Mingli Rui created SPARK-40802:
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Summary: [SQL] Enhance JDBC Connector to use
PreparedStatement.getMetaData() to resolve schema instead of
PreparedStatement.executeQuery()
Key: SPARK-40802
URL: https://issues.apache.org/jira/browse/SPARK-40802
Project: Spark
Issue Type: Improvement
Components: SQL
Affects Versions: 2.1.0
Reporter: Mingli Rui
Currently, Spark JDBC Connector uses *PreparedStatement.executeQuery()* to
resolve the JDBCRelation's schema. The schema query is like *s"SELECT * FROM
$table_or_query WHERE 1=0".*
But it is not necessary to execute the query. It's enough to *prepare* the
query. With preparing the statement, the query is parsed and compiled, but is
not executed. It will be more efficient.
So, it's better to use PreparedStatement.getMetaData() to resolve schema.
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