Comment 2 for bug 1859100

Problem 2 is an intermittent problem:

(PROBLEM #2)

CURRENT_TEST: main.subquery_sj_mat_bka

--- /home/rafaeldtinoco/work/sources/general/ubuntu/mysql-8.0-8.0.18/mysql-test/r/subquery_sj_mat_bka.result 2019-09-20 11:30:51.000000000 +0300
+++ /home/rafaeldtinoco/work/sources/general/ubuntu/mysql-8.0-8.0.18/builddir/mysql-test/var/9/log/subquery_sj_mat_bka.reject 2020-01-09 19:54:09.659290415 +0300
@@ -12800,10 +12800,10 @@
             -> Hash
                 -> Table scan on <subquery2>
                     -> Materialize with deduplication
- -> Filter: (t1.col_int_key is not null) (cost=3.40 rows=7)
- -> Filter: (t3.col_int is null) (cost=3.40 rows=7)
- -> Nested loop left join (cost=3.40 rows=7)
- -> Index scan on t1 using col_int_key (cost=0.95 rows=7)
+ -> Filter: (t1.col_int_key is not null) (cost=4.15 rows=7)
+ -> Filter: (t3.col_int is null) (cost=4.15 rows=7)
+ -> Nested loop left join (cost=4.15 rows=7)
+ -> Index scan on t1 using col_int_key (cost=1.70 rows=7)

This test calculates the cost of a query with BKA (Batched Key Access) feature enabled:

"""
set optimizer_switch='batched_key_access=on,mrr_cost_based=off';

--source t/subquery_sj_mat.test

set optimizer_switch=default;
"""

explain format=tree SELECT * FROM t4 WHERE (col_int_key) IN ( SELECT t1.col_int_key FROM t1 LEFT JOIN ( t2 JOIN t3 ON t3.col_int_key = t2.col_int ) USING ( pk ) WHERE t3.col_int IS NULL) ORDER BY col_int_key;

And it looks like optimizer switching makes test to have different costs sometimes. Nevertheless, after fixing (PROBLEM #1) I was able to fully build MySQL Server binary packages without triggering (PROBLEM #2).

dpkg-deb: building package 'mysql-server' in '../mysql-server_8.0.18-0ubuntu4_all.deb'.
dpkg-deb: building package 'mysql-testsuite-8.0' in '../mysql-testsuite-8.0_8.0.18-0ubuntu4_amd64.deb'.
dpkg-deb: building package 'mysql-source-8.0' in '../mysql-source-8.0_8.0.18-0ubuntu4_amd64.deb'.
dpkg-deb: building package 'mysql-client' in '../mysql-client_8.0.18-0ubuntu4_all.deb'.
dpkg-deb: building package 'mysql-testsuite' in '../mysql-testsuite_8.0.18-0ubuntu4_all.deb'.
dpkg-deb: building package 'mysql-router' in '../mysql-router_8.0.18-0ubuntu4_amd64.deb'.
dpkg-deb: building package 'mysql-server-8.0' in '../mysql-server-8.0_8.0.18-0ubuntu4_amd64.deb'.