PostgreSQL Ingestion Example
This page demonstrates how to setup a simple PostgreSQL database and query it from the kdb Insights Stream Processor.
PostgreSQL is an open-source relational database system. This example demonstrates how to setup a simple PostgreSQL database and query it from the kdb Insights Stream Processor.
This example is split into a install and query. If you already have a running PostgreSQL database, consider jumping to the query section.
Install a PostgreSQL database
This example uses scripts provided by Bitnami to install a PostgreSQL database.
The following initdb.sql is provided as an example to setup a database with mock data.
CREATE DATABASE finance;
\c finance
CREATE TABLE stocks (
id int,
sym varchar(10),
market varchar(10),
name varchar(255),
cap varchar(20)
);
INSERT INTO stocks VALUES (1, 'AAPL', 'NASDAQ', 'Apple Inc.', '$2.47T');
INSERT INTO stocks VALUES (2, 'MSFT', 'NASDAQ', 'Microsoft', '$2.32T');
To launch the PostgreSQL database in Docker, add a PostgreSQL service to a docker-compose.yaml
version: "3.3"
services:
psql:
image: docker.io/bitnami/postgres:latest
ports:
- 5432:5432
environment:
POSTGRES_USER: postgres
POSTGRES_PASSWORD: iamsecure
restart: always
volumes:
- ./initdb.sql:/docker-entrypoint-initdb.d/initdb.sql
Finally, run docker-compose up to launch the database.
Being by installing a PostgreSQL database into the current Kubernetes cluster.
helm install postgresql bitnami/postgresql
This should result in a postgresql image being launched in the current Kubernetes context.
kubectl get pods | grep postgresql
NAME READY STATUS RESTARTS AGE
postgresql-postgresql-0 1/1 Running 0 4h16m
The PostgreSQL image generates a random password. Extract the password from the cluster and store it in
and environment variable called PGPASSWORD for later use.
export PGPASSWORD=$(kubectl get secret postgresql -o jsonpath="{.data.postgresql-password}" | base64 --decode)
Adding mock data
Now that the database is running, add some mock data by interacting with a PostgreSQL client. Launch an interactive client by running the following.
kubectl run postgresql-client --rm --tty -i --restart='Never' \
--image docker.io/bitnami/postgresql:latest \
--env="PGPASSWORD=$PGPASSWORD" \
--command -- psql --host postgresql -U postgres -d postgres -p 5432
To add a mock stocks table with some mock data, run each of the following commands in the client shell from above.
CREATE DATABASE testdb;
CREATE USER testdbuser WITH PASSWORD 'testpass';
GRANT ALL PRIVILEGES ON DATABASE testdb TO testdbuser;
CREATE TABLE stocks (id int, sym varchar(10), market varchar(10), name varchar(255), cap varchar(20));
INSERT INTO stocks VALUES (1, 'AAPL', 'NASDAQ', 'Apple Inc.', '$2.47T');
INSERT INTO stocks VALUES (2, 'MSFT', 'NASDAQ', 'Microsoft', '$2.32T');
The end reult should have a table with the mock data added
SELECT * FROM stocks
id | sym | market | name | cap
----+------+--------+------------+--------
1 | AAPL | NASDAQ | Apple Inc. | $2.47T
2 | MSFT | NASDAQ | Microsoft | $2.32T
For next steps, see the guide on issuing a PostgreSQL query from the Stream Processor, continue to the querying guide.
Data examples
Another example using car sample data follows:
CREATE TABLE cars (id int, Name varchar(250), "Miles_per_Gallon" smallint, "Cylinders" smallint, "Displacement" smallint, "Horsepower" smallint, "Weight_in_lbs" smallint NOT NULL, "Acceleration" smallint, "Year" date NOT NULL, "Origin" character varying(60));
INSERT INTO cars VALUES (1, 'chevrolet chevelle malibu', 18, 8, 307, 130, 3504, 12, '1970-01-01', 'USA');
INSERT INTO cars VALUES (2, 'volkswagen 1131 deluxe sedan', 26, 4, 97, 46, 1835, 21, '1970-01-01', 'Europe');
The final table data should be as follows:
SELECT * FROM cars
id | name | Miles_per_Gallon | Cylinders | Displacement | Horsepower | Weight_in_lbs | Acceleration | Year | Origin
----+------------------------------+------------------+-----------+--------------+------------+---------------+--------------+------------+--------
1 | chevrolet chevelle malibu | 18 | 8 | 307 | 130 | 3504 | 12 | 1970-01-01 | USA
2 | volkswagen 1131 deluxe sedan | 26 | 4 | 97 | 46 | 1835 | 21 | 1970-01-01 | Europe
PostgreSQL queries
This section provides an overview of integrating the Stream Processor with a PostgreSQL database.
Mock Database Setup
This example uses a mock database which can be setup by following the PostgreSQL setup guide
The Stream Processor provides a reader interface for issuing queries on a PostgreSQL database. The PostgreSQL Reader API can be used as a data source in a pipeline.
The following spec.q will run a select query against a "finance" database and write it to
the console. The details of the database will be configured during deployment.
.qsp.run
.qsp.read.fromPostgres["SELECT * FROM stocks"; "finance"]
.qsp.write.toConsole[]
Deployment prerequisite
The example below requires a PostgreSQL database to be running in the cluster as setupm in the Kubernetes section of this tutorial.
jobname=$(curl -X POST http://localhost:5000/pipeline/create -d \
"$(jq -n --arg spec "$(cat spec.q)" --arg pass "$PGPASSWORD" \
'{
name : "psql",
type : "spec",
config : { content: $spec },
settings : { minWorkers: "1", maxWorkers: "10" },
env : {
KXI_SP_POSTGRES_SERVER : "postgresql",
KXI_SP_POSTGRES_PORT : "5432",
KXI_SP_POSTGRES_DATABASE : "finance",
KXI_SP_POSTGRES_USERNAME : "postgres",
KXI_SP_POSTGRES_PASSWORD : $pass
}
}' | jq -asR .)" | jq -r .id)
Once deployed, check the console output of the deployed spwork pod to see the result of the query.