Concurrent reads and writes causes "BATproject2: does not match always" error

[nuno-faria]

Describe the bug
When executing concurrent reads and writes, particularly if the read query is large, the client returns the following error: GDK reported error: BATproject2: does not match always\nBATproject2: does not match always

This only seems to happen when the writes are updates or deletes.

Here is the log output:

DFLOWworker1018: BATproject2: !ERROR: does not match always
DFLOWworker1018: BATproject2: !ERROR: does not match always
DFLOWworker1018: createExceptionInternal: !ERROR: SQLException:sql.bind:GDK reported error: BATproject2: does not match always
DFLOWworker1018: createExceptionInternal: !ERROR: !ERROR: BATproject2: does not match always

To Reproduce
The following gist can be used to reproduce the error. In it, there are two clients, one executes writes over a simple table (k int, v int), while the other executes the query below:

SELECT k, sum(v)
FROM Test
GROUP BY k
ORDER BY sum(v) DESC

Software versions

• MonetDB master branch (most recent commit)
• Ubuntu 20.04 LTS
• Self-installed and compiled

[aris-koning]

Telepathy: we're already working on (hopefully) the same bug since last week. Fix is on the way. Thanks for reporting!

[PedroTadim]

The fix should be on default branch. Please test it.

[nuno-faria]

I cannot replicate the error anymore. Thank you all for looking into it.