Cancel query

Zingman, Jonathan

10 Jun 2019 10 Jun '19

10:58 p.m.

In the cookbook, you give a good way to find out the status of queries by using the sys.query() call, which returns the list of queries tagged in various ways. Our question is whether there is any way to access, e.g., the tag value. In our application, we need to occasionally cancel queries from our UI. The UI has no direct knowledge of the query. While we might be able to find the query we want to cancel by comparing the query text, our automatically generated queries can be very long, and if there's some internal reformatting by Monetdb, we might not get an exact match. So is there anything in the handle or elsewhere that we can use to identify the query we want to cancel? JONATHAN ZINGMAN Manager - TrueCall Data [logos] 2855 Telegraph Ave, Suite 200 Berkeley, CA, 94705-1169 DIRECT: 510.809.0423 CELL: 510.823.5638 www.netscout.comhttp://www.netscout.com/

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Ying (Jennie) Zhang

11 Jun 11 Jun

8:38 p.m.

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On 11 Jun 2019, at 00:58, Zingman, Jonathan wrote:

In the cookbook, you give a good way to find out the status of queries by using the sys.query() call,

Hai, Jonathan, MonetDB doesn’t have a function called sys.query(). Did you mean sys.queue() instead?

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which returns the list of queries tagged in various ways. Our question is whether there is any way to access, e.g., the tag value. In our application, we need to occasionally cancel queries from our UI. The UI has no direct knowledge of the query. While we might be able to find the query we want to cancel by comparing the query text, our automatically generated queries can be very long, and if there’s some internal reformatting by Monetdb, we might not get an exact match. So is there anything in the handle or elsewhere that we can use to identify the query we want to cancel?

Correct me if I’m wrong, but I’m not aware of a feature with which you can query the qtag of a query. Some code study will be needed to see if it’s feasible to add such feature, and how. You can probably get away with string matching, since MonetDB doesn’t do much/any reformatting next to to-lowercase. Not sure how much text the “query” field of sys.queue() holds. In addition, please be aware that i) sys.queue() is originally develop for debugging purpose… ii) the minimal cancellation entity is a function, i.e., when MonetDB is busy executing a very long running function, a cancellation will only take effect *after* that function has finished => then MonetDB won’t continue executing the next function. Regards, Jennie

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JONATHAN ZINGMAN Manager – TrueCall Data

2855 Telegraph Ave, Suite 200 Berkeley, CA, 94705-1169

DIRECT: 510.809.0423 CELL: 510.823.5638 www.netscout.com

_______________________________________________ users-list mailing list users-list@monetdb.org https://www.monetdb.org/mailman/listinfo/users-list

Martin Kersten

8:56 p.m.

On 11/06/2019 22:38, Ying (Jennie) Zhang wrote:

...

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On 11 Jun 2019, at 00:58, Zingman, Jonathan wrote:

In the cookbook, you give a good way to find out the status of queries by using the sys.query() call,

Hai, Jonathan,

MonetDB doesn’t have a function called sys.query(). Did you mean sys.queue() instead?

...
which returns the list of queries tagged in various ways. Our question is whether there is any way to access, e.g., the tag value. In our application, we need to occasionally cancel queries from our UI. The UI has no direct knowledge of the query. While we might be able to find the query we want to cancel by comparing the query text, our automatically generated queries can be very long, and if there’s some internal reformatting by Monetdb, we might not get an exact match. So is there anything in the handle or elsewhere that we can use to identify the query we want to cancel?

Correct me if I’m wrong, but I’m not aware of a feature with which you can query the qtag of a query. Some code study will be needed to see if it’s feasible to add such feature, and how.

You can probably get away with string matching, since MonetDB doesn’t do much/any reformatting next to to-lowercase. Not sure how much text the “query” field of sys.queue() holds.

In addition, please be aware that i) sys.queue() is originally develop for debugging purpose… ii) the minimal cancellation entity is a function, i.e., when MonetDB is busy executing a very long running function, a cancellation will only take effect *after* that function has finished => then MonetDB won’t continue executing the next function.

Small correction here, with function we mean a MAL function call. So, if the system is executing a very time consuming join, it will *not* be interrupted, but rather at the end of it the query in which is rans is terminated.

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Regards, Jennie

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JONATHAN ZINGMAN Manager – TrueCall Data

2855 Telegraph Ave, Suite 200 Berkeley, CA, 94705-1169

DIRECT: 510.809.0423 CELL: 510.823.5638 www.netscout.com

_______________________________________________ users-list mailing list users-list@monetdb.org https://www.monetdb.org/mailman/listinfo/users-list

_______________________________________________ users-list mailing list users-list@monetdb.org https://www.monetdb.org/mailman/listinfo/users-list

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Martin Kersten
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Cancel query

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