Expected behavior for Upgrade Assistant 7.0 to show automatic field expansion warning even after changing max_clause_count?

[slmingol (Sam Mingo)]

We're in the middle of upgrading from ES 6.8 to 7.1 and are trying to address guidances regarding 7.0 Upgrade Assistant. The Assistant is calling out the following issues on several indicies:

This index has [1178] fields, which exceeds the automatic field expansion limit of 1024 and does not have [index.query.default_field] set, which may cause queries which use automatic field expansion, such as query_string, simple_query_string, and multi_match to fail if fields are not explicitly specified in the query.

We've attempted to address this issue by changing this setting:

$ showcfg_cluster l | grep max_clau
    "indices.query.bool.max_clause_count" : "3072",

But the error/warning still remains. I found this other question which leads one to believe that the continued display of the msg is normal and the issue has been resolved by overriding the max_clause_count but we'd like additional reassurances before proceeding.

[slmingol (Sam Mingo)]

I figured out that we can simply do the following to address the upgrade assistant warnings.

• Add default_field: [ "*" ] to each index's _settings.

And override "indices.query.bool.max_clause_count" with a large enough number to handle our number of fields. For eg.

"indices.query.bool.max_clause_count" : "3072",