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Re: Examples of savepoints and transactions




What you're looking for is simple backup and restore :-)

Savepoints are, simply put, markers within a transaction; allowing you to rollback only part of a transaction instead of the whole thing. A commit will inevitably commit the ENTIRE transactions, and thus remove the savepoints.

A typical workflow for the kind of thing you're trying to do is to have your (automated) testing framework restore last night's backup after the test run. You could also make a backup before the test run and restore that afterwards; have an automated nightly db copy from prod to dev; or in very specific cases you could simply have your test system revert the data by issuing the "reverse" queries - although that one is rarely an option in real life.

Another alternative would be to take a filesystem (or virtual machine) snapshot, and revert to that after the tests. Filesystem snapshots will require your database to be stopped and started, though.

/Johan


----- Original Message -----
> From: "Lars Nielsen" <lars@xxxxxxxx>
> To: "MySql" <mysql@xxxxxxxxxxxxxxx>
> Sent: Tuesday, 23 January, 2018 23:19:29
> Subject: Re: Examples of savepoints and transactions

> Den 22-01-2018 kl. 22:01 skrev shawn l.green:
>> Hello Lars,
>>
>> On 1/21/2018 3:37 PM, Lars Nielsen wrote:
>>> Hi,
>>> I have a system that uses begin and commit transactions. It works
>>> like a dream! ;)
>>> Now I want to test it by creating test data. This how ever cannot be
>>> rolled back. I think the solution for rolling back test data is to
>>> use savepoints and rollback. I think it is hard to find examples of
>>> this scenario. Are there some good guides or tutorials out there
>>> somewhere? Any suggestions are welcome.
>>>
>>> Best regards
>>> Lars Nielsen
>>>
>>
>> Can you mock up an example (a simple text walkthrough) of how you
>> think a savepoint should work with what you are calling "test data" ?
>> I think that the term "test data" is too general to make much sense to
>> most of us in the context you described.
>>
>>
>> Yours,
> Hello Shawn,
> Thanks for your interest. Here is an example of my idea.
> 
> I have a php site working through PDO connections. I insert some data
> through php like this :
> 
>|START TRANSACTION; SELECT @A:=SUM(salary) FROM table1 WHERE type=1;
> UPDATE table2 SET summary=@A WHERE type=1; INSERT INTO table3 values (x,
> y, z); COMMIT; |||
> 
>||Now I want to do automated tests that create "dummy" data that i want
> to remove after the test has finished:
> like this :
> 
>|SAVEPOINT autotest1; START TRANSACTION; SELECT @A:=SUM(salary) FROM
> table1 WHERE type=1; UPDATE table2 SET summary=@A WHERE type=1; INSERT
> INTO table3 values (x, y, z); COMMIT; -- DO OTHER TRANSACTIONAL
> OPERATIONS.... ROLLBACK TO autotest1; |||
> 
>||All done. I have tested the application and have cleaned up the dummy
> test-data.
> 
> The issue is that when I call the first commit then the savepoint is
> deleted.
> 
> Is this possible at all?
> 
> Regards Lars
> 
>||
> 

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