Subject Re: Best way to delete millions of rows
> ---In, <kragh.thomas@...> wrote :
> Hey Vlad
> If i only count the deleted rows, the problem is the same, and the server hangs while performing garbage collection.

  Sad. Probably, table have a lot of indices ? IO subsystem, amount of RAM, page size and page cache size also
matters. Also interesting if filesystem is mounted with "barrier=on" option

> On the other hand, if I count the rows not deleted, no garbage collection is performed - that makes sens as the index
> on created makes sure that no delete records/rows are accessed. This is useful to know as i can make sure that other
> parts of the application never issues a query for rows older that 6 months.

  It still will clean up record versions left after UPDATE's

> Now the garbage collection will be deferred and happen during backup. Is it possible that the same "hang" behavior will
> happen during backup as a result of the deferred garbage collection?

  gbak have no magic, it just reads the tables and put data into backup file.