Showing posts with label dbdeployer. Show all posts
Showing posts with label dbdeployer. Show all posts

Saturday, November 30, 2019

Fun with Bugs #90 - On MySQL Bug Reports I am Subscribed to, Part XXIV

Previous post in this series was published 3 months ago and the last Bug #96340 from it is already closed as fixed in upcoming MySQL 8.0.19. I've picked up 50+ more bugs to follow since that time, so I think I should send quick status update about interesting public MySQL bug reports that are still active.

As usual I concentrate mostly on InnoDB, replication and optimizer bugs. Here is the list, starting from the oldest:
  • Bug #96374  - "binlog rotation deadlock when innodb concurrency limit setted". This bug was reported by Jia Liu, who used gdb to show threads deadlock details. I admit that recently more bug reporters use gdb and sysbench with custom(ized) Lua scripts to prove the point, and I am happy to see this happening!
  • Bug #96378 - "Subquery with parameter is exponentially slower than hard-coded value". In my primitive test with user variables replaced by constants (on MariaDB 10.3.7) I get the same plan for the query, so I am not 100% sure that the analysis by my dear friend Sinisa Milivojevic was right and it's about optimization (and not comparing values with different collations, for example). But anyway, this problem reported by Jeff Johnson ended up as a verified feature request. Let's see what may happen to it next.
  • Bug #96379 - "First query successful, second - ERROR 1270 (HY000): Illegal mix of collations ". This really funny bug was reported by Владислав Сокол.
  • Bug #96400 - "MTS STOP SLAVE takes over a minute when master crashed during event logging". Nice bug report by Przemyslaw Malkowski from Percona, who used sysbench and dbdeployer to demonstrate the problem. Later Przemysław Skibiński (also from Percona) provided a patch to resolve the problem.
  • Bug #96412 - "Mess usages of latch meta data for InnoDB latches (mutex and rw_lock)". Fungo Wang had to make a detailed code analysis to get this bug verified. I am not sure why it ended up with severity S6 (Debug Builds) though.
  • Bug #96414 - "CREATE TABLE events in wrong order in a binary log.". This bug was reported by Iwo P. His test case to demonstarte the problem included small source code modification, but (unlike with some other bug reports) this had NOT prevented accepting it as a true, verified bug. The bug not affect MySQL 8.0.3+ thanks to WL#6049 "Meta-data locking for FOREIGN KEY tables" implemented there.
  • Bug #96472 - "Memory leak after 'innodb.alter_crash'". Yet another bug affecting only MySQL 4.7 and not MySQL 8.0. It was reported by Yura Sorokin from Percona.
  • Bug #96475 - "ALTER TABLE t IMPORT TABLESPACE blocks SELECT on I_S.tables.".  Clear and simple "How to repeat" instructions (using dbdeployer) by Jean-François Gagné. See also his related Bug #96477 - "FLUSH TABLE t FOR EXPORT or ALTER TABLE t2 IMPORT TABLESPACE broken in 8.0.17" for MySQL 8. The latter is a regression bug (without a regression tag), and I just do not get how the GA releases with such new bugs introduced may happen.
  • Bug #96504 - "Refine atomics and barriers for weak memory order platform". Detailed analysis, with links to code etc from Cai Yibo.
  • Bug #96525 - "Huge malloc when open file limit is high". Looks more like a systemd problem (in versions < 240) to me. Anyway, useful report from Andreas Hasenack.
  • Bug #96615 - "mysql server cannot handle write operations after set system time to the past". A lot of arguments were needed to get this verified, but Shangshang Yu was not going to give up. First time I see gstack used in the bug report to get a stack trace quickly. It's a part of gdb RPM on CentOS 6+. I have to try it vs gdb and pstack one day and decide what is the easiest and most efficient way to get backtraces of all threads in production...
  • Bug #96637 - "Clone fails on just upgraded server from 5.7". I had not used MySQL 8 famous clone plugin yet in practice, but I already know that it has bugs. This bug was reported by Satya Bodapati, who also suggested a patch.
  • Bug #96644 - "Set read_only on a master waiting for semi-sync ACK blocked on global read lock". Yet another problem (documented limitation) report from Przemyslaw Malkowski. Not sure why it was not verified on MySQL 8.0. Without a workaround to set master to read only it is unsafe to use long rpl_semi_sync_master_timeout values, as we may end up with that long downtime.
  • Bug #96677 - ""SELECT ... INTO var_name FOR UPDATE" not working in MySQL 8". This regression bug was reported by Vinodh Krish. Some analysis and patch were later suggested by Zsolt Parragi.
  • Bug #96690 - "sql_require_primary_key should not apply to temporary tables". This bug was also reported by Przemyslaw Malkowski from Percona. It ended up as a verified feature request, but not everyone in community is happy with this. Let me quote:
    "[30 Aug 8:08] Jean-François Gagné
    Could we know what was the original severity of this bug as reported by Przemyslaw ? This is now hidden as it has been reclassified as S4 (Feature Request).

