I use validation for my JDBC pool. I found that some requests took little bit more. After some investigation - I found more than 1 validation select per request. Sometimes I found 5-15 `select sysdate from dual` per request. I didn't find any error about JDBC validation in logs.
I use oracle database and validation class `org.glassfish.api.jdbc.validation.OracleConnectionValidation`. Validation is enabled, Validate At Most Once: 30s, pooling yes. min and max connection - 50.
My expectation about validation of JDBC connections was to see most once validation select per request.
I attached screenshot from elastic APM, one example of request, where payara did more validation per request.
Did I understand correctly? What can cause many validation selects per request?