You can specify explicit ALGORITHM=INSTANT LOCK=NONE parameters, and if an instant schema change isn't possible, MySQL will fail with an error instead of falling back to INPLACE or COPY. It's not a magical solution, it has limitations and side-effects - it can only be the last column, the table must not have a full text index, etc - but should help in many cases. If it's easy for you to create replicas, like if you're hosted at Amazon RDS, you may create a master-master replica, run the alter table there, let it get back in sync, and switch instances after finished.Īs others mentioned, MySQL 8.0 INNODB added support for instant column adds. If you don't use foreign keys and it's slow because you have a lot of indexes, it might be faster for you to create a copy of the table with the changes you need but no secondary indexes, populate it with the data, and create all indexes with a single alter table at the end. ![]() Backup your data first! This is the easiest solution, but may not work in all cases. You may use the pt-online-schema-change, from Percona toolkit. It doesn't matter if it's slow, it only matters that other clients can't perform queries until your ALTER TABLE is finished. pt-online-schema-change can do the task with virtually zero lock time. ![]() (There would still need to be the UPDATE. Long answer: your real problem isn't really performance, but the lock time. This gets rid of one of the ALTERs: ALTER TABLE myTable ADD COLUMN basePrice FLOAT (10,2) NOT NULL DEFAULT 0 UPDATE myTable set basePrice 0,9 price MySQL 8.0 can add a column essentially instantly. We will again execute the DESC saledetails. CALL addColumnToTable () is executed whenever we want to run the procedure addColumnToTable. ALTER TABLE statement will ADD the new column to the table. Comments are attached to a column using the comment statement: create table sessionlog ( userid int not null, phonenumber int ) comment on column erid is The user ID comment on column sessionlog. ![]() In case the IF condition is not true, the statement after THEN is executed. You may add ENUM and SET values instantly, and you may add secondary indexes while locking only for writes, but altering table structure always requires a table copy. Database () function retrieves the current schema from the MySQL server. Are there other ways to improve performance of adding a column to a large table? Is there a way to add a new column and set its default value in MySQL When I run this command I get a syntax error: ALTER TABLE tableName ADD newColumn varchar (20) SET DEFAULT 'test' The documentation I've found doesn't really help me.
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