David Svenson wrote:

Hi and thanks for the reply,

I'm not really delving into the optimizer layers. In fact - I didn't even intend for the optimizer to be enabled. I thought I have to enable it in order for it to run, so that basically leads me to this question:

How do I disable the opimizer? First, it should (is) not enabled in the distribution. To ensure, you can call the sql query:

select optimizer; &1 0 1 1 1 % . # table_name % single_value # name % varchar # type % 154 # length [ "inline,remap,evaluate,costModel,coercions,emptySet,aliases,mergetable,commonTerms,accumulators,deadcode,reduce,garbageCollector,dataflow,history,multiplex" ]

you can always set the optimizers explicitly with set optimizer='mmmmmmmm' but this requires some extra knowledge.

Thanks, David.

Martin Kersten wrote:

...

David Svenson wrote: Dear David,

Thank you for using MonetDB and more in particular that you are delving into the optimizer layers. Many of the optimizers are geared at specific experimentation in the development group, and not released as safe code. In particular, the remoteQuery optimizer was developed to experiment with peer-based querying, it has not been turned into a default optimizer, precisely because we have not explored a sufficiently large query space and in combination with others. Only the default optimizers are considered safe to use.

...

Hi all,

I am encountering strange exceptions that are related to the optimizer when working with the MAPI interface. I seem to be getting them when I use a few parallel threads to query the database (Always with the same query).

However, I don't get them in a consistent way - I can't reproduce an exact scenario. The exception messages I get also vary - but they are always related to the optimizer. Here are a few of the exception messages I got:

'optimizer.rsColumn' undefined in: _50:any := optimizer.rsColumn() 'calc.opt_remoteQueries' undefined in: _16:any := calc.opt_remoteQueries(_17:oid) 'optimizer.inc_parts' undefined in: _39:any := optimizer.inc_parts()

Sometimes, once I get one of these, any following query will give me an exception too, unless I restart MonetDB. In these cases I tried to run the query through mclient, and got the exception too, but followed by the expected query result.

Any idea where this is coming from and what I can do to prevent it?

turn off the remoteQuery optimizer and stick to the default list. Solutions for real distributed query processing are bing worked on as we speak.

...

Thanks, David.

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