April 2025 - discuss - lists.mariadb.org

presenting binary data as hex strings by default
by Jaco Kroon 07 Apr '25

07 Apr '25

Hi All, This would be a mis-feature probably, but please bear with me. Getting binary data dumped to a terminal is not fun. Is there perhaps a way to set it such that *binary types would be displayed/presented as hex string rather than raw binary? In particular when using CLI tools? I'm aware of the HEX() function which achieves same, but you need to do that for every column, when inspecting data and just starting off with something like "select * from" ... I suspect having a flag to inform the cli client tools to present such binary columns as hexadecimal strings instead of dumping raw binary data to the terminal would be most helpful. Sorry, just had a round of screeching in my ears from "bell" characters and was just wondering if there's a way to not only stop that, but present the data in a more sensible manner regardless, ideally some "opt in" mechanism to maintain backwards compatibility. Kind regards, Jaco

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Adding an index to a large table
by edi mari 04 Apr '25

04 Apr '25

Hi, I have a 200GB table with a foreign key constraint, and I need to drop an existing index and add a non-unique index to it. What is the best approach to do this with minimal impact on users? Thanks Edi

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it is normal to have a memory usage of 85%?
by cata 04 Apr '25

04 Apr '25

Hi everybody, I am new here and I am confronted with a situation, so I will start with the questions first: 1. It is normal that on my server, mariadb to use almost 85% of available ram or something is wrong? 2. In case I want to limit the whole application (mariadb) to not use more than 5.5 GB RAM from total of 7.8GB it could be possible - without affecting it's performance? 3. Is anything to optimize (change) now? If yes, which variable? 4. Do we need more RAM for this server or actual RAM could be enough? See below: Operating system: "Debian 12.10 (bookworm)" MariaDB Version: 10.11.11-MariaDB-0+deb12u1-log The server was configured (limited) to use for InnoDB -> max 3GB Ram MariaDB [(none)]> SHOW GLOBAL VARIABLES LIKE 'innodb_buffer_pool_size'; +-------------------------+------------+ | Variable_name | Value | +-------------------------+------------+ | innodb_buffer_pool_size | 3221225472 | +-------------------------+------------+ 1 row in set (0.001 sec) But, on that server *we are running also MySam, Memory *and Innodb, in total, ~70 databases (8 MySam, 1 MEMORY, and the rest are InnoDB) MariaDB [mysql]> select count(distinct db) from db; +--------------------+ | count(distinct db) | +--------------------+ | 73 | +--------------------+ 1 row in set (0.001 sec) MariaDB [mysql]> SYSTEM 4CPU, 7.8GB RAM root@adsns-db-node0:~# df -h Filesystem Size Used Avail Use% Mounted on udev 3.8G 0 3.8G 0% /dev tmpfs 776M 764K 775M 1% /run /dev/sda1 150G 48G 97G 34% / tmpfs 3.8G 0 3.8G 0% /dev/shm tmpfs 5.0M 0 5.0M 0% /run/lock /dev/sda15 241M 138K 241M 1% /boot/efi tmpfs 776M 0 776M 0% /run/user/0 root@adsns-db-node0:~# I found some articles on internet regarding /dev/shm, which could influence mysql performance. In my case /dev/shm is not used even defined, so the system could use the whole available RAM - 7.8GB RAM, so I excluded this as possible cause. MariaDB [(none)]> SHOW VARIABLES LIKE '%buffer_size%'; +----------------------------+-----------+ | Variable_name | Value | +----------------------------+-----------+ | aria_pagecache_buffer_size | 134217728 | | aria_sort_buffer_size | 268434432 | | bulk_insert_buffer_size | 8388608 | | innodb_log_buffer_size | 16777216 | | innodb_sort_buffer_size | 1048576 | | join_buffer_size | 4194304 | | key_buffer_size | 10485760 | | mrr_buffer_size | 262144 | | myisam_sort_buffer_size | 134216704 | | preload_buffer_size | 32768 | | read_buffer_size | 131072 | | read_rnd_buffer_size | 262144 | | sort_buffer_size | 2097152 | +----------------------------+-----------+ 13 rows in set (0.001 sec) Traffic is not high, just 123 queries per second. MariaDB [(none)]> status; -------------- mysql Ver 15.1 Distrib 10.11.11-MariaDB, for debian-linux-gnu (x86_64) using EditLine wrapper Connection id: 877596 Current database: Current user: root@localhost SSL: Not in use Current pager: stdout Using outfile: '' Using delimiter: ; Server: MariaDB Server version: 10.11.11-MariaDB-0+deb12u1-log Debian 12 Protocol version: 10 Connection: Localhost via UNIX socket Server characterset: utf8mb4 Db characterset: utf8mb4 Client characterset: utf8mb3 Conn. characterset: utf8mb3 UNIX socket: /run/mysqld/mysqld.sock Uptime: 7 days 3 hours 24 min 6 sec Threads: 78 Questions: 75901186 Slow queries: 4891595 Opens: 12573592 Open tables: 2000 Queries per second avg: 123.007 -------------- MariaDB [(none)]> Even I am restarting mariadb, after a short time, the memory usage is 85% root@adsns-db-node0:~# free -g total used free shared buff/cache available Mem: 7 6 0 0 0 1 Swap: 0 0 0 root@adsns-db-node0:~# The swap is not used, just the memory, which is ok. CPU usage is less than ~10%, so is ok. See below, output of top. %Cpu(s): 2.2 us, 0.7 sy, 0.0 ni, 96.2 id, 0.4 wa, 0.0 hi, 0.4 si, 0.0 st MiB Mem : 7750.8 total, 161.4 free, 6351.8 used, 712.6 buff/cache MiB Swap: 0.0 total, 0.0 free, 0.0 used. 1399.0 avail Mem PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 1555028 mysql 20 0 7752424 6.5g 15476 S 10.6 85.2 188:29.16 mariadbd root@adsns-db-node0:~# pstree |grep maria |-mariadbd---51*[{mariadbd}] root@adsns-db-node0:~# All 51 childs of mariadb are using 85% from the system memory (each child ~1.6% of total RAM). I found a mysql calculator and changing innodb_buffer_pool_size - its default value 8M - with 3G, I got ~3.7GB ... still not 6.6G (aprox 85% from total RAM). See: https://www.mysqlcalculator.com/ 5. Why this difference, from 3.7GB up to 6.6GB? 6. Where could it be the rest of 2GB which is used by mariadb (from 3.7GB up to 6.6GB)? Any help will be appreciated. Catal

