Question

I have LAMP server with fast storage and a lot of memory and processor power.

There are 2 tables with same structure, one with 30.000.000 records, other is empty.
I want to copy data from first table to second and use this request:

 INSERT INTO table2 SELECT * FROM table1 ;

This request need more then 4 hours to complete. I think this is not normal because mysqldump of entire database finishes less then hour.

Are there any limits to SELECT request? Or I must use other code to optimize performance?

Answer 1

Make sure the schema is as like as the first table, then give the order of values in Insert query. * lowers the performance of the Select query, And NoLock Increase the data availability

like,

Begin Tran
      INSERT INTO (Col1,Col2, Col3,...Coln) table2 
    SELECT (Col1,Col2, Col3,...Coln) FROM table1 with (NoLock)
Commit