> desc disk;

+---------+---------------------+------+-----+---------+-------+

| Field   | Type                | Null | Key | Default | Extra |

+---------+---------------------+------+-----+---------+-------+

| label   | varchar(10)         | NO   | PRI | NULL    |       |

| size    | bigint(20) unsigned | NO   |     | NULL    |       |

| re      | tinyint(3) unsigned | NO   |     | NULL    |       |

| unavail | bigint(20) unsigned | YES  |     | NULL    |       |

+---------+---------------------+------+-----+---------+-------+

4 rows in set (0.01 sec)

> select count(*) from disk;

ERROR 2006 (HY000): MySQL server has gone away

No connection. Trying to reconnect...

Connection id:    4

Current database: bdr

ERROR 2013 (HY000): Lost connection to MySQL server during query

% cat /var/log/mysql/mysqld.err

..[snip]..

2021-09-19 13:25:28 0 [Note] /usr/local/libexec/mariadbd: ready for connections.

Version: '10.5.12-MariaDB-log'  socket: '/var/run/mysql/mysql.sock'  port: 3306  FreeBSD Ports

2021-09-19 13:25:28 0 [Note] InnoDB: Buffer pool(s) load completed at 210919 13:25:28

2021-09-19 13:25:32 0x81f27bf00  InnoDB: Assertion failure in file /wrkdirs/usr/ports/databases/mariadb105-server/work/mariadb-10.5.12/storage/innobase/btr/btr0pcur.cc line 520

InnoDB: Failing assertion: page_is_comp(next_page) == page_is_comp(page)

InnoDB: We intentionally generate a memory trap.

InnoDB: Submit a detailed bug report to https://jira.mariadb.org/

InnoDB: If you get repeated assertion failures or crashes, even

InnoDB: immediately after the mysqld startup, there may be

InnoDB: corruption in the InnoDB tablespace. Please refer to

InnoDB: https://mariadb.com/kb/en/library/innodb-recovery-modes/

InnoDB: about forcing recovery.

210919 13:25:32 [ERROR] mysqld got signal 6 ;

This could be because you hit a bug. It is also possible that this binary

or one of the libraries it was linked against is corrupt, improperly built,

or misconfigured. This error can also be caused by malfunctioning hardware.

To report this bug, see https://mariadb.com/kb/en/reporting-bugs

We will try our best to scrape up some info that will hopefully help

diagnose the problem, but since we have already crashed, 

something is definitely wrong and this may fail.

Server version: 10.5.12-MariaDB-log

key_buffer_size=134217728

read_buffer_size=131072

max_used_connections=1

max_threads=153

thread_count=2

It is possible that mysqld could use up to 

key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 467792 K  bytes of memory

Hope that's ok; if not, decrease some variables in the equation.

Thread pointer: 0x81fc0fb98

Attempting backtrace. You can use the following information to find out

where mysqld died. If you see no messages after this, something went

terribly wrong...

stack_bottom = 0x7fffded02f38 thread_stack 0x49000

0x130cd6c <my_print_stacktrace+0x3c> at /usr/local/libexec/mariadbd

0xc6e6af <handle_fatal_signal+0x28f> at /usr/local/libexec/mariadbd

0x801904e00 <_pthread_sigmask+0x530> at /lib/libthr.so.3

Trying to get some variables.

Some pointers may be invalid and cause the dump to abort.

Query (0x81fc64d30): select count(*) from disk

Connection ID (thread ID): 4

Status: NOT_KILLED

Optimizer switch: index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on,index_merge_sort_intersection=off,engine_condition_pushdown=off,index_condition_pushdown=on,derived_merge=on,derived_with_keys=on,firstmatch=on,loosescan=on,materialization=on,in_to_exists=on,semijoin=on,partial_match_rowid_merge=on,partial_match_table_scan=on,subquery_cache=on,mrr=off,mrr_cost_based=off,mrr_sort_keys=off,outer_join_with_cache=on,semijoin_with_cache=on,join_cache_incremental=on,join_cache_hashed=on,join_cache_bka=on,optimize_join_buffer_size=on,table_elimination=on,extended_keys=on,exists_to_in=on,orderby_uses_equalities=on,condition_pushdown_for_derived=on,split_materialized=on,condition_pushdown_for_subquery=on,rowid_filter=on,condition_pushdown_from_having=on,not_null_range_scan=off

The manual page at https://mariadb.com/kb/en/how-to-produce-a-full-stack-trace-for-mysqld/ contains

information that should help you find out what is causing the crash.

Core pattern: %N.core

2021-09-19 13:25:33 0 [Note] InnoDB: Uses event mutexes

2021-09-19 13:25:33 0 [Note] InnoDB: Compressed tables use zlib 1.2.11

2021-09-19 13:25:33 0 [Note] InnoDB: Number of pools: 1

2021-09-19 13:25:33 0 [Note] InnoDB: Using generic crc32 instructions

2021-09-19 13:25:33 0 [Note] InnoDB: Initializing buffer pool, total size = 134217728, chunk size = 134217728

2021-09-19 13:25:33 0 [Note] InnoDB: Completed initialization of buffer pool

2021-09-19 13:25:33 0 [Note] InnoDB: Starting crash recovery from checkpoint LSN=17580653,17580653

2021-09-19 13:25:33 0 [Note] InnoDB: Last binlog file '/var/db/mysql/log/mysql-bin.000011', position 171168

2021-09-19 13:25:33 0 [Note] InnoDB: 128 rollback segments are active.

2021-09-19 13:25:33 0 [Note] InnoDB: Removed temporary tablespace data file: "ibtmp1"

2021-09-19 13:25:33 0 [Note] InnoDB: Creating shared tablespace for temporary tables

2021-09-19 13:25:33 0 [Note] InnoDB: Setting file './ibtmp1' size to 12 MB. Physically writing the file full; Please wait ...

2021-09-19 13:25:33 0 [Note] InnoDB: File './ibtmp1' size is now 12 MB.

2021-09-19 13:25:33 0 [Note] InnoDB: 10.5.12 started; log sequence number 17580737; transaction id 23194

2021-09-19 13:25:33 0 [Note] InnoDB: Loading buffer pool(s) from /var/db/mysql/ib_buffer_pool

2021-09-19 13:25:33 0 [Note] Plugin 'FEEDBACK' is disabled.

2021-09-19 13:25:33 0 [Note] Recovering after a crash using /var/db/mysql/log/mysql-bin

2021-09-19 13:25:33 0 [Note] Starting crash recovery...

2021-09-19 13:25:33 0 [Note] Crash recovery finished.

2021-09-19 13:25:33 0 [Note] Server socket created on IP: '0.0.0.0'.

2021-09-19 13:25:33 0 [Note] Reading of all Master_info entries succeeded

2021-09-19 13:25:33 0 [Note] Added new Master_info '' to hash table

2021-09-19 13:25:33 0 [Note] /usr/local/libexec/mariadbd: ready for connections.

Version: '10.5.12-MariaDB-log'  socket: '/var/run/mysql/mysql.sock'  port: 3306  FreeBSD Ports

2021-09-19 13:25:33 0 [Note] InnoDB: Buffer pool(s) load completed at 210919 13:25:33