[HIVE-25257] Incorrect row order validation for query-based MAJOR compaction

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 4.0.0-alpha-1
• Component/s: Transactions
• Labels: pull-request-available
• Assignee: Marta Kuczora
• Reporter: Marta Kuczora
• Created: 16/Jun/21 14:02
• Updated: 17/Nov/22 08:48
• Resolved: 18/Jun/21 21:29

Description

In the insert query of the query-based MAJOR compaction, there is this function call: "validate_acid_sort_order(ROW_ID.writeId, ROWID.bucketId, ROW_ID.rowId)".
This is to validate if the order of the rows is correct. This validation is done by the GenericUDFValidateAcidSortOrder class and it assumes that the rows are in increasing order by bucketProperty, originalTransactionId and rowId.

But actually the rows should be ordered by originalTransactionId, bucketProperty and rowId, otherwise the delete deltas cannot be applied correctly. And this is the order what the MR MAJOR compaction writes and how the split groups are created for the query-based MAJOR compaction. It doesn't cause any issue until there is only one bucketProperty in the files, but as soon as there are multiple bucketProperties in the same file, the validation will fail. This can be reproduced by running multiple merge statements after each other.
For example:

CREATE TABLE transactions (id int,value string) STORED AS ORC TBLPROPERTIES ('transactional'='true');

INSERT INTO transactions VALUES
(1, 'value_1'),
(2, 'value_2'),
(3, 'value_3'),
(4, 'value_4'),
(5, 'value_5');

CREATE TABLE merge_source_1(ID int,value string) STORED AS ORC;
INSERT INTO merge_source_1 VALUES 
(1, 'newvalue_1'),
(2, 'newvalue_2'),
(3, 'newvalue_3'),
(6, 'value_6'),
(7, 'value_7');

MERGE INTO transactions AS T USING merge_source_1 AS S ON T.ID = S.ID 
WHEN MATCHED AND (T.value != S.value AND S.value IS NOT NULL) THEN UPDATE SET value = S.value 
WHEN NOT MATCHED THEN INSERT VALUES (S.ID, S.value);

CREATE TABLE merge_source_2(
 ID int,
 value string)
STORED AS ORC;

INSERT INTO merge_source_2 VALUES
(1, 'newestvalue_1'),
(2, 'newestvalue_2'),
(5, 'newestvalue_5'),
(7, 'newestvalue_7'),
(8, 'value_18);

MERGE INTO transactions AS T 
USING merge_source_2 AS S
ON T.ID = S.ID
WHEN MATCHED AND (T.value != S.value AND S.value IS NOT NULL) THEN UPDATE SET value = S.value
WHEN NOT MATCHED THEN INSERT VALUES (S.ID, S.value);

ALTER TABLE transactions COMPACT 'MAJOR';

The MAJOR compaction will fail with the following error:

Caused by: org.apache.hadoop.hive.ql.metadata.HiveException: Wrong sort order of Acid rows detected for the rows: org.apache.hadoop.hive.ql.udf.generic.GenericUDFValidateAcidSortOrder$WriteIdRowId@4d3ef25e and org.apache.hadoop.hive.ql.udf.generic.GenericUDFValidateAcidSortOrder$WriteIdRowId@1c9df436
	at org.apache.hadoop.hive.ql.udf.generic.GenericUDFValidateAcidSortOrder.evaluate(GenericUDFValidateAcidSortOrder.java:80)

So the validation doesn't check for the correct row order. The correct order is originalTransactionId, bucketProperty, rowId.

Issue Links

• links to: GitHub Pull Request #2400