Enhance performance of update query I have a query that is running against a table with 50 million rows.  The phone number is stored as a CHAR(10) and an ETL process is changing the phone number if it has certain values.  We are seeing poor performance of this query and was wondering if anyone has any suggestions on improving performance.  No index currently exists with the phone number.

UPDATE Table SET phone='' WHERE ( phone IS NULL
              OR phone = ''
              OR phone = '0000000000' 
              OR phone = '0' 
              OR phone like '111%'
              OR phone like '222%'
              OR phone like '333%'
              OR phone like '444%'
              OR phone like '555%'
              OR phone like '666%'
              OR phone like '777%'
              OR phone like '888%'
              OR phone like '999%'
              OR phone like '800%'
              OR phone like '900%' 
            )
It depends on what you mean by improve performance.  You can't make that query faster, it needs to scan the table.  But you can keep it from using too many resources and blocking other processes by chunking it, which is essentially iterating through batches of  rows to perform multiple smaller updates.  

There must be some option to just write it to the target table instead of updating in place.  

You could also forego the scrub altogether and use a non-persisted computed column in the target database to reformat the phone number if you don't need to index it.