Possible deadlock in forced rollback of UPDATE SET FROM statements
Details
| Detail name | Value |
|---|---|
| Changelog Number | 6364 |
| Type | Bug |
| Status | Resolved |
| Affected Versions | EXASOL 6.0.0 |
| Fix Versions | Exasol 6.0.11 |
| Resolution Date | 2018-07-18 |
Feature
In case of certain read and write table lock combinations, a transaction might be forcefully rolled back (exception). The order and/or kind of statements used can be optimized using SOL-562 to avoid such transaction conflicts.
Problem
When an UPDATE SET FROM statement is forcefully rollback back, it might happen that it hangs in exception handling (deadlock).
Such a statement can be recognized by an exceptionally long runtime, all in profile part COMPILE / EXECUTE (see EXA_USER_PROFILE_RUNNING). The hanging session can be killed using KILL SESSION.
Workaround
As the problem does only occur in forceful rollbacks, improving transactions using SOL-562 helps to avoid the bug along the enforced rollback.
