[Nate]

We have about 23k topics, so maybe that’s the issue. If it is, is there a fix?

This is what happens when I attempt to merge topics:

Merge with this topic: 
Fatal error: Allowed memory size of 67108864 bytes exhausted 
(tried to allocate 35 bytes) in /home/content/37/9672937/html/wp-includes/wp-db.php on line 1228

[Stephen Edgar]

It should work, though your issue is more of a memory issue that may involve getting this checked out by your web hosting provider.

How big are the two topics you are trying to merge, i.e. how many replies are in each topic?

[Nate]

@netweb … the topics are fairly small, maybe 6-8 posts apiece.

One thing that I noticed a few months ago when merging is that, from the list of available topics to ‘merge’ into, it displayed *ALL* topics in a dropdown list. I have to believe that’s where the issue is coming into play. Maybe it’s the hosting provider, but even so, navigating hundreds of topics didn’t seem optimal.

Now that you’re officially on the dev side, I have a suggestion: we left the Scout.com forums (proprietary – they developed everything in-house) and the merge feature happened at the forum level with a checkbox beside each topic — so mods could batch delete topics; select 2 (or more) topics and merge them into one; they could also move the topic to a different forum.

Just an idea.

[Stephen Edgar]

That sounds like a performance issue indeed having a dropbox with ‘all’ those topics, I just tried it here on bbpress.org and it isn’t an issue, presumably this is due to the difference in host setups. 😉

If you can create a ticket in Trac https://bbpress.trac.wordpress.org/ we can look at making some performance improvements, what exactly can be done in what timeframe I do not know.

Can you bump your PHP Memory on your web host from 64MB -> 128MB until you get all your merges complete is propably the only quick fix I can think of off the top of my head right now.