dmagda

Electron lets you detect the system-level change events via the powerMonitor module.

The snippet below shows how to receive screen lock/unlock and sleep/awake events of your screen.

const {app, BrowserWindow, powerMonitor} = require('electron')


const path = require('node:path')

dmagda

Multi-Tenancy Notes

SaaS services are a typical example of multi-tenant applications. With multi-tenancy, it's possible to build scalable and cost-effective services by sharing resources accross several customers (tenants). The multi-tenant architecture assumes data isolation and fine-grained security controls to ensure that one tenant's data stays private or only accessible by other tenants under certain conditions.

Let's take an example of a Shopify-like company where merchants can easily launch their own eCommerce website and start selling products/services online.

Postgres and Multi-Tenancy

dmagda

"Movies Recommendations"

client.sql(
    "SELECT id, title, overview, vote_average " +
    "FROM movie WHERE vote_average >= 7 " +
    "AND genres @> \'[{\"name\": \"Science Fiction\"}]\'" +
    "AND 1 - (overview_vector <=> :prompt_vector::vector) >= 0.7 " +
    "ORDER BY overview_vector <=> :prompt_vector::vector LIMIT 3")
 .param("prompt_vector", promptEmbedding.toString())

dmagda

Create a custom Docker network:

docker network create custom-network

Start YugabyteDB:

rm -r ~/yb_docker_data
mkdir ~/yb_docker_data

dmagda

orders = jdbcTemplate.query(
    "SELECT * FROM pizza_order WHERE id = ? and location = ?::store_location",
    (prepStmt) -> {
        prepStmt.setInt(1, id);
        prepStmt.setString(2, location);
    },
    new OrderRowMapper());

dmagda

1. Stop all the K3s processes:

   sudo kill $(ps aux | grep 'k3s' | awk '{print $2}')

2. Create the k3s_uninstall.sh script with the following content and execute it:

   #!/bin/sh
   set -x
   systemctl stop k3s

systemctl disable k3s

dmagda

Start YugabyteDB Instance

rm -r ~/yb_docker_data
mkdir ~/yb_docker_data

docker network create custom-network

docker run -d --name yugabytedb_node1 --net custom-network \
  -p 15433:15433 -p 7001:7000 -p 9000:9000 -p 5433:5433 \

dmagda

                StringBuilder queryString = "insert into test (id, f1) values ";
                
                // add placeholder for values
                for (int counter = 0; counter <= 100; counter += 1) 
                    queryString.append("(?, ?),");

                // replace the trailing ',' with a ';'
                queryString.replace(queryString.length() - 1, queryString.length(), ";");

dmagda

/*******************************************************************************
   Chinook Database - Version 1.4
   Script: Chinook_PostgreSql.sql
   Description: Creates and populates the Chinook database.
   DB Server: PostgreSql
   Author: Luis Rocha
   License: http://www.codeplex.com/ChinookDatabase/license
********************************************************************************/

dmagda

Nested Loop Join

// Loading records that satisfy the WHERE predicate.
// Can be an index or full table scan.
var subsetTable1 = getData(table1, wherePredicate);
var subsetTable2 = getData(table2, wherePredicate);

var resultSet = new LinkedList();