16816 - rows with 0 ref-count should be removed from databases

Status: VERIFIED FIXED

(MailNews Core :: Database, defect, P3)

Description

[David :Bienvenu]

Rows with a 0 ref-count should be removed from databases. Otherwise, mail
folders will grow monotenously, especially the inbox :-)

Comment 1

[davidmc]

During a compress commit, when iterating over all rows in a rowspace, I should
not write rows with a zero persistent refcont (mRow_GcUses), because this would
mean a row is not referenced by any table or cell.  I must review the code that
maintains mRow_GcUses for correctness, and I should add asserts that rows in
tables have zero refcounts.  We might want another bug for collecting empty
tables with zero refcounts, since otherwise empty thread tables will never go
away either.  Or else we can use this bug as the generalized bug to fix garbage
collection of unreferenced peristent objects with IDs in Mork files.

Comment 2

[Phil Peterson]

David or David, do you think we need to fix this for B1? My intuition is not, so
I'm marking M15, but let me know if you disagree.

Comment 3

[davidmc]

While not necessary, it's very easy.  So I'll plan to squeeze it in with some
flushing of code from my local tree in January.

Comment 4

[David :Bienvenu]

these are mine now, I guess.

Comment 5

[David :Bienvenu]

fix checked in - to verify, you can take a local folder with 1000 messages, look 
at the size of the .msf file, delete all the messages, shut down, and look at 
the size of the msf file again. The size should be a lot smaller. In theory, it 
should go down to close to 0, but it doesn't quite. I haven't looked to see why 
yet, but the size does go way down.

Comment 6

[fenella]

Win 32 (2000-06-14-08 M17)
I re-tested it as instructed.  Using a local folder with 1006 message, after
deleting, shut down, the msf file is reduced from 329 KB to 55 Kb.  I supposed
this is working as expected.

Comment 7

[David :Bienvenu]

yes, good enough. you can mark it verified. thanks.

Comment 8

[fenella]

sure.