[GitHub] davisp commented on a change in pull request #1201: This fixes couch_bt_engine:fold_local_docs/4

[GitBox <gi...@apache.org>]

davisp commented on a change in pull request #1201: This fixes couch_bt_engine:fold_local_docs/4
URL: https://github.com/apache/couchdb/pull/1201#discussion_r172037448
 
 

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 File path: src/couch/src/couch_bt_engine.erl
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 @@ -464,7 +464,10 @@ fold_docs(St, UserFun, UserAcc, Options) ->
 
 
 fold_local_docs(St, UserFun, UserAcc, Options) ->
-    fold_docs_int(St, St#st.local_tree, UserFun, UserAcc, Options).
+    case fold_docs_int(St, St#st.local_tree, UserFun, UserAcc, Options) of
+        {ok, _Reds, FinalAcc} -> {ok, null, FinalAcc};
 
 Review comment:
   Good call. Its actually higher up when its expected to be null in fabric. What happens is that depending on what shards have actual docs you get a combination of null and 0 which leads to badarith exceptions when trying to do `0 + null` basically.
   
   This is definitely a bit of a sharp corner on PSE vs features that assume legacy engine behavior. But for v1 its mostly a game of trying to define existing behavior so that we can refine what's expected/acceptable for future engines.

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