keys quey does not work in partitioned DB

[mhsadri007]

Description

Hi, I'm using CouchDB 3.1.1 to store both partitioned and non-partitioned data in separate databases. When querying a custom view with key parameter, CouchDB works perfectly on both databases but when I try to use keys instead of key to query a reduce view on partitioned database, I get the following response (assuming the special characters in URL are escaped perfectly or a web browser (FF) used to query the DB)

Steps to Reproduce

curl http:https://admin:[email protected]:5984/PartitionedDB/_partition/user01/_design/folder_count/_view/folder_count?keys=["0","2"]&group=true
{"rows":[]}

curl http:https://admin:[email protected]:5984/PartitionedDB/_partition/user01/_design/folder_count/_view/folder_count?key="0"
{"rows":[ {"key":null,"value":3} ]}

While that view is not empty:

curl http:https://admin:[email protected]:5984/PartitionedDB/_partition/user01/_design/folder_count/_view/folder_count?group=true
{"rows":[
{"key":"0","value":3},
{"key":"1","value":12},
{"key":"2","value":1},
{"key":"3","value":3},
{"key":"31","value":1},
{"key":"311","value":3}
]}

Expected Behaviour

Should display the result as the multiple keys query parameter does in non-partitioned DB

Your Environment

OS: Windows 7 64bit
CouchDB 3.1.1

curl http:https://127.0.0.1:5984
{"couchdb":"Welcome","version":"3.1.1","git_sha":"ce596c65d","uuid":"f89258d2cbb860f8181311e52dedc5fd","features":["access-ready","partitioned","pluggable-storage-engines","reshard","scheduler"],"vendor":{"name":"The Apache Software Foundation"}}

• CouchDB version used: 3.1.1
• Browser name and version: Firefox 81.0 64-bit
• Operating system and version: Windows 7 64-bit