Strategy for supporting large message folders

David Bienvenu mozilla at davidbienvenu.org
Thu Jan 17 23:17:31 UTC 2013


On 01/17/2013 03:05 PM, Kent James wrote:
> On 1/17/2013 11:54 AM, David Bienvenu wrote:
>> msgKey is used as a key in the nsIMsgDatabase to get the msg hdr for 
>> a particular key, so yes, it's still used in all sorts of places in 
>> the code, but should not be used as the offset into the berkeley 
>> mailbox. If it were, maildir support would not work at all, instead 
>> of only kinda working.
> The key is not used as the offset into the berkeley mailbox, but isn't 
> the offset used to generate the key,
Only if the offset is well less than 4GB. If it's approaching 4GB, then 
we just start assigning keys one by one, as available, and lose 
backwards compatibility of .msf files with pre-pluggable store versions 
of TB. Iirc, we save the last million 32 bit keys for assigning message 
keys to messages with offsets > 4GB. So we've replace the 4GB limit with 
a limit of a million messages per folder (plus however many messages fit 
in the first 4GB).

Since pluggable stores have been out for a while, perhaps we don't care 
so much about backwards compatibility, and can just dole out keys one by 
one. You should be able to change the code that picks messages keys when 
adding new messages w/o bothering versions of TB with pluggable store 
turned on.

- David




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