Saturday, 16 November 2013

Inno DB roww level locking

I was hearing the term row level locking for a very long time. But I really don't know  whats that and TBH i don't even tried to know what it could be.

Nov 14 got a mail from my application Manager. Its starts with Hi Senthil " Please look in to this and Advice". I have replied to that Email saying I've asked for logs from sys-admins.

Got the logs and found that 1 Order number assigned to 2 Customer @ the same time. So now I got the issue.

Yeah I caught your mind voice. Exactly googled .... Got the solution is lock the row.

Then I started thinking how. Don't worry its easy.

i) Change your table engine to INNODB.
ii) Add transaction before start selecting the order number from the number. ( You need to have the running order number in a table, so that you can simply access it )
iii) Select query needs to be like the below

SELECT order_number_column from table_name where blah blah ..... for UPDATE;

for update will lock the row, so even on high traffice the order number will be unique.

iv) Dont forget to commit ( if success) or rollback ( if error only on error condition ) else you will end up in dead lock.

Hope you got some idea about row level locking and the use case. 

Tuesday, 26 March 2013

Funny Typo Errors in Magento EE 1.12

Few Day back i came across an issue in Magento Admin. Though its not a potentially a great functionality bug, i dig in to that because of our great testing team and ended up with funny typo error.

I though its the bug only in Magento EE 1.12, unfortunately :) its there in all the version and in multiple place. Ok Now coming to the issue.

"Success Message is not clearing even after i update something".

Lets say i am applying a promo which gives me success message or let say i am getting some error message in header, even after rectifying that error in cart it remains the same. Means the Error message not cleared.

Problem is because of

 if(this.loadingAreas.indexOf('message'==-1)) this.loadingAreas.push('message');

Refer the indexOf function above which is there in "js/mage/adminhtml/sales.js". It should be  if(this.loadingAreas.indexOf('message')==-1)"[" + name[1] + "]") != -1 && messages[i].value != "") -- Line 821

area.indexOf('items' != -1) -- Line 853

I though it was actidental but it seems like intentional :) .... but any way we have to correct  if you are facing any funniest problem like this in Magento Admin hope you got some idea to dig further......