    From my point of view, this is actually a bug, not a feature request and it should be classified as S2. A perfectly working application would break for no reason when a temporary table does not have a Primary Key, so this is actually a big hurdle for using sql_require_primary_key, hence serious bug in the implementation of this otherwise very nice and useful feature.
    "
That's all about bugs I've subscribed to in summer.
Winter is coming, so why not to remember nice warm sunny days and interesting MySQL bugs reported back then.
To summarize:
  1. We still see some strange "games" played during bugs processing and trend to decrease severity of reports. I think this is a waste of time for both Oracle engineers and community bug reporters.
  2. I am still not sure if Oracle's QA does not use ASan or just ignore problems reported for MTR test cases. Anyway, Percona engineers do this for them, and report related bugs :)
  3. dbdeployer and sysbench are really popular among MySQL bug reporters recently!
  4. Importing of InnoDB tablespaces is broken in MySQL 8.0.17+ at least.
  5. There are many interesting MySQL bugs reported during last 3 months, so I epxect more posts in this series soon.

Saturday, February 9, 2019

On my Favorite FOSDEM 2019 MySQL, MariaDB and Friends Devroom Talks

This year I had not only spoken about MySQL bugs reporting at FOSDEM, but spent almost the entire day listening at MySQL, MariaDB and Friends Devroom. I missed only one talk, on ProxySQL, (to get some water, drink a bottle of famous Belgian beer and chat with my former colleague in MySQL support team, Geert, whom I had not seen for a decade). So, for the first time out of my 4 FOSDEM visits I've got a first hand impression about the entire set of talks in the devroom that I want to share today, while I still remember my feelings.

Most of the talks have both slides and videos already uploaded on site, so you can check them and make your own conclusions, but my top 5 favorite talks (that have both videos and slides already available to community) were the following:

  • "Un-split brain (aka Move Back in Time) MySQL", by Shlomi Noach. You can find slides at SlideShare.

    This was a replacement talk that was really interesting and had proper style for FOSDEM. It was mostly a nice background story of creation of the gh-mysql-rewind tool, a shell script that uses MariaDB's mysqlbinlog --flashback option and MySQL GTIDs and allows to "rewind" row-based binary log to roll back transactions to some previous point in time. The tool should become available to community soon, maybe as a part of orchestrator. I was impressed how one can successfully use 49 slides for 20 minutes talk. That's far beyond my current presentation skills...
  • "Test complex database systems in a laptop with dbdeployer", by Giuseppe Maxia. You can find slides at SlideShare.

    I've already built and used dbdeployer, as described in my blog post, so I was really interested in the talk. Giuseppe was able not only to show 45 slides over 20 minutes and explain all the reasons behind re-implementing MySQL-Sandbox in Go, but also run a live demo where dozens of sandbox instances were created and used. Very impressive!
  • "MySQL and the CAP theorem: relevance & misconceptions", second great talk and show by Shlomi Noach. You can find slides at SlideShare.

