Обсуждение: Spurious failure to obtain row lock possible in PG 9.1?

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Spurious failure to obtain row lock possible in PG 9.1?

От
henk de wit
Дата:
I'm using Postgres 9.1 on Debian Lenny and via a Java server (JBoss AS 6.1) I'm executing a simple "select ... for update" query:

SELECT

importing

FROM

customer

WHERE

id = :customer_id

FOR UPDATE NOWAIT


Once every 10 to 20 times Postgres fails to obtain the lock for no apparent reason:

18:22:18,285 WARN  [org.hibernate.util.JDBCExceptionReporter] SQL Error: 0, SQLState: 55P03
18:22:18,285 ERROR [org.hibernate.util.JDBCExceptionReporter] ERROR: could not obtain lock on row in relation "customer"

I'm "pretty" sure there's really no other process that has the lock, as I'm the only one on a test DB. If I execute the query immediately again, it does succeed in obtaining the lock. I can however not reproduce this via e.g. PGAdmin.

Is it possible or perhaps even known that PG has this behavior, or should I look for the cause in the Java code? (I'm using Java EE"s entity manager to execute a native query inside an EJB bean that lets a JDBC connection from a pool join a JTA transaction.)

Thanks!