Re: Re: [firebird-support] Update big table and nbackup benefit or not?

2016-04-05 Thread liviuslivius liviusliv...@poczta.onet.pl [firebird-support] 


W dniu 2016-04-05 12:45:34 użytkownik Dimitry Sibiryakov s...@ibphoenix.com 
[firebird-support]  napisał:
> 05.04.2016 12:43, liviuslivius liviusliv...@poczta.onet.pl [firebird-support] 
> wrote:
> > but what happens at merge stage (delta merging) when i unlock database?
> > page will be overriden or new one will be created and old will be marked as 
> > empty?
> 
>Old pages will be overwritten, new ones will be added. No difference.
> 
> -- 
>WBR, SD.
> 


Ok now i understand how delta work 
then i see that only benefit will be when page have some free space 
but this make no difference in both scenarios 1 and 2

thanks for the info


regards,
Karol Bieniaszewski

Re: [firebird-support] Update big table and nbackup benefit or not?

2016-04-05 Thread Dimitry Sibiryakov s...@ibphoenix.com [firebird-support] 
05.04.2016 12:43, liviuslivius liviusliv...@poczta.onet.pl [firebird-support] 
wrote:
> but what happens at merge stage (delta merging) when i unlock database?
> page will be overriden or new one will be created and old will be marked as 
> empty?

   Old pages will be overwritten, new ones will be added. No difference.

-- 
   WBR, SD.






++

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++


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Re: [firebird-support] Update big table and nbackup benefit or not?

2016-04-05 Thread Dimitry Sibiryakov s...@ibphoenix.com [firebird-support] 
05.04.2016 10:21, liviuslivius liviusliv...@poczta.onet.pl [firebird-support] 
wrote:
> what is the answer for this A or B?

   None of them. Full pages are written to delta file, so you'll have database 
in exactly 
the same state as per scenario 1.

-- 
   WBR, SD.






++

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Re: Re: [firebird-support] Update big table and nbackup benefit or not?

2016-04-05 Thread liviuslivius liviusliv...@poczta.onet.pl [firebird-support] 
Hi,
 
thanks Tim for warning - i know fragmenting records are bad
but in my case this probably not happen because this is ppmxl database with 
numbers only 
 
but do you know what will be answer A or B?
If no one answers I'll have to test yourself ;-)
 
regards,
Karol Bieniaszewski
 
 
If the update makes the records longer (after run-length encoding) it's even 
more fun, as you might get fragmentation (of records across pages) and access 
times can then increase by a very large factor indeed, even to the extent of 
completely crippling the performance of an entire application.
On 05/04/2016 09:21, liviuslivius liviusliv...@poczta.onet.pl 
[firebird-support] wrote:
 
Hi,
 
i must update big table 100 GB
and as we know when we do update then new record version will be created.
scenarion 1:
 
1. Table size 100GB (db size 200GB)
2. Update field in all records generate 100GB new record versions
3. table size after is 200GB (db size 300GB)
4. sweep remove 100GB and mark pages as free (table size 100 GB but database 
still 300GB)
5. backup and restre bring db to it previous size (db size 200GB)
 
but what happen when i do this?
 
scenarion 2:
1. Table size 100GB (db size 200GB)
2. i lock database with nbackup -L 
3. Update field in all records generate 100GB delta file (db size 200GB)
4. table size in db is 100GB and delta is 100GB (db size 200GB)
5. i unlock database nbackup -U
 
A. table will be 100GB and no free pages? (db size will be 200GB and no need to 
bacup and restore process)
B. table will be 100GB and in db will be 100GB free pages? (db size will be 
300GB and i need to bakup and restore?)
 
what is the answer for this A or B?
 
regards,
Karol Bieniaszewski
 
-- Tim Ward
__._,_.__

 

Re: [firebird-support] Update big table and nbackup benefit or not?

2016-04-05 Thread Tim Ward t...@telensa.com [firebird-support] 
If the update makes the records longer (after run-length encoding) it's 
even more fun, as you might get fragmentation (of records across pages) 
and access times can then increase by a very large factor indeed, even 
to the extent of completely crippling the performance of an entire 
application.


On 05/04/2016 09:21, liviuslivius liviusliv...@poczta.onet.pl 
[firebird-support] wrote:

Hi,
i must update big table 100 GB
and as we know when we do update then new record version will be created.
scenarion 1:
1. Table size 100GB (db size 200GB)
2. Update field in all records generate 100GB new record versions
3. table size after is 200GB (db size 300GB)
4. sweep remove 100GB and mark pages as free (table size 100 GB but 
database still 300GB)

5. backup and restre bring db to it previous size (db size 200GB)
but what happen when i do this?
scenarion 2:
1. Table size 100GB (db size 200GB)
2. i lock database with nbackup -L
3. Update field in all records generate 100GB delta file (db size 200GB)
4. table size in db is 100GB and delta is 100GB (db size 200GB)
5. i unlock database nbackup -U
A. table will be 100GB and no free pages? (db size will be 200GB and 
no need to bacup and restore process)
B. table will be 100GB and in db will be 100GB free pages? (db size 
will be 300GB and i need to bakup and restore?)

what is the answer for this A or B?
regards,
Karol Bieniaszewski




--
Tim Ward

[firebird-support] Update big table and nbackup benefit or not?

2016-04-05 Thread liviuslivius liviusliv...@poczta.onet.pl [firebird-support] 
Hi,
 
i must update big table 100 GB
and as we know when we do update then new record version will be created.
scenarion 1:
 
1. Table size 100GB (db size 200GB)
2. Update field in all records generate 100GB new record versions
3. table size after is 200GB (db size 300GB)
4. sweep remove 100GB and mark pages as free (table size 100 GB but database 
still 300GB)
5. backup and restre bring db to it previous size (db size 200GB)
 
but what happen when i do this?
 
scenarion 2:
1. Table size 100GB (db size 200GB)
2. i lock database with nbackup -L 
3. Update field in all records generate 100GB delta file (db size 200GB)
4. table size in db is 100GB and delta is 100GB (db size 200GB)
5. i unlock database nbackup -U
 
A. table will be 100GB and no free pages? (db size will be 200GB and no need to 
bacup and restore process)
B. table will be 100GB and in db will be 100GB free pages? (db size will be 
300GB and i need to bakup and restore?)
 
what is the answer for this A or B?
 
regards,
Karol Bieniaszewski