    The "CAP theorem" says is a concept that a distributed database system (like any kind of MySQL replication setup) can only have 2 of the 3 features: (atomic) Consistency, (high) Availability and Partition Tolerance. This can be proved mathematically, but Shlomi had not only defined terms and conditions to present the formal proof, but also explained that they are far from real production objectives of any engineer or DBA (like 99.95% of Availability). He had shown typical MySQL setups (from simple async master-slave replication to Galera, group replication and even Vitess) and proved that formally they all are neither consistent nor available from that formal CAP theorem point of view, while, as we all know, they are practically useful and work (and with some efforts, proxies on top etc can be made both highly available and highly consistent for practical purposes). So, CAP theorem is neither representing real production systems, nor meeting their real requirements. We've also got some kind of explanation of why async master-master or circular replication are still popular... All that in 48 slides, with links, and presented in 20 minutes! Greatest short MySQL-related talk I've ever attended.
  • "TiDB: Distributed, horizontally scalable, MySQL compatible", by Morgan Tocker. You can find slides at SlideShare.

    It was probably the first time when I listened to Morgan, even though we worked together for a long time. I liked his way of explaining the architecture of this yet another database system speaking MySQL protocol and reasons to create it. If you are interested in performance of this system, check this blog post.
  • "MySQL 8.0 Document Store: How to Mix NoSQL & SQL in MySQL 8.0", by Frédéric Descamps. You can find slides (70!) at SlideShare.

    LeFred managed to get me somewhat interested in MySQL Shell and new JSON functions in MySQL, way more than ever before. It's even more surprising that hist talk was the last one and we already spent 8+ hours listening before he started. Simple step by step explanation of how one may get the best of both SQL, ACID and NoSQL (JSON, "MongoDB") worlds, if needed, in a single database management syste, was impressive. Also this talk probably caused the longest discussion and the largest number of questions from those remaining attendees.

    He was also one of two "hosts" and "managers" of the devroom, so I am really thankful him for hist efforts year after year to make MySQL devroom at FOSDEM great!
There were more good talks, but I had to pick up few that already have slides shared and those of a kind that I personally prefer to listen to at FOSDEM. This year I also missed few people whom I like to see and talk to at FOSDEM, namely Mark Callaghan and Jean-François Gagné.

The only photo I made with my Nokia dumb phone this year in Brussels, on my way to FOSDEM on February 2. We've got snow and rain that morning, nice for anyone who had to walk 5 kilometers to the ULB campus.
Overall, based on my experience this year, it still makes a lot of sense to visit FOSDEM for anyone interested in MySQL. You can hardly find so many good, different MySQL-related talks per just one single day on any other conference.

Tuesday, January 15, 2019

Using dbdeployer With MariaDB Server

Some time ago I've noted that one of the tools I use for testing various MySQL and MariaDB cases and to reproduce potential bugs, MySQL-Sandbox, is not updated any more. It turned out that active development switched to its port in Go called dbdeployer. You can find detailed information about dbdeployer and reasons behind developing it provided by its author, Giuseppe Maxia, here and there. See also this post at Percona blog for some quick review of its main features. One of the points of dbdeployer (and reasons to use Go) is that it is built once (per platform supported) somewhere and then binaries are downloaded from GitHub and used everywhere, without any problems with dependencies etc.

I've added checking dbdeployer to my long ToDo list, as I planned to use it (if not MySQL Sandbox) for some tests and posts related to resolving typical practical problems with MariaDB GTID-based replication. Yesterday I've allocated some time to finally try it and, as usual, I've started with building it from source (as for me databases-related software that I can not build from source on my test systems is not any attractive as something new to study and use). I was immediately surprised by the lack of instructions on how to do this at GitHub, no Makefile of any kind etc. All I was able to find is build.sh script. Correction: just check README.md on how to build it properly, as Giuseppe Maxia explained in the comment.

