[MDEV-17955] RocksDB: Server Collapse with certain Queries Created: 2018-12-10  Updated: 2023-04-27

Status: Open
Project: MariaDB Server
Component/s: Storage Engine - RocksDB
Affects Version/s: 10.3.11
Fix Version/s: 10.4

Type: Bug Priority: Major
Reporter: Juan Telleria Assignee: Sergei Petrunia
Resolution: Unresolved Votes: 0
Labels: index, rocksdb
Environment:

Windows

Attachments: File my.ini    

 Description   

When doing Bulk Loads, RocksDB gets stuck with some scheduled bulk load events with "Creating sort index". Under normal circumstances, the procedure should execute in a couple of minutes, but at time of reporting, it has been running for nearly 6 hours without any result...

SET STATEMENT
 
      rocksdb_commit_in_the_middle = 1,
 
      max_statement_time = 10800
 
FOR
 
     CREATE OR REPLACE TABLE t_table
 
     AS
 
          SELECT [...]

And if I try to kill the query, it does not get killed, causing performance issues to the whole server, and forcing a serve shutdown.

Which could be the root cause?

 Comments   
Comment by Sergei Petrunia [ 2018-12-11 ]

It is not clear why it got stuck.

What does SELECT * FROM INFORMATION_SCHEMA.processlist show about the hanging query?

Are there any other queries on the server that would be inserting rows into RocksDB tables? If not, can you check 

show status like 'rocksdb_rows_inserted';

Is it increasing?

Also, can you check 

SELECT * 
FROM INFORMATION_SCHEMA.rocksdb_trx
 
WHERE thread_id=<get the id column from INFORMATION_SCHEMA.processlist>

.
What does it show?

Comment by Juan Telleria [ 2018-12-13 ]

I cannot execute the previous check queries, as I already rebooted the server (And did migration back to InnoDB).

It showed "Creating sort index" for a query which shall have executed in a few minutes, for more than 6 hours... And after trying to KILL it, I saw killed, but the connection and the query did not disappear.

Comment by Juan Telleria [ 2018-12-13 ]

Maybe it is related to the table isolation level?

No idea

It also happened before however, but I could not see the backtrace for having no error log

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