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10.11.8 writing all binary logs in row format (even though format is MIXED)
by mariadb＠Biblestuph.com 03 Apr '25

03 Apr '25

Doing a little fishing here ... Does someone know of a reason why a downstream replica would--seemingly spontaneously--start writing ALL of its binary log entries in ROW format, even though binlog_format is MIXED? This replica has been running for quite some time, though admittedly I had to restore it from a backup about 3 weeks ago as the result of a server crash. But it had been writing data fine over those three weeks (and prior); starting on March 2nd it started writing all of its entries in ROW format. I didn't notice until it filled the disk this morning. I can't think of anything that may have changed at that time. Normally a few entries will get written as ROW but most are definitely MIXED in normal operation. I stopped/restarted it this morning and it's writing in MIXED again, as expected. I also checked the upstream primary, it is _not_ writing its records as ROW. I.E., my replica is (apparently) not getting them that way from upstream. Both are 10.11.8. Any ideas? TIA, Dan

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InnoDB buffer pool usage drops regularly since 10.11.10 / 11.4.4
by William David Edwards 02 Apr '25

02 Apr '25

Hi, We see an odd pattern where InnoDB buffer pool usage drops regularly. Attached are two screenshots of memory usage on an 11.4.4 node: one at 20:15 with an InnoDB buffer pool of 47,5 GiB, and 5 minutes later with a 3,69 GiB one. The times at which this occurs are -seemingly- random. Other internal memory structures are stable. On at least one node with this issue, the InnoDB buffer pool is smaller (48 GiB) than the sum of data + indexes (87,57 GiB). As far as I can see (graphing history is limited), this has started occurring after upgrading from MariaDB 10.11.9 to 10.11.10 and from 11.4.3 to 11.4.4 respectively. At first sight, in the pre-release notes for 10.11.11 and 11.4.5, I don't see any related issues. To make absolutely sure this is related to the upgrade, we will be downgrading a troubled node tonight, to see if it fixes anything. I will report back. In userland, these drops cause a domino effect: no cache -> more I/O -> slower queries -> nuisance in application. Has anyone else seen this pattern, possibly after upgrading to the aforementioned versions? Although 1) neither of these versions are bleeding edge and 2) I haven't seen any such reports, asking is worth a shot as this started occurring on several machines after upgrading with no configuration nor (obvious) usage changes. With kind regards, William David Edwards

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active-backup or active-active solution in docker swarm
by vbvbrj 01 Apr '25

01 Apr '25

Hello. Did anyone managed to create a master-backup or master-master deployment of mariadb in docker swarm to work consistent and stable? Community, please help me with a yaml config in docker swarm to deploy a master-active or better master-master config of mariadb which will handle servers restart on full stack shutdown and restart without any implications. Can someone who did this share theirs yaml config for docker swarm? I tried the examples on percona page and as data was populated the synconizations of services were lost. Thank you.

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