Good, regular structure is important for deployment
Fortunately this is not the first project written in Go that I try to build (or change somehow and then build). The first one was this replication manager (that has proper build instructions in docs). So, I though I knew what to do. I've installed missing golang package on my netbook with Ubuntu 14.04 that I had at hand and tried the following typical steps:
openxs@ao756:~/go$ export GOPATH=$HOME/go
openxs@ao756:~/go$ echo $GOPATH
/home/openxs/go
openxs@ao756:~/go$ go get github.com/datacharmer/dbdeployer
# github.com/datacharmer/dbdeployer/common
src/github.com/datacharmer/dbdeployer/common/strutils.go:170: undefined: sort.Slice
...
That was a bit surprising, but quick Google search shown that this could be caused by outdated (pre-1.8) version of golang package. So, dbdeployer requires golang 1.8 or newer and there was no such package for my good old Ubuntu (it has some 1.2.x only). One day I'll upgrade it, but so far I am OK with 14.04 for all other testing purposes, so I had to give up on the idea to build from source temporary. 

Today during few free minutes I've retried on my good old desktop box with Fedora 27 (where I surely built some Go project(s) successfully):
[openxs@fc23 go]$ uname -a
Linux fc23 4.18.19-100.fc27.x86_64 #1 SMP Wed Nov 14 22:04:34 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
[openxs@fc23 ~]$ ls go
pkg  src
[openxs@fc23 ~]$ echo $GOPATH

[openxs@fc23 ~]$ export GOPATH=$HOME/go
[openxs@fc23 ~]$ cd go
[openxs@fc23 go]$ go versiongo version go1.9.7 linux/amd64
This environment should work for build, so I've proceeded with:
[openxs@fc23 go]$ go get github.com/datacharmer/dbdeployer
[openxs@fc23 go]$ ls src/github.com/datacharmer/   jmoiron/       nsf/           tanji/
go-sql-driver/ mattn/         ogier/
[openxs@fc23 go]$ ls src/github.com/datacharmer/dbdeployer/
abbreviations/ compare/       docs/          mkreadme/      test/
.build/        concurrent/    .git/          rest/          unpack/
cmd/           cookbook/      .github/       sandbox/       vendor/
common/        defaults/      globals/       scripts/
Now let's try that scripts/build.sh with linux as a parameter, as it's a way to build Linux binaries based on what I found:
[openxs@fc23 go]$ MKDOCS=1 src/github.com/datacharmer/dbdeployer/scripts/build.sh linux
+ env GOOS=linux GOARCH=386 go build --tags docs -o dbdeployer-1.17.0-docs.linux .
+ env GOOS=linux GOARCH=amd64 go build -o sort_versions.linux sort_versions.go
/home/openxs/go/src/github.com/datacharmer/dbdeployer
-rwxrwxr-x. 1 openxs openxs 8.1M Jan 14 10:27 dbdeployer-1.17.0-docs.linux
-rw-rw-r--. 1 openxs openxs 3.0M Jan 14 10:27 dbdeployer-1.17.0-docs.linux.tar.gz
[openxs@fc23 go]$ ls
bin  pkg  src
[openxs@fc23 go]$ ls bin
dbdeployer
[openxs@fc23 go]$ bin/dbdeployer --version
dbdeployer version 1.17.0
Now we know how to build dbdeployer from source, if needed. If some dependencies are missing you'll be informed and similar go get ... command should allow to install it.

