sarutak commented on a change in pull request #31442:
URL: https://github.com/apache/spark/pull/31442#discussion_r569634360
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File path: docs/sql-migration-guide.md
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@@ -24,6 +24,8 @@ license: |
## Upgrading from Spark SQL 3.1 to 3.2
+ - In Spark 3.2, money type in PostgreSQL table is converted to `StringType`
and money[] type is not supported due to the JDBC driver for PostgreSQL can't
handle those types properly.
Review comment:
> Why not a string array for a money array?
For money type, Spark SQL calls `PgResultSet.getDouble` causing the error.
```
[info] org.apache.spark.SparkException: Job aborted due to stage failure:
Task 0 in stage 0.0 failed 1 times, most recent failure: Lost task 0.0 in stage
0.0 (TID 0) (192.168.1.204 executor driver): org.postgresql.util.PSQLException:
Bad value for type double : 1,000.00
[info] at
org.postgresql.jdbc.PgResultSet.toDouble(PgResultSet.java:3104)
[info] at
org.postgresql.jdbc.PgResultSet.getDouble(PgResultSet.java:2432)
[info] at
org.apache.spark.sql.execution.datasources.jdbc.JdbcUtils$.$anonfun$makeGetter$5(JdbcUtils.scala:418)
```
So, we can avoid this issue by mapping money type to `StringType` to let
Spark SQL call `getString` rather than `getDouble`.
For money[] type, on the other hand, the PostgreSQL's JDBC driver calls
`PgResultSet.toDouble` internally.
```
[info] at
org.postgresql.jdbc.PgResultSet.toDouble(PgResultSet.java:3104)
[info] at
org.postgresql.jdbc.ArrayDecoding$5.parseValue(ArrayDecoding.java:235)
[info] at
org.postgresql.jdbc.ArrayDecoding$AbstractObjectStringArrayDecoder.populateFromString(ArrayDecoding.java:122)
[info] at
org.postgresql.jdbc.ArrayDecoding.readStringArray(ArrayDecoding.java:764)
```
We can control how Spark SQL gets the value from the array obtained by
`PgResultSet.getArray`, but it's difficult to control how the JDBC driver
handles the elements in the array which is to be returned.
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