Flush logs and lock tables order

[IB Development Team]

Hi,

In

http://bazaar.launchpad.net/~lenzgr/mylvmbackup/trunk/view/head:/mylvmbackup.pl.in

flushing binary log is done in "preflush" before locking tables "flush_tables":

  run_hook ("preflush");
  flush_tables($dbh) unless ($skip_flush_tables == 1);

  create_posfile($dbh);

  run_hook ("presnapshot");
  $snapshot_created= create_lvm_snapshot();

Why not to flush logs ("preflush") after tables are locked ("flush_tables") and have posfile to point to the beginning of next binlog file? We can see this (correct?) order on

http://dba.stackexchange.com/questions/116816/flush-tables-with-read-lock-not-working
http://www.daork.net/archives/4

Now it is possible to have some changes recorded in new binlog file between preflush and flush_tables which probably is less elegant/problematic?

One more thing; in

http://bazaar.launchpad.net/~lenzgr/mylvmbackup/trunk/view/head:/man/mylvmbackup.pod

there is

"
If you use InnoDB tables exclusively, you may also want to consider to include
the option I<--skip_flush_tables>, to avoid the probably time-consuming and in
this case unnecessary flushing of buffers.
"

but using this option does not stop database InnoDB write activity probably and binlog may change between pos file creation and lvm snap which may be a problem?

Please verify and fix.

Regards,
Pawel

IB Development Team
https://dev.ib.pl/