How use the gh-ost to transfer part of data from old table to new structure table ？

[zeusYi]

I want to modify a big table primary key from int to bigint ,but just want to migrate part of data just like " where id >= 1000000". Does gh-ost have the option like 'where' or 'filter' when migrate data ?

[shlomi-noach]

There is no such option. The entire table needs to be migrated.

[zeusYi]

All the table rows must be migrated ? I just want to migrated part of rows .

[tomkrouper]

gh-ost doesn't have a mechanism for partial migrations. Percona's pt-archiver might work for what you are wanting, but gh-ost will not.

[ggunson]

At GitHub if we want to do this we use both pt-archiver and gh-ost. We first delete the rows we no longer need with pt-archiver, and then we use gh-ost to migrate the smaller table.

[zeusYi]

@ggunson you konw the pt-archiver delete rows very very slowly.

[tomkrouper]

@yiwenshuo, the idea behind deleting rows slow is because it doesn't want to cause replication delays.

If having a --where clause in gh-ost is something you think it needs, we love PR contributions. I'm gonna go ahead and close this issue for now.