Error when Data Pipeline tries to connect to MySQL 8:

amazonaws.datapipeline.database.ConnectionFactory: Unable to establish connection to jdbc:mysql://<host> Could not create connection to database server.

Caused by: java.lang.RuntimeException: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server.

Cause is:

Connector/J" that is installed by AWS Data Pipeline does not work. You will need to replace it by adding your own external JDBC driver

Prerequisites for the new data pipeline

The MySQL JDBC driver "Connector/J" that is installed does not work. 

      You will need to download the correct version from Oracle.

        https://downloads.mysql.com/archives/c-j/

        Product Version

            Select 5.1.48

        Operating System

            Select Platform Independent

        Download the .tar.gz file to your local machine.

Start by replacing the Print head with an all metal hot end like the Micro-swiss

Then adjust the retraction settings in Cura to prevent strings in the print as follows:

Enable Retraction: Yes

Retraction Distance: Begin with a setting of 5 mm and adjust it up or down by 1 mm until all stringing is gone.

Retraction Speed: Begin with 50 mm/s and slow down if you are seeing filament damage.

Retraction Extra Prime Amount: Leave at 0

Maximum Retraction Count: Set to 10 and only adjust if you see filament damage.

Minimum Extrusion Distance Window: Set to your Retraction Distance

Nozzle Switch Retraction Distance: 16 mm

Nozzle Switch Retraction Speed: 20 mm/s 

Limit Support Retractions: Enable

Klipper is a special firmware designed to perform the heavy lifting of kinematics on a Raspberry Pi and simplify the job of the existing 3D printer mainboard. This allows very precise stepper motor timing and potentially much higher speeds.

Works with Octoprint. This allows the printer to be controlled using a regular web-browser. The same Raspberry Pi that runs Klipper can also run Octoprint.

In this video, a step by step guide to installing and configuring Klipper on an Ender 3. It includes the base set up as well as how to get a BLtouch and pressure advance working.

In the next part, I will tackle other boards and stepper motor drivers, including a Klipper specific board called the Printhat from Wrecklabs. I have tried to be as comprehensive as I can in this video but there is a lot to cover. Please read carefully through the docs I have referenced below.

Klipper Installation Guide: https://www.klipper3d.org/Installation.html

/**** ACCOUNT    ***************************************/
/* Show user SQL history with time and credits used */
use role accountadmin;
use database snowflake;
use schema account_usage;
use warehouse interactive_wh;
alter session set timestamp_output_format = 'YYYY-MM-DD HH:MI:SS';
select start_time, query_type, user_name, warehouse_name, to_number(total_elapsed_time/1000,10,2) as seconds, warehouse_size, (CREDITS_USED_CLOUD_SERVICES*300) as cost, query_text
from snowflake.account_usage.query_history
where warehouse_size is not NULL
--and query_type = 'SELECT'
--and warehouse_name = 'XXXXX'
--and role_name = 'XXXXX'
--and user_name = 'XXXXX'
order by 4 desc;

use role accountadmin;
use database snowflake;
use schema account_usage;
use warehouse interactive_wh;
select start_time, query_type, Role_name, user_name, warehouse_name, to_number(total_elapsed_time/1000,10,2) as seconds, bytes_scanned, rows_produced, rows_inserted, (CREDITS_USED_CLOUD_SERVICES*300) as cost, query_text
from snowflake.account_usage.query_history
where query_type <> 'GET_FILES'
and query_type <> 'PUT_FILES'
and query_type <> 'SHOW'
and to_date(start_time) between '2020-07-09' and '2020-08-25';

/* show space taken by tables */
select table_name, table_schema, to_varchar(active_bytes/1024/1024, 'F999,999,999,999.9') as Mbytes from snowflake.account_usage.table_storage_metrics
order b

Redshift Useful Queries

Redshift: Detect and Cancel Long running queries Per User Connection

Troubleshooting in Redshift

Show locked tables, highlight the query and run it, copy the pid

Show Locked Tables

/* Show locked Tables */
SELECT 
  current_time, 
  c.relname, 
  l.database, 
  l.transaction, 
  l.pid, 
  a.usename, 
  l.mode, 
  l.granted
FROM pg_locks l 
JOIN pg_catalog.pg_class c ON c.oid = l.relation
JOIN pg_catalog.pg_stat_activity a ON a.procpid = l.pid
WHERE l.pid <> pg_backend_pid();Show locks, oldest first

Kill Session (note change "pid" to a process with a lock from above)

/* kill session, Redshift ends session and rolls back all transactions that are associated with it. */
select pg_terminate_backend( pid )

Show locks, oldest first

Download SQL Workbench

Download Redshift JDBC driver

Start sqlworkbench

cd ~/Downloads/Workbench-Build125 && java -jar sqlworkbench.jar &

Create new connection

URL: jdbc:

redshift://my-cluster.my-database.us-east-1.redshift.amazonaws.com:5439/databasename?ssl=true&sslfactory=com.amazon.redshift.ssl.NonValidatingFactory

Use this script to create md5 password hash