Wednesday, November 25, 2015

Postgresql upsert example with CTE (before upsert support from 9.5)

 with heartbeat_data (source, time) as (  
  values ('test', now())  
 update_query as (  
  update dvs_system.heartbeats  
    set last_beat = heartbeat_data.time  
  from heartbeat_data  
  where source_key = heartbeat_data.source  
  returning true as updated  
 insert into dvs_system.heartbeats (source_key, last_beat)  
  select source, time  
  from heartbeat_data  
  where not exists (  
   select 1 from update_query where updated = TRUE  


Monday, October 5, 2015

Postgres: Create a function to create a new logging table which inherits from another

When creating large logging tables, it better to define the structure of the logging table then create tables that inherit from that table, to put the data into. It makes look-ups on the table faster if you are searching for info in your logs relevant to data in one partitioned child table and it also makes it easier to trim the logs since you can just drop a child table of logs when the time is appropriate.


 CREATE OR REPLACE FUNCTION app_system.create_request_log_partition(_date timestamp without time zone)  
  RETURNS void AS  
      _table text := format('request_log_%s_q%s', date_part('year', _date), date_part('quarter', _date));  
            'CREATE TABLE system.'|| _table ||'() INHERITS (system.access_log);'||E'\n'  
           ||'CREATE INDEX '|| _table ||'_created_idx ON system.'|| _table ||'(created_at);'||E'\n'  
           ||'CREATE INDEX '|| _table ||'_api_request_idx ON system.'|| _table ||'(api_request);'||E'\n'  
           ||'GRANT INSERT, SELECT ON system.'|| _table ||' TO myapp;'||E'\n'  
 COST 100;  
 ALTER FUNCTION app_system.create_request_log_partition(timestamp without time zone) OWNER TO postgres;  

Tuesday, September 8, 2015

Generating self-signed SSL cert and PEM

Sign in as root then run this

cd /etc/ssl
openssl req -x509 -new -nodes -newkey rsa:2048 -keyout haproxy.key -out haproxy.crt
cat ./haproxy.crt ./haproxy.key > ./haproxy.pem

You can  name the files whatever you want instead of using "haproxy", which I use since I like to have SSL termination in my haproxy server.

Wednesday, September 2, 2015

Injection GIT branch / tag name into file

Prerequisite: In your project you need the file src/main/resources/

Of course you can adapt to using whatever file you want.

Note that this assumes you're using a "version=" property in your file

Step 1: Add the maven plugin to run an executable

1:  #!/usr/bin/env bash  
3:  # Get the git branch / tag name  
5:  # first, see of we have branch information (this will not be available if we checked out a tag)  
6:  TAG_OR_BRANCH="$(git rev-parse --abbrev-ref HEAD | egrep -o '([0-9]{1,}\.)+[0-9]{1,}')"  
8:  if [ "$TAG_OR_BRANCH" == "" ]; then  
10:    # if we can't get branch info, then we must be in a tag, so use that  
11:    TAG_OR_BRANCH="$(git describe | egrep -o '([0-9]{1,}\.)+[0-9]{1,}+(-b[0-9]{1,})')"  
12:  fi  
14:  # Remove the version from the properties file  
15:  sed -i '/^version=/ d' src/main/resources/static/version  
17:  # Add the version to the properties file  
18:  echo "Writing version $TAG_OR_BRANCH"  
19:  echo "version=$TAG_OR_BRANCH" >> src/main/resources/static/version  

Monday, August 3, 2015

Generate Golang struct (model) from Postgres tables

A handy Postgres SQL statement to generate Golang models (structs) for you.

WITH models AS (
  WITH data AS (
        replace(initcap(table_name::text), '_', '') table_name,
        replace(initcap(column_name::text), '_', '') column_name,
        CASE data_type
        WHEN 'timestamp without time zone' THEN 'time.Time'
        WHEN 'timestamp with time zone' THEN 'time.Time'
        WHEN 'boolean' THEN 'bool'
        -- add your own type converters as needed or it will default to 'string'
        ELSE 'string'
        END AS type_info,
        '`json:"' || column_name ||'"`' AS annotation    
    FROM information_schema.columns
    WHERE table_schema IN ('dvs_app', 'dvs_system')
    ORDER BY table_schema, table_name, ordinal_position
    SELECT table_name, STRING_AGG(E'\t' || column_name || E'\t' || type_info || E'\t' || annotation, E'\n') fields
    FROM data
    GROUP BY table_name
SELECT 'type ' || table_name || E' struct {\n' || fields || E'\n}' models
FROM models ORDER BY 1

Tuesday, June 30, 2015

Handy PowerShell Scripts

(because I don't want to add another GitHub repo)

Invert mouse scrolling (from

Get-ItemProperty HKLM:\SYSTEM\CurrentControlSet\Enum\HID\*\*\Device` Parameters FlipFlopWheel -EA 0 | ForEach-Object { Set-ItemProperty $_.PSPath FlipFlopWheel 1 }

Saturday, December 20, 2014

Anarchic Development Efforts

Nokia, once the leader in mobile technologies really messed up big. They were poised (perhaps) to be where Apple is today with the iPad and the iPhone however they had various deeply seeded problems which ultimately caused the demise of their R&D efforts. This interesting article is a great read for technology project managers. One of the most interesting things I found was the mention of "anarchic development efforts" at Nokia which was a major factor leading to ultimate project failure. By contrast the leadership culture at Apple has been very disciplined and focused under the collaborative-dictatorship of Steve Jobs. On a personal note, this is why, when I am heading up development teams, I have no time for "anarchic development efforts". Developers that don't get with the program must be let go or the entire project will be in jeopardy. I think this article highlights a sterling example of issue.