Exactly what error is returned by PostgreSQL `FOR UPDATE NOWAIT` when a selected row cannot be locked immediately?

The PostgreSQL 9.4 documentation states that adding the NOWAIT option to a SELECT FOR UPDATE means an error is generated when a row cannot be locked:


To prevent the operation from waiting for other transactions to commit, use the NOWAIT option. With NOWAIT, the statement reports an error, rather than waiting, if a selected row cannot be locked immediately.

Exactly what error would that be?

As this is an acceptable condition, I want my Java code to check for such an expected error and then work around it.

SQLState: 55P03

In Postgres 9.4.x I tested this by performing an unresolved SELECT FOR UPDATE in pgAdmin and then doing a SELECT FOR UPDATE NOWAIT in my Java app. I used the JDBC driver JDBC41 Postgresql Driver, Version 9.4-1201.

The result was the following PostgreSQL Error Code.

• Message:

ERROR: could not obtain lock on row in relation "my_table_"

• Class:

Class 55 — Object Not In Prerequisite State

• SQLState:

55P03

• Condition Name:

lock_not_available

StackExchange Database Administrators Q#111176, answer score: 10