Forum: VoltDB Architecture

Post: Ad Hoc Planner task queue is full. Try again.

Ad Hoc Planner task queue is full. Try again.
Edson Ramiro
Aug 8, 2014
Hi all,

I'm executing some tests with VoltDB and I got this error message.

java.sql.SQLException: General Provider Error (GRACEFUL_FAILURE): 'Ad Hoc Planner task queue is full. Try again.'

I found no docs describing it, just this code: https://github.com/VoltDB/voltdb/blob/master/src/frontend/org/voltdb/compiler/AsyncCompilerAgent.java

What does this error message mean?

Thanks in advance,
jhugg
Aug 11, 2014
This is an error when the queue of SQL waiting to be planned by our SQL planner becomes full. This is essentially a different kind of backpressure. This usually occurs when a client is sending adhoc sql (such as JDBC) in a burst or at a high sustained rate. The solution is to throttle the rate on the client side, or for bursty workloads, try again. Another thing to consider is the queue limit of 250 is set per node. It may be possible in a cluster to connect to multiple nodes to achieve higher throughput.

We realize this is a bit tricky to work around and plan to make the experience with high volume or bursty SQL more smooth in an upcoming release.