Github user sureshthalamati commented on the pull request: https://github.com/apache/spark/pull/8676#issuecomment-139410536 @rxin Even if spark is running on jdk1.7, customers using older version of drivers will run into AbstractMethodError exception. I think adding requirement for customers to use new drivers that implement getSchema() function will be unnecessary. After implementing the current approach I got curious on how the jdbc read functionality finds the meta data and learned org.apache.spark.sql.execution.datasources.jdbc.JDBCRDD.resolveTable also uses s"SELECT * FROM $table WHERE 1=0" to get column information. Alternative approach is to add getMetadataQuery(table:string) to the JdbcDialect interface that helps to determine if table exists for write case , and column type information in the case of read instead of getTableExistsQuery() as implemented in the current pull request. It might be a milli second slower in the case of write call for dialects that specify âselect 1 from $table limit 1", instead of âselect * from $table limit 1â. Advantage is one method to the interface will address both the cases. Any comments ?
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