Employee ADD DoNotCall bit not null Constraint DoNotCallDefault DEFAULT 0 and it will run extremely fast and use essentially no log space. There are other schema migration tools that use triggers, gh-ost has quite a few advantages over them though. If you are on SQL 2012, you can do that ALTER command, ALTER TABLE dbo.
With this huge amount of data I'd recommend cleaning up either the table or the data structure you use (a good DBA comes handy). This way no table 'properties' will be forgotten to add (including CHARSET or COLLATE). Haven’t used it much personally but it works for their schemas with billions to trillions of rows. You can right-click a table and select 'Send to SQL Editor' -> 'Create Statement'. It keeps them synced and only does the switch whenever you say so. It basically acts as a replica (from the bin logs) to set up your ghost table and get it synced with the old table, then does some validation steps to make sure all the data is copied over. If you really want to do it the right way, check out GitHub’s gh-ost tool which is designed for just these things. Create new table with the new schema, insert data from the old table, then quickly lock-> rename old table -> rename new table to old name -> unlock Are there other ways to improve performance of adding a column to a large table Short answer: no. If you need to maintain active connections for a slow operation, the common way is with a ghost table. If there’s a time when you can temporarily boot all connections, that can speed it up significantly too. Locking the table before altering will speed it up but that’s not always possible.
#MYSQL ADD COLUMN HUGE TABLE CODE#
I wouldn’t expect adding a column to be all that slow even with a few million rows, does some connection have a write lock or something? Of course, things like indexes, defaults, wide rows, many connections, and a slow/overworked server will slow things down. To add a new column to an existing table, you use the ALTER TABLE ADD COLUMN statement as follows: ALTER TABLE table ADD COLUMN columnname columndefinition FIRST AFTER existingcolumn Code language: SQL (Structured Query Language) (sql) Let’s examine the statement in more detail. 1 Two occurrences could cause such a delay - being blocked (probably repeatedly, up to RowCount times) by simultaneous table updates, or having to rebalance indices RowCount times.
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