6
votes
2answers
204 views

Is there any way to trace optimizer's work in MySQL?

Just like the MEMO structure in SQL Server which is kind of a "paper trail" of steps the optimizer takes in optimizing the query. Is there anything in MySQL through which I can get the information ...
-3
votes
1answer
83 views

want to optimize this query by removing two SELECT and two JOINS

SELECT t3.transaction_pci_details_id, t3.terminal_id, t3.transaction_no, t4.transaction_id, t3.transaction_type, t3.reversal_flag, t3.transmission_date_time, t4.retrivel_ref_no, t3.card_no, ...
28
votes
3answers
2k views

Unexpected scans during delete operation using WHERE IN

I've got a query like the following: DELETE FROM tblFEStatsBrowsers WHERE BrowserID NOT IN ( SELECT DISTINCT BrowserID FROM tblFEStatsPaperHits WITH (NOLOCK) WHERE BrowserID IS NOT NULL ) ...