Define a new option for DROP SHADOW command to leasve the shadow file in the
filesystem
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Key: CORE-4955
URL: http://tracker.firebirdsql.org/browse/CORE-4955
Project: Firebird Core
Issue Type: Improvement
Affects Versions: 3.0 Beta 2, 2.5.4
Environment: all
Reporter: Holger Klemt
We have very good experience with using shadows as as much faster backup
alternative.
Up to fb25 we can do some changes on RDB$FILES to avoid the filedelete, that is
doen automaticaly when using DROP SHADOW.
It would be a very good feature for Firebird 2.x but at least for fb3, when we
can use the DROP SHADOW command with an additional
new option, that does not drop the shadow file from the filesystem.
We use this way esepcially in combination with RAM Disk to create and drop a
shadow. Since the shadow file can
be used as a database directly, we save a lot of time compared to a full
backup/restore process and based on our
current way with changes in RDB$FILES, which will not work in FB3, we and our
customers would really like to have
such a new option.
And yes, we know, that a shadow does no reorg etc., but here are some numbers i
showed a customer yesterday
on my laptop (all operations were done on a 240 GB enterprise SSD in a i7
Laptop with 8GB RAM, Customer database
was 1.6 GB, almost no blobs, but a lot of records and a lot of indices)
Backup using gbak fb254 win64: 65 seconds
Restore using gbak fb254 win64: 410 seconds
overall around 8 minutes
and now using a script in ibexpert using a ramdisk and a shadow
-create shadow
-commit;
-update rdb$files
-commit
-drop Shadow
-commit
overall around 8 seconds!
Really, the whole script used 8 seconds! The customer was extremly impressed,
especially since they
control very large machines using their software and firebird
We use the same way with database up to 10 GB and there we have a typical time
of 30 seconds
This makes it possible for the customer to start the shadow based
backup/restore replacement job every 30
minutes, since it only uses 30 seconds of high load. After creating the shadow
on the ramdisk and dropping it,
it is copied to their backup server.
I think such an additional option for drop shadow statement should not be a bug
deal for the core developers
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