ouyangwulin created FLINK-40144:
-----------------------------------
Summary: Avoid query database when only get table column
Key: FLINK-40144
URL: https://issues.apache.org/jira/browse/FLINK-40144
Project: Flink
Issue Type: Improvement
Components: Connectors / JDBC
Reporter: ouyangwulin
The {{SELECT *}} here doesn't actually read the table data yet, because the
code only calls:
‘
PreparedStatement ps = conn.prepareStatement(sql);
ResultSetMetaData metaData = ps.getMetaData();
’
without actually calling {{{}executeQuery(){}}}. However, the driver may still
send {{prepare}} or {{describe}} requests to the database. Semantically, the
SQL remains a full table scan, and the behavior regarding execution plans and
different JDBC drivers is not entirely clear.
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