Re: Transaction commit speed

[Howard Chu <hyc@symas.com>]

Sam Dave wrote:
> Hi,
> 
> Are transaction commits always fast (almost instantaneous) operations compared to the read or write operations within it? Is it possible for say an
> mdb_cursor_get or mdb_put to be faster than a subsequent mdb_txn_commit, and if so under what circumstances can that happen?
> 
> 
> This is relevant info for UI applications showing a progress indicator. If an mdb_txn_commit is always fast, we can rely on the _get/_put count to calculate the
> percentage.

Generally no, a txn_commit should take time proportional to the number of pages that
were dirtied in the transaction. And that number depends on the number of puts/dels
that were performed in the transaction.

gets don't dirty any pages, so they are irrelevant for commit speed.
-- 
  -- Howard Chu
  CTO, Symas Corp.           http://www.symas.com
  Director, Highland Sun     http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP  http://www.openldap.org/project/