> On 04/07/11 11:00, Vlad Khorsun wrote:
>> Right after CREATE DATABASE and until disconnect database works with
>> actual FW=OFF,
>> despite of settings on header page. We specially didn't changed this to make
>> restore fast and
>> simple (no need to disconnect and no chance to lose exclusive attachment).
>
> Always thought that this works only for gbak attachment. What do you
Hmm... i was wrong about gbak. It is explicitly set isc_dpb_force_write to
0 when created database.
Later, after restore of data, it restored also FW flag to the state which was
read in backup file.
> think, is it a bug or a feature in non-gbak case?
So, i think, this is the bug. Look at jrd8_create_database, it :
a) create database using PIO_create(). PIO_create() creates file in FW=OFF mode.
b) format header page using PAG_format_header(). It set FW=ON flag on header
page.
Note, current file is opened with FW=OFF mode and fil_flags have no
FIL_force_write flag set
c) then it call PAG_set_force_write(), if isc_dpb_force_write was set in DPB
- if isc_dpb_force_write is present in DPB and set to zero then FW=OFF will
be set at header
page and file will not be re-opened with FW=OFF as it is already in this
mode
- if isc_dpb_force_write is present in DPB and set to non-zero value then
FW=ON will be set
at header page and file will be re-opened with FW=ON
- if isc_dpb_force_write is NOT present in DPB nothing will be done and
file will be left in
FW=OFF mode while header page will sill have FW=ON flag. So, next
attachment will
work in correct FW=ON mode.
We can fix engine (make PIO_create to create files in FW=ON mode, or add
new parameter to it) but
we can't fix old applications which creates database and expect fast work in
this first attachment.
Regards,
Vlad
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