Can vertica doc team document the mechanics of lock timeouts ?

Colin, I have created a Jira for the documentation team to fix this. Thanks for your feedback. - Sarah

Hi,

The dc_lock_attempts data collector table contains a history of lock attempts (resolved requests). Note the key words "resolved requests" in the description.

The time out of 800 you see is probably your DB's current value of the LockTimeout config param:

select current_value, default_value, description from configuration_parameters where parameter_name = 'LockTimeout';

That param controls lock timeout for Tables and Projections.

The 1800 time out is for the system locks (Global Catalog [Meta-data global across all nodes], Local Catalog [Meta-data local to a node] and Cluster Topology)

Fyi ...

Global Catalog Locks - For the catalog that is global across all nodes, a GCL (X) lock is taken in scenarios including:

• DDL Commit
• DML Commit
• Refresh
• Recovery
• Segment Balancing
• Inviting a node to join the cluster

Local Catalog Locks - Only taken in X mode in scenarios including the following:

• DML and DDL
• Moveout
• Mergeout

Elastic Cluster Locks - Needed for scaling the cluster up or down to meet the needs of the database:

• Needs segments to be balanced
• EC lock (X) taken on a node while doing segment balancing
• Only one node is doing segment balancing at a time.

Finally, the 8 second time out is most likely for O locks on tables where you are modifying them (i.e. adding or dropping columns).

This is good ! Thanks for taking the time to write it Jim. I am sure other folks would benefit as well when they search for this type of info.