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MySQL Connection Problem "Communications link failure"

thschu
Padawan

Hi Community,

were new at exasol and testing some feature with tableau. so first of all, i like to import from my mysql database to exa but were have some problemes with the connection.

Here is the log:

 

 

EXA_DB.COCKPIT> IMPORT INTO ARTICLE_GTIN FROM JDBC AT 'jdbc:mysql://IP:3306/DATABASE'
                USER 'username' IDENTIFIED BY 'password'
                    STATEMENT
                    ' SELECT * FROM articles_gtin'
[2021-10-06 12:42:17] [42636] ETL-5402: JDBC-Client-Error: Connecting to 'jdbc:mysql://IP:3306/DATABASE' as user='username' failed: Communications link failure
[2021-10-06 12:42:17] The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server. (Session: 1712863903151226880)

 

 

 

The firewall is not blocking any connection, the Port 3306 ist open for both sites. 

Any here had the same issue ?

Bests
Thomas 

1 ACCEPTED SOLUTION

Accepted Solutions

exa-Florian
Team Exasol
Team Exasol

After inspecting the problem the solution was found quickly. First step is to test network connectivity from Exasol to your source database using a Lua script from our toolbox: https://github.com/exasol/exa-toolbox/blob/master/utilities/check_connectivity.sql

This showed that no communication was possible on networking layer, the network settings have been adapted and connectivity has then been established successfully.

Now the database migration scripts for MySQL can be used to migrate the data: https://github.com/exasol/database-migration#mysql

 

________________________
Senior Sales Engineer @ Exasol

View solution in original post

6 REPLIES 6

exa-Chris
Exasol Alumni

Hi @thschu I will nudge someone internally. Did you have also have a look at our Migration Scripts? https://github.com/exasol/database-migration 

Christian

mwellbro
Xpert

Some time back there was a similar question: https://community.exasol.com/t5/discussion-forum/mysql-communication-link-failure-the-driver-has-not... 

Maybe there are some pointers for you there ?
@exa-Chris : there was no solution listed in the post I linked here - maybe once this one here is solved someone should
revisit the old topic ?

exa-Chris
Exasol Alumni

Thanks @mwellbro will do

exa-Peggy
Moderator
Moderator

Which MySQL-Version do you use?

What happens if you use useSSL=false in your connection string?

exa-Florian
Team Exasol
Team Exasol

After inspecting the problem the solution was found quickly. First step is to test network connectivity from Exasol to your source database using a Lua script from our toolbox: https://github.com/exasol/exa-toolbox/blob/master/utilities/check_connectivity.sql

This showed that no communication was possible on networking layer, the network settings have been adapted and connectivity has then been established successfully.

Now the database migration scripts for MySQL can be used to migrate the data: https://github.com/exasol/database-migration#mysql

 

________________________
Senior Sales Engineer @ Exasol

sashamik
Padawan

I'm having the same error message when trying to do a SELECT from a table in a virtual schema. Here is the error message:

 

[42636] ETL-5402: JDBC-Client-Error: Connecting to 'jdbc:mysql://HOST:3306' as user='username' failed: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.

 

 

I'm using Exasol 7.1.3. The source database for virtual schema is MySQL in Amazon RDS. I have also tested it with MariaDB and had the same error message.

My assumption was that network connectivity between Exasol and MySQL/MariaDB is somehow limited. I have used the check_connectivity script mentioned in this topic to test it. It returns OK. Another confusing moment is that virtual schema is created successfully and I can see the tables from MySQL in Exasol. Only SELECT doesn't work.

I'm out of ideas and would be grateful for some advice!