#Mysql add column huge table code#

INSERT INTO new_table SELECT * FROM tableģ. However, with a big table with hundred of columns, it is more difficult. Make sure that you select the information into the new table in the same order as the fields are defined. To add a new column to an existing table, you use the ALTER TABLE ADD COLUMN. It keeps running for more than 2 hours and still not completed. ALTER TABLE maintable ADD COLUMN location varchar (256) The maintable contains > 2,000,000 rows. You can create the structure from the existing table, then modify the structure however you’d like, then select in the data. I was just trying to add a column called 'location' to a table (maintable) in a database. The ALTER TABLE statement is also used to add and drop various constraints on an existing table. The ALTER TABLE statement is used to add, delete, or modify columns in an existing table. Suppose you have a table with one million records and if you try to add 3 columns in it, then it will certainly copy the table 3 times, which means coping 3 million records.Ī faster way of adding columns is to create your own new table, then select all of the rows from the existing table into it. The ALTER TABLE statement is used to add, delete, or modify columns in an existing table.

#Mysql add column huge table code#

Push code to add a Database Layer between client(s) and the database 3.

ALTER statements makes a new temporary table, copies records from your existing table into the new table even if the data wouldn't strictly need to be copied, and then replaces the old table with the new table. Build the Alter script to copy rows into a new table (in clumps of rows) 2. MySQL's ALTER TABLE performance can become very frustrating with very large tables.