the event scheduler thread is running.
As for preserving your Table A ID column (if you must). I would keep the ID on Table_Archive as unique to that table i.e make it the primary key & auto_increment and then have a 'Original_TableA_ID' column in which to store the TableA ID. You can put a unique index on this if you want.
So Table_Archive would be like:
create table `Table_Archive` (
ID int unsigned primary key auto_increment, -- < primary key auto increment
tableAId unsigned int not null, -- < id column from TableA
stringValue varchar(100),
timestamp datetime,
UNIQUE KEY `archiveUidx1` (`tableAId`) -- < maintain uniqueness of TableA.ID column in Archive table
);
Nobody seems to have answered your original question "How do I change _now to be the date 3 days ago?". You do that using INTERVAL:
DELIMITER $
CREATE PROCEDURE clean_tables ()
BEGIN
BEGIN TRANSACTION;
DECLARE _now DATETIME;
SET _now := NOW();
INSERT
INTO Table_Archive
SELECT *
FROM TableA
WHERE timestamp < _now - interval 3 day;
FOR UPDATE;
DELETE
FROM TableA
WHERE timestamp < _now - interval 3 day;
COMMIT;
END$
DELIMITER ;
One final point is that you should consider creating an index on the timestamp column on TableA to improve the performance of you clean_tables() procedure.

Answer 2

You may need to have a look into cron jobs if you want that script/query to be executed automatically.
If you are using cpanel have a look into http://www.siteground.com/tutorials/cpanel/cron_jobs.htm

Answer 3

Adding to the best answer (imo) by Tom Mac regarding the event scheduler - be aware that when backing up the schema, you have to specify that you want the events backed up with it via the --events=TRUE flag.
If you're exporting manually in the workbench, the latest version has a checkbox on the main 'Export To Disk' tab - older versions hide it away in the Advanced Export Options tab.

Answer 4

It is possible, MySQL will execute query automatically at specific time using MySQL Event Scheduler. Check this link for more details.
https://dev.mysql.com/doc/refman/5.7/en/event-scheduler.html