Moveout error while moving partitions

[guivert]

Hi,

In my ETL processes, I have a few lines like:

Code: Select all

select move_partitions_to_table ('stg.A', 0, 24, 'tmp_table.A')

erroring out with

Code: Select all

ERROR: A Moveout operation is already in progress on projection stg.B_all_nodes_b0 [txnid 45035996338570033 session fqdn-25466:0xd053]

In short, a moveout on table A fails because a moveout on table B is currently happening. On a sidenote, the error happens instantly, not after a timeout expired.

Does that make sense? One moveout per table I can understand, but one moveout only at a time for the whole cluster surely cannot be correct?

I did look at the tm pool, and the planned and max concurrency are 4 and 6 respectively. I upgrade the max concurrency to 20 but this made no difference at all.

This error happens only on Vertica 7.1.0-1. I upgraded yesterday from 6.3, and this is the only issue I get from the upgrade.

Would anybody have any idea how I could fix this short of downgrading?

Thanks,

[scutter]

You can probably work around this by enhancing your code to first check tuple_mover_operations for running moveouts, and close any internal sessions running moveouts. The drop_partition() function does this automaticaly. Sounds like move_partitions_to_table() should be doing it too. You may need a retry loop to make sure that your partition move succeeds.

Also worth looking into the moveouts that are running. If you’re hitting this consistently, it is because there are long-running moveouts, or is it because move_partitions_to_table() is triggering the move out?

—Sharon

[guivert]

Hi,

Thanks for your suggestion.

It turns out that move_partitions_to_table() does trigger a moveout. This is quite normal as Vertica will try to empty the WOS to disk before moving the partition.
That said, there is a bug in Vertica 7.1.0-1, which means that move_partitions_to_table() generates a moveout for all tables instead of only for the table in question. The effect is that you cannot run 2 move_partitions_to_table() in parallel, even on 2 unrelated tables.

Vertica support is now aware of this, and it will be fixed in a release soon.