Solr FTS - message deletes not working as expected

[Michael Slusarz]

> On 11/03/2021 12:56 PM Shawn Heisey <elyograg at elyograg.org> wrote:
> 
> > Thunderbird does NOT necessarily process expunges immediately.  Depends on what else it is doing in the background.  So you can't click delete in the UI and not immediately see anything on the backend and definitively correlate the two.
> 
> The message is deleted by dovecot immediately.  I double checked this by 
> purging a message on my Linux client and saw the message immediately 
> disappear on my Windows client.  It happened even faster than I would 
> have expected.  IMAP seems to be a very good protocol!  I can't say it 
> definitively without more evidence, but the problem *seems* to be in 
> FTS, not imap or core dovecot.

For Solr, there's a code path in the FTS expunge code that will silently toss expunge requests:

        if (ctx->last_indexed_uid == 0 ||
            uid > ctx->last_indexed_uid + 100) {
                /* don't waste time asking Solr to expunge a message that is
                   highly unlikely to be indexed at this time. */
                return;
        }

So it's possible you are running into that.

michael