[CALCITE-3866] "numeric field overflow" when running the generated SQL in PostgreSQL

[wenhuitang]

Pull request for https://issues.apache.org/jira/browse/CALCITE-3866
As for aggregate function sum, most of the time, its return type is equal to its operand's type, but if its operand's type has precision, the precision of the result may be larger than the oeprans's type. So may be we can set precision to the Max value if the oeprand's type has precision, especially for the type decimal.

[XuQianJin-Stars]

LGTM +1

[hsyuan]

+1

[DonnyZone]

Hi, @wenhuitang, could you please rebase and resolve the conflict? We can merge it into 1.23.0.
Moreover, I suggest to simplify the title and commit message as:
"numeric field overflow" when running the generated SQL in PostgreSQL

[DonnyZone]

I investigated the return type for sum function in Hive[1] and Spark[2]. It seems they both compute the precision as Math.min(MAX_PRECISION, inputPrecision + 10). Maybe we can align with them.
@wenhuitang @XuQianJin-Stars @hsyuan WDYT?

[1]https://github.com/apache/hive/blob/54b87999fa0c23f9902faae609e7441e0693a22b/ql/src/java/org/apache/hadoop/hive/ql/udf/generic/GenericUDAFSum.java#L247

[2]https://github.com/apache/spark/blob/272d229005b7166ab83bbb8f44a4d5e9d89424a1/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Sum.scala#L56

[wenhuitang]

I investigated the return type for sum function in Hive[1] and Spark[2]. It seems they both compute the precision as Math.min(MAX_PRECISION, inputPrecision + 10). Maybe we can align with them.
@wenhuitang @XuQianJin-Stars @hsyuan WDYT?

[1]https://github.com/apache/hive/blob/54b87999fa0c23f9902faae609e7441e0693a22b/ql/src/java/org/apache/hadoop/hive/ql/udf/generic/GenericUDAFSum.java#L247

[2]https://github.com/apache/spark/blob/272d229005b7166ab83bbb8f44a4d5e9d89424a1/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Sum.scala#L56

Thanks a lot. I have rebased this pr. IMO, as for computing precision as Math.min(MAX_PRECISION, inputPrecision + 10), I did not find any theory or standard for it. To avoid the problem completely, it would be ok with max precision.

[DonnyZone]

LGTM!