[CASSANDRA-13086] CAS resultset sometimes does not contain value column even though wasApplied is false

• Type: Bug
• Status: Open
• Priority: Low
• Resolution: Unresolved
• Component/s: Feature/Lightweight Transactions, Legacy/CQL
• Labels: LWT
• Severity: Low
• Assignee: Unassigned
• Reporter: Christian Spriegel
• Created: 30/Dec/16 09:34
• Updated: 25/Oct/19 13:11

Description

Every now and then I see a ResultSet for one of my CAS queries that contain wasApplied=false, but does not contain my value column.

I just now found another occurrence, which causes the following exception in the driver:

...
Caused by: com.mycompany.MyDataaccessException: checkLock(ResultSet[ exhausted: true, Columns[[applied](boolean)]])
    at com.mycompany.MyDAO._checkLock(MyDAO.java:408)
    at com.mycompany.MyDAO._releaseLock(MyDAO.java:314)
    ... 16 more
Caused by: java.lang.IllegalArgumentException: value is not a column defined in this metadata
    at com.datastax.driver.core.ColumnDefinitions.getAllIdx(ColumnDefinitions.java:266)
    at com.datastax.driver.core.ColumnDefinitions.getFirstIdx(ColumnDefinitions.java:272)
    at com.datastax.driver.core.ArrayBackedRow.getIndexOf(ArrayBackedRow.java:81)
    at com.datastax.driver.core.AbstractGettableData.getBytes(AbstractGettableData.java:151)
    at com.mycompany.MyDAO._checkLock(MyDAO.java:383)
    ... 17 more

The query the application was doing:
delete from "Lock" where lockname=:lockname and id=:id if value=:value;

I did some debugging recently and was able to track these ResultSets to StorageProxy.cas() to the "CAS precondition does not match current values {}" return statement.

I saw this happening with Cassandra 3.0.10 and earlier versions.