[mythtv-users] Is locking tables important when backing up mythconverg?

Yeechang Lee ylee at pobox.com
Sat Apr 7 02:33:46 UTC 2007


So I have this script
(<URL:http://www.gossamer-threads.com/lists/mythtv/users/247868#247868>)
that I run every two hours to back up mythconverg. As the earlier
message notes, during the 100 seconds or so the script runs my
frontend won't respond to commands. If I'm watching a recording at the
time the playback normally but I can't pause, stop, or do other
things. If I am not playing back a recording and try to start watching
one, the frontend hangs at the black screen (that normally appears for
a after a second or two before the video appears). In both cases, once
the script completes running, things resume as normal.

The mysqldump man page tells me that it by default runs with --opt,
which is the equivalent of

    --add-drop-table
    --add-locks
    --create-options
    --disable-keys
    --extended-insert
    --lock-tables
    --quick
    --set-charset

--lock-tables is what causes the fleeting frontend freezeup. Some
quick experimenting with running my script with the addition of
--skip-lock-tables verifies this.

So, what am I risking here, if anything, by backing up the system with
--skip-lock-tables? Even as a database dunce I know enough about the
concept of table locking to ensure data integrity, but does it really
matter for what is fundamentally a single-user (mythbackend) database?

-- 
Yeechang Lee <ylee at pobox.com> | +1 650 776 7763 | San Francisco CA US


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