Hello Geetanjali,
On 9/23/2014 7:14 AM, geetanjali mehra wrote:
Can anybody please mention the internals that works when we use mysqldump
as follows:
*mysqldump --single-transaction --all-databases > backup_sunday_1_PM.sql*
MySQL manual says:
This backup operation acquires a global read lock on all tables at the
beginning of the dump (using *FLUSH TABLES WITH READ LOCK
<http://dev.mysql.com/doc/refman/5.6/en/flush.html>*). As soon as this lock
has been acquired, the binary log coordinates are read and the lock is
released. If long updating statements are running when the FLUSH
<http://dev.mysql.com/doc/refman/5.6/en/flush.html> statement is issued,
the backup operation may stall until those statements finish. After that,
the dump becomes lock-free and does not disturb reads and writes on the
tables.
Can anyone explain it more? Please.
Which part would you like to address first?
I have a feeling it's more about how FLUSH TABLES WITH READ LOCK works
but I want to be certain before answering.
Yours,
--
Shawn Green
MySQL Senior Principal Technical Support Engineer
Oracle USA, Inc. - Hardware and Software, Engineered to Work Together.
Office: Blountville, TN
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