I was somewhat surprised to see MariaDB NOT mentioned at all in README.md. It says:
"DBdeployer is a tool that deploys MySQL database servers easily."
while good old MySQL-Sandbox also mentions MariaDB explicitly:
"This package is a sandbox for testing features under any version of MySQL from 3.23 to 8.0 (and any version of MariaDB.)"
So, my idea was to double check that dbdeployer is both MySQL-Sandbox compatible and MariaDB compatible (it is). I have several sandboxes already created in the past. I also have MariaDB 10.2.21 .tar.gz binaries that I want to use with dbdeployer for further testing:
[openxs@fc23 go]$ ls ~/sandboxes/
clear_all        rsandbox_mariadb-10_0_19  send_kill_all  test_replication
plugin.conf      rsandbox_mariadb-10_1_12  start_all      use_all
restart_all      rsandbox_mysql-8_0_12     status_all
rsandbox_8_0_12  sandbox_action            stop_all
[openxs@fc23 go]$ ls ~/*.tar.gz
/home/openxs/galera-25.3.22-x86_64.tar.gz
/home/openxs/galera-25.3.24-x86_64.tar.gz
/home/openxs/galera-25.3.25-glibc_214-x86_64.tar.gz
/home/openxs/mariadb-10.2.12-linux-x86_64.tar.gz
/home/openxs/mariadb-10.2.21-linux-x86_64.tar.gz
With dbdeployer one has to unpack .tar.gz first with dbdeployer unpack command. So, I tried it immediately:
[openxs@fc23 go]$ bin/dbdeployer unpack ~/mariadb-10.2.21-linux-x86_64.tar.gz
directory '/home/openxs/opt/mysql' not found
You should create it or provide an alternate base directory using --sandbox-binary
It seems the tool now wants to use ~/opt/mysql as a directory to unpack to, while MySQL_Sandbox silently used ~:
[openxs@fc23 go]$ ls ~ | grep 8.0
8.0.12
I made a lame try to force it to use ~, but failed for the reason I was too lazy to study:
[openxs@fc23 go]$ bin/dbdeployer --sandbox-binary=/home/openxs unpack /home/openxs/mariadb-10.2.21-linux-x86_64.tar.gzUnpacking tarball /home/openxs/mariadb-10.2.21-linux-x86_64.tar.gz to $HOME/10.2.21
.........100.........200....&tar.Header{Name:"mariadb-10.2.21-linux-x86_64/mysql-test/mysql-test-run", Mode:511, Uid:1021, Gid:1004, Size:0, ModTime:time.Time{wall:0x0, ext:63681810892, loc:(*time.Location)(0xa47aa0)}, Typeflag:0x32, Linkname:"./mysql-test-run.pl", Uname:"dbart", Gname:"my", Devmajor:0, Devminor:0, AccessTime:time.Time{wall:0x0, ext:0, loc:(*time.Location)(nil)}, ChangeTime:time.Time{wall:0x0, ext:0, loc:(*time.Location)(nil)}, Xattrs:map[string]string(nil)}
#ERROR: symlink ./mysql-test-run.pl mariadb-10.2.21-linux-x86_64/mysql-test/mysql-test-run: file exists
I just created ~/opt/mysql and proceeded with default configuration. After unpack step completed successfully I've proceeded with deploy step to create new replication sandbox:
[openxs@fc23 go]$ bin/dbdeployer unpack /home/openxs/mariadb-10.2.21-linux-x86_64.tar.gz
Unpacking tarball /home/openxs/mariadb-10.2.21-linux-x86_64.tar.gz to $HOME/opt/mysql/10.2.21
.........100.........200.........300.........400.........500.........600.........700.........800... ...
Renaming directory /home/openxs/opt/mysql/mariadb-10.2.21-linux-x86_64 to /home/openxs/opt/mysql/10.2.21

[openxs@fc23 go]$ bin/dbdeployer deploy replication 10.2.21
Installing and starting master
. sandbox server started
Installing and starting slave1
. sandbox server started
Installing and starting slave2
. sandbox server started
$HOME/sandboxes/rsandbox_10_2_21/initialize_slaves
initializing slave 1
initializing slave 2
Replication directory installed in $HOME/sandboxes/rsandbox_10_2_21
run 'dbdeployer usage multiple' for basic instructions'
We have access to nice enough documentation:
[openxs@fc23 go]$ bin/dbdeployer usage multiple
 USING MULTIPLE SERVER SANDBOX
On a replication sandbox, you have the same commands (run "dbdeployer usage single"),
with an "_all" suffix, meaning that you propagate the command to all the members.
Then you have "./m" as a shortcut to use the master, "./s1" and "./s2" to access
the slaves (and "s3", "s4" ... if you define more).

