Sql updating table definition
Also, in a transaction when updating row by row with a large volume, it might be possible that deadlocks occur because row iteration in the transaction takes more time.I am going to update the Cust Transaction table with one command.I have prepared the sample query and executed as follows. It’s a faster update than a row by row operation, but this is best used when updating limited rows.A bulk update is an expensive operation in terms of query cost, because it takes more resources for the single update operation.Updating row by row is very slow, but less resource intensive and the consistency is at a statement level.If you want all updates to be consistent for the table, you would need to use a transaction, because if one update fails, the rest will succeed.UPDATE TABLENAME SET COLUMNNAME = Other Alias.column Name FROM TABLENAME AS Alias INNER JOIN OTHERTABLE AS Other Alias ON Alias.column Name = Other Alias.column Name WHERE Other Alias.column Name = (Some Value) We need to aware of these difference methods. Is there some performance impact due to infrastructure, isolation level, concurrent processes that are running, etc.I am going to update the table Cust Transaction using a row by row method with a loop.
(Bug #11758262, Bug #50439) See Section 184.108.40.206, “Determination of Safe and Unsafe Statements in Binary Logging”, for more information.Modify Column Syntax Sometimes we need to change the data type of a column.To do this, we use the ALTER TABLE Modify Column command.Another approach is to update the data in smaller batches.
So instead of doing row by row updates or one big update, I have divided the data into batches of 10K rows and performed the update operation as shown below.I prefer to update data in batches for large volumes of data.