Github user srowen commented on a diff in the pull request:
https://github.com/apache/spark/pull/14377#discussion_r73189845
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/jdbc/OracleDialect.scala ---
@@ -26,30 +26,38 @@ private case object OracleDialect extends JdbcDialect {
override def canHandle(url: String): Boolean =
url.startsWith("jdbc:oracle")
- override def getCatalystType(
- sqlType: Int, typeName: String, size: Int, md: MetadataBuilder):
Option[DataType] = {
+ override def getCatalystType(sqlType: Int, typeName: String, size: Int,
md: MetadataBuilder):
+ Option[DataType] = sqlType match {
// Handle NUMBER fields that have no precision/scale in special way
// because JDBC ResultSetMetaData converts this to 0 precision and
-127 scale
// For more details, please see
// https://github.com/apache/spark/pull/8780#issuecomment-145598968
// and
// https://github.com/apache/spark/pull/8780#issuecomment-144541760
- if (sqlType == Types.NUMERIC && size == 0) {
- // This is sub-optimal as we have to pick a precision/scale in
advance whereas the data
- // in Oracle is allowed to have different precision/scale for each
value.
+ case Types.NUMERIC if size == 0 =>
Option(DecimalType(DecimalType.MAX_PRECISION, 10))
+ // Handle FLOAT fields in a special way because JDBC ResultSetMetaData
converts
+ // this to NUMERIC with -127 scale
+ // Not sure if there is a more robust way to identify the field as a
float (or other
+ // numeric types that do not specify a scale.
+ case Types.NUMERIC if md.build().getLong("scale") == -127 =>
--- End diff --
@wangyum I can merge this, since it looks reasonable, even though I'm not
an Oracle expert. Can we streamline this a bit by only computing
`md.build().getLong("scale")` once? The repeated matching of `Types.NUMERIC`
could be done once in an `if` statement and be clearer.
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