Did the following:
* backed up a 3.0.12 site containing 1.200.000 posts and copied it 1:1 to 2nd webserver. Site configured for "phpBB Native Fulltext" search
* ran upgrade procedure --> 3.2.1
Found that after upgrade the search method had been changed to one of the other 3 available options (can't remember which one).
The moment I changed search method back to "phpBB Native Fulltext", ACP tells me to rebuild search index. It probably deleted the index beforehand but I'm not sure as I didn't check the contents of table phpbb_search_wordmatch.
Instead I went to Maintenance -> Search Index and clicked "Create index" button in phpBB Native Fulltext section.
After 3 days it hat indexed all posts and created roughly 42.000.000 rows in phpbb_search_wordmatch.
BUT!
The real problem here is that the process constantly timed out / halted / was interrupted... whatever.
Status page would display for some time, and at some point go blank.
I could watch rowcount in phpbb_search_wordmatch increasing and shortly after status page went blank the rowcount stopped increasing.
I could then refresh the status page by hitting F5 and then it would again run for a random time. Sometimes half an hour, sometimes 2 minutes.
I'm dead serious when I say I restarted it at least 500 times.
The good thing is that the process picks up where it left.
It says something like "800.000 posts out of total 1.200.000 have now been indexed". It increases by between 100 and 500 every minute or so...
I read a ton of support threads that mention this issue and tried different suggestions:
* decommented a line in functions.php as suggested in this thread: viewtopic.php?f=46&t=1814575
* installed Chrome plugin that automatically refreshes page at configurable intervals --> no difference; timed out and stopped anyways
... all to no avail.
What is the problem here?
Is there any way to have the index rebuild process not interrupt/break itself so that it can run continuously without supervision ?
I can easily live with rebuilding an index even if it takes a day or two to complete - if it would only run without needing a babysitter.