I gave a try with master sources updated today.
I know nothing about socket so just followed step1 and step2 from https://www.jetbrains.com/help/datagrip/how-to-connect-to-mysql-with-unix-sockets.html#step-4-configure-the-mysql-driver-in-ide

the only difference was for step2, there was a lacking "d", I had to use:
mysql -u root -p -S /var/run/mysqld/mysqld.sock

not:
mysql -u root -p -S /var/run/mysqld/mysql.sock

Then, I launched LO and used "/var/run/mysqld/mysqld.sock" for socket, used "root" for user and used the password associated, I tested the connection, it was ok.

So the difference with you is I had to use a user/password.

(In reply to Julien Nabet from comment #1)
> 
> Then, I launched LO and used "/var/run/mysqld/mysqld.sock" for socket, used
> "root" for user and used the password associated, I tested the connection,
> it was ok.

You are connecting to the socket of MySQL/MariaDB, which isn't a separate instance.
The only socket I found on my system is the instance through
Socket → /run/user/1000/akonadi/mysql.socket

Akonadi is running on every system with KDE.
You don't need to start MySQK/MariaDB-server for connecting to this socket and connecting (this way) to the separate Akonadi instance.

It is impossible to connect to the separate Akonadi instance through the systemwide MySQL/MariaDB-server. Akonadi uses it's own server…

Ok since I don't use kde env (and so akonadi), I won't be able to test this.

Hey,

this is a long standing bug, I can confirm this for ages now. I get the same error when trying to connect to a local mariadb instance via a unix socket (non-tcp).

The same error shows:

"Can't connect to server on 'localhost' (111) at /usr/src/debug/libreoffice-fresh/libreoffice-7.5.3.2/connectivity/source/drivers/mysqlc/mysqlc_general.cxx:120"

It seems to me that using the unix socket is totally ignored, it always wants to connect via TCP, which my mariadb instance has disabled.

Can confirm the bug exists in some form using the versions listed below. I'm getting a different error, with different versions of LO, as listed below each version, listed below :-)

I can connect to the database directly using mysql on the console, with no password, as a regular user just as described in the original post.

Interestingly, with both versions, when the "Test Connection" button is clicked in the setup process, LO confirms the connection test as successful. After setting up the database connection, when LO gets to the Database home page, if the user clicks on an operation, like Queries, the connection error pops up.

Also tried each version with a username and password, and got the same errors. 

Version: 7.5.3.2 (X86_64)
Build ID: 50(Build:2)
CPU threads: 1; OS: Linux 6.3; UI render: default; VCL: kf5 (cairo+xcb)
Locale: en-US (en_US.UTF-8); UI: en-US
Calc: threaded

--The connection to the data source "akonaditest2" could not be established.

--Access denied for user 'adam'@'localhost' (using password: NO) at /builddir/build/BUILD  /libreoffice-7.5.3.2/connectivity/source/drivers/mysqlc/mysqlc_general.cxx:12

Version: 7.7.0.0.alpha0+ (X86_64) / LibreOffice Community
Build ID: 5a2c6f4df7149f8c1f543f120fe19bd66abfc189
CPU threads: 1; OS: Linux 6.3; UI render: default; VCL: kf5 (cairo+xcb)
Locale: en-US (en_US.UTF-8); UI: en-US
Calc: threaded

--The connection to the data source "akonaditest2" could not be established.

--Plugin sha256_password could not be loaded:  at /home/tdf/lode/jenkins/workspace/lo_gerrit/tb/src_master/connectivity/source/drivers/mysqlc/mysqlc_general.cxx:120

Bug is still the same with
Version: 25.2.4.3 (X86_64) / LibreOffice Community
Build ID: 33e196637044ead23f5c3226cde09b47731f7e27
CPU threads: 6; OS: Linux 6.4; UI render: default; VCL: kf5 (cairo+xcb)
Locale: de-DE (de_DE.UTF-8); UI: de-DE
Calc: threaded