Exception:virtuoso.jdbc4.VirtuosoException: SQ186: Over 20 keys in group by or hash join

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1

Hi there,

is there any parameter to be set in “virtuoso.ini” to accommodate the limitation in subject?
I’m on image 7.2.6-r2-gf5e32aa.

Best!
M

2

There are no INI file params to avoid such errors. In what context this error occurring, do you have a reproducible test case or query that produces the error etc ?

3

I have published a simplified query in here: https://gist.github.com/michimau/0380ebc00116d6ef13b0d7c1c991fe8c

It will run on http://cr.eionet.europa.eu/sparql (6.1.8 custom docker image)
it will fail on http://cr7.eionet.europa.eu/sparql (7.2.6-r2-gf5e32aa official)

4

Looks like the group_concat_distinct is causing the error as the query runs if it is removed. So looking into how it can be avoided …

5

This is just an example where group_concat_distinct is not even needed. But in principle it should not fail: it looks like some default settings on join hash are pretty conservative in 7.x.x, as the query works fine on 6.1.8.

6

Hello… I have the same error with a query with version 08.03.3331. Any news if this issue has a workaround solution?

7

There is a Virtuoso configuration file (virtuoso.ini) parameter MaxGroupByHashKeys in the [Parameters] that can set to a higher value than the default of 20 to increase the number of keys in GROUP BY or hash JOIN queries.