Query fails when there is column type mismatch between partition schema and table schema

Presto is failing to read the parquet partitions if the decimal datatype don’t match with what is in the hive metastore. Here is the error:

Query 20190130_224317_00018_w9d29 failed: There is a mismatch between the table and partition schemas. The types are incompatible and cannot be coerced. The column 'sbnum' in table 'default.presto_test' is declared as type 'decimal(8,0)', but partition 'month=201812' declared column 'sbnum' as type 'decimal(6,0)'.
com.facebook.presto.spi.PrestoException: There is a mismatch between the table and partition schemas. The types are incompatible and cannot be coerced. The column 'sbnum' in table 'default.presto_test' is declared as type 'decimal(8,0)', but partition 'month=201812' declared column 'sbnum' as type 'decimal(6,0)'.
                at com.facebook.presto.hive.HiveSplitManager.lambda$getPartitionMetadata$2(HiveSplitManager.java:315)
                at com.google.common.collect.Iterators$6.transform(Iterators.java:788)
                at com.google.common.collect.TransformedIterator.next(TransformedIterator.java:47)
                at com.google.common.collect.TransformedIterator.next(TransformedIterator.java:47)
                at com.google.common.collect.Iterators$ConcatenatedIterator.hasNext(Iterators.java:1340)
                at com.facebook.presto.hive.ConcurrentLazyQueue.poll(ConcurrentLazyQueue.java:37)
                at com.facebook.presto.hive.BackgroundHiveSplitLoader.loadSplits(BackgroundHiveSplitLoader.java:252)
                at com.facebook.presto.hive.BackgroundHiveSplitLoader.access$300(BackgroundHiveSplitLoader.java:91)
                at com.facebook.presto.hive.BackgroundHiveSplitLoader$HiveSplitLoaderTask.process(BackgroundHiveSplitLoader.java:185)
                at com.facebook.presto.hive.util.ResumableTasks.safeProcessTask(ResumableTasks.java:47)
                at com.facebook.presto.hive.util.ResumableTasks.access$000(ResumableTasks.java:20)
                at com.facebook.presto.hive.util.ResumableTasks$1.run(ResumableTasks.java:35)
                at io.airlift.concurrent.BoundedExecutor.drainQueue(BoundedExecutor.java:78)
                at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
                at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
                at java.lang.Thread.run(Thread.java:748)

Here are the steps to reproduce this issue -

1. Create partitioned table -

CREATE external TABLE `presto_test`(
  `sbnum` decimal(6,0),
  `abnum` decimal(8,0)
)
partitioned by (
month int
)
STORED AS PARQUET
LOCATION
  '/hive/presto_test'
;

2.Insert data into this table, create few partitions -

insert overwrite table presto_test partition (month=201801)
select sbnum, abnum from <tabname> limit 10
;

insert overwrite table presto_test partition (month=201802)
select sbnum, abnum from <tabname> limit 10
;

3.Access the table from Presto to ensure it works -

select count(1) from presto_test ;

4.alter the table, change the data type -

alter table presto_test change sbnum sbnum decimal (8,0) ;

5.Access the table again from presto -

select count(1) from presto_test ; (should throw an error)

6.Insert 1 more partition -

insert overwrite table presto_test partition (month=201803)
select sbnum, abnum from <tabname> limit 10
;

7.Access the table from presto again -

select count(1) from presto_test where month = 201802 ; (should work)

[hustnn]

Submit the initial PR trying to solving this issue https://github.com/prestosql/presto/pull/352.

The comment and suggestion are welcome.

[hustnn]

Hi @findepi . I am interested in it. Can I take it by referring @losipiuk 's previous work?