Subject Re: [firebird-support] Blob storage mechnism
Author Lester Caine
b0bik2000 wrote:
> If I have large blob data in my BLOB field in DB - it is stored in "blob 2 level" manner. But what about changing data size (by updating this column) to something smaller - something that can fit "blob 0 level" - will FB change storage manner to "level 0" ? When will it happen - immediately or after backup restore ? What will happen with old blob data pages ?

Unused pages just get put back into the pool and reused. It may be that some
other open transaction may be retaining a view of a deleted BLOB in which case
the pages do not become 'garbage collected' until all interest in the past
history has been completed. The nice thing about Firebird is that there is no
need to worry ... spare space will get reused ...

Lester Caine - G8HFL
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