Repro:

Run the following logictest:

# LogicTest: fakedist-disk

statement ok
CREATE TABLE t1 (x INT[]);
CREATE TABLE t2 (x INT[]);
INSERT INTO t1 VALUES (ARRAY[1, 2, NULL, 3]);
INSERT INTO t2 VALUES (ARRAY[1, 2, NULL, 3]);

query T
SELECT * FROM t1 INNER HASH JOIN t2 ON t1.x = t2.x
----
{1,2,NULL,3}

It will fail with an error that it is trying to encode the array as a table key. This is because the DiskRowContainer uses Encode to create a key for the rows it contains. It doesn't look like the solution is just to use Fingerprint however -- it assumes it can decode the hashed key back into the row that was placed in the container. For some types of fingerprint (JSON (and soon not to be arrays)) this is not true.

Jira issue: CRDB-4354