Why Quarkus MDC numeric fields silently break OpenSearch queries — and how to fix it

If you're running Quarkus with JSON logging and shipping to OpenSearch, there's a non-obvious bug waiting for you: every numeric field you put in MDC arrives in OpenSearch as a string. This means queries like durationMs > 1000 silently return nothing. No error. No warning. Just wrong results. Here's why it happens and two ways to fix it. The problem Quarkus uses JBoss Log Manager under the hood. When you set MDC values: MDC . put ( "durationMs" , String . valueOf ( duration )); MDC . put ( "fund