In group sandboxes without a master slave relationship (group replication and
multiple sandboxes) the nodes can be accessed by ./n1, ./n2, ./n3, and so on.

start_all    [options] > starts all nodes
status_all             > get the status of all nodes
restart_all  [options] > restarts all nodes
stop_all               > stops all nodes
use_all         "SQL"  > runs a SQL statement in all nodes
use_all_masters "SQL"  > runs a SQL statement in all masters
use_all_slaves "SQL"   > runs a SQL statement in all slaves
clear_all              > stops all nodes and removes all data
m                      > invokes MySQL client in the master
s1, s2, n1, n2         > invokes MySQL client in slave 1, 2, node 1, 2


The scripts "check_slaves" or "check_nodes" give the status of replication in the sandbox.
Typical sandbox directory (with some differences like use_all_slaves etc) is created in ~/sandboxes/ and shortcut commands work as expected:
[openxs@fc23 go]$ cd ~/sandboxes/rsandbox_10_2_21/
[openxs@fc23 rsandbox_10_2_21]$ ls
check_slaves       n2           sbdescription.json  test_sb_all
clear_all          node1        send_kill_all       use_all
initialize_slaves  node2        start_all           use_all_masters
m                  restart_all  status_all          use_all_slaves
master             s1           stop_all
n1                 s2           test_replication

[openxs@fc23 rsandbox_10_2_21]$ ls master/
add_option    init_db         restart             show_binlog    status   use
clear         load_grants     sbdescription.json  show_log       stop
data          my              sb_include          show_relaylog  test_sb
grants.mysql  my.sandbox.cnf  send_kill           start          tmp

[openxs@fc23 rsandbox_10_2_21]$ ls ../rsandbox_mariadb-10_1_12/
check_slaves             m       node1        s2             test_replication
clear_all                master  node2        send_kill_all  use_all
connection.json          n1      README       start_all
default_connection.json  n2      restart_all  status_all
initialize_slaves        n3      s1           stop_all

[openxs@fc23 rsandbox_10_2_21]$ ls ../rsandbox_mariadb-10_1_12/master/
add_option       default_connection.json  my              send_kill      tmp
change_paths     grants_5_7_6.mysql       mycli           show_binlog    use
change_ports     grants.mysql             my.sandbox.cnf  show_relaylog  USING
clear            json_in_db               proxy_start     start
connection.json  load_grants              README          status
data             msb                      restart         stop

[openxs@fc23 rsandbox_10_2_21]$ ./status_all
REPLICATION  /home/openxs/sandboxes/rsandbox_10_2_21
master : master on  -  port     23322 (23322)
node1 : node1 on  -  port       23323 (23323)
node2 : node2 on  -  port       23324 (23324)
[openxs@fc23 rsandbox_10_2_21]$ ./use_all "show variables like 'gtid%'"
# master
Variable_name   Value
gtid_binlog_pos 0-100-12
gtid_binlog_state       0-100-12
gtid_current_pos        0-100-12
gtid_domain_id  0
gtid_ignore_duplicates  OFF
gtid_seq_no     0
gtid_slave_pos
gtid_strict_mode        OFF
# server: 1
Variable_name   Value
gtid_binlog_pos
gtid_binlog_state
gtid_current_pos        0-100-12
gtid_domain_id  0
gtid_ignore_duplicates  OFF
gtid_seq_no     0
gtid_slave_pos  0-100-12
gtid_strict_mode        OFF
# server: 2
Variable_name   Value
gtid_binlog_pos
gtid_binlog_state
gtid_current_pos        0-100-12
gtid_domain_id  0
gtid_ignore_duplicates  OFF
gtid_seq_no     0
gtid_slave_pos  0-100-12
gtid_strict_mode        OFF
[openxs@fc23 rsandbox_10_2_21]$ ./m
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 14
Server version: 10.2.21-MariaDB-log MariaDB Server

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

master [localhost:23322] {msandbox} ((none)) > show master status;
+------------------+----------+--------------+------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.000001 |     2835 |              |                  |
+------------------+----------+--------------+------------------+
1 row in set (0.00 sec)

master [localhost:23322] {msandbox} ((none)) > show variables like 'gtid%';
+------------------------+----------+
| Variable_name          | Value    |
+------------------------+----------+
| gtid_binlog_pos        | 0-100-12 |
| gtid_binlog_state      | 0-100-12 |
| gtid_current_pos       | 0-100-12 |
| gtid_domain_id         | 0        |
| gtid_ignore_duplicates | OFF      |
| gtid_seq_no            | 0        |
| gtid_slave_pos         |          |
| gtid_strict_mode       | OFF      |
+------------------------+----------+
8 rows in set (0.00 sec)

master [localhost:23322] {msandbox} ((none)) > exit
Bye
For my further tests I needed slaves to have log_slave_updates enabled and gtid_strict_mode=ON. So, I've added these settings to my.sandbox.cnf in node1 and node2 subdirectories for both slaves and restarted them:
[openxs@fc23 rsandbox_10_2_21]$ ./restart_all# executing 'stop' on /home/openxs/sandboxes/rsandbox_10_2_21
stop /home/openxs/sandboxes/rsandbox_10_2_21/node1
stop /home/openxs/sandboxes/rsandbox_10_2_21/node2
stop /home/openxs/sandboxes/rsandbox_10_2_21/master
# executing 'start' on /home/openxs/sandboxes/rsandbox_10_2_21
executing 'start' on master
. sandbox server started
executing 'start' on slave 1
. sandbox server started
executing 'start' on slave 2
. sandbox server started
I need a table to play with and I want to check that slaves are in sync:
[openxs@fc23 rsandbox_10_2_21]$ ./m
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 12
Server version: 10.2.21-MariaDB-log MariaDB Server

Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

master [localhost:23322] {msandbox} ((none)) > use test
Database changed
master [localhost:23322] {msandbox} (test) > create table t1(id int primary key, c1 int);
Query OK, 0 rows affected (0.17 sec)

master [localhost:23322] {msandbox} (test) > exit
Bye
[openxs@fc23 rsandbox_10_2_21]$ ./use_all "show variables like 'gtid%'"
# master
Variable_name   Value
gtid_binlog_pos 0-100-13
gtid_binlog_state       0-100-13
gtid_current_pos        0-100-13
gtid_domain_id  0
gtid_ignore_duplicates  OFF
gtid_seq_no     0
gtid_slave_pos
gtid_strict_mode        OFF
# server: 1
Variable_name   Value
gtid_binlog_pos 0-100-13
gtid_binlog_state       0-100-13
gtid_current_pos        0-100-13
gtid_domain_id  0
gtid_ignore_duplicates  OFF
gtid_seq_no     0
gtid_slave_pos  0-100-13
gtid_strict_mode        ON
# server: 2
Variable_name   Value
gtid_binlog_pos 0-100-13
gtid_binlog_state       0-100-13
gtid_current_pos        0-100-13
gtid_domain_id  0
gtid_ignore_duplicates  OFF
gtid_seq_no     0
gtid_slave_pos  0-100-13
gtid_strict_mode        ON
[openxs@fc23 rsandbox_10_2_21]$
Note the value of gtid_current_pos on master and gtid_slave_pos on each slave. They are the same and slaves are in sync. If you want to find out more about the format of GTIDs in MariaDB or all that gtid% server variables, please, check this KB article.

* * *

To summarize, dbdeployer is a nice port of MySQL-Sandbox into Go, with some additional features. It can be easily built from source if you have golang version 1.8 or newer (or just downloaded if you have not). Sandboxes created with dbdeployer may co-exists with older sandboxes in the same default directory (but .tar.gz files are unpacked into different directory by default). It still works well with MariaDB. I am going to use replication sandboxes built with it for some further testing of various real life use cases and problems of MariaDB's GTIDs implementation (that may be presented in further posts).