{
"cells": [
{
"cell_type": "markdown",
"id": "4797d7df",
"metadata": {},
"source": [
"# Introduction to databases"
]
},
{
"cell_type": "markdown",
"id": "11c7d73c",
"metadata": {},
"source": [
"## Thought experiment\n",
"\n",
"A set of tools that\n",
"\n",
"- manage data about students' grades, and\n",
"- do not utilize any dedicated database system.\n",
"\n",
"<br>\n",
"<br>\n",
"<br>\n",
"<br>\n",
"<br>\n",
"<br>\n",
"<br>\n",
"<br>\n",
"<br>\n",
"<br>\n",
"<br>\n",
"<br>\n",
"<br>\n",
"<br>\n",
"<br>\n",
"<br>\n",
"<br>\n",
"<br>\n",
"<br>\n",
"<br>\n",
"<br>\n",
"<br>\n",
"<br>"
]
},
{
"cell_type": "markdown",
"id": "ff3edbda",
"metadata": {},
"source": [
"## Text file based data storage example"
]
},
{
"cell_type": "code",
"execution_count": null,
"id": "8110ee4c",
"metadata": {},
"outputs": [],
"source": [
"from IPython import display"
]
},
{
"cell_type": "code",
"execution_count": null,
"id": "2b823019",
"metadata": {},
"outputs": [],
"source": [
"!./generate_students.py > students.textdb\n",
"print(\"idx lab prj exam\")\n",
"!cat students.textdb"
]
},
{
"cell_type": "markdown",
"id": "281b1468",
"metadata": {},
"source": [
"### Program to set data"
]
},
{
"cell_type": "code",
"execution_count": null,
"id": "0382b96e",
"metadata": {
"scrolled": false
},
"outputs": [],
"source": [
"display.Code(filename=\"./set_student_1.py\")"
]
},
{
"cell_type": "code",
"execution_count": null,
"id": "de7591c6",
"metadata": {},
"outputs": [],
"source": [
"!./set_student_1.py 512345 5.0 3.0 2.0\n",
"print(\"idx lab prj exam\")\n",
"!cat students.textdb"
]
},
{
"cell_type": "markdown",
"id": "842c4e01",
"metadata": {},
"source": [
"#### Simulated system/program crash"
]
},
{
"cell_type": "code",
"execution_count": null,
"id": "973ef24a",
"metadata": {},
"outputs": [],
"source": [
"!./set_student_1.py 512345 5.0 3.0 4.0 & sleep 1; kill %1\n",
"!cat students.textdb"
]
},
{
"cell_type": "markdown",
"id": "e4bf8578",
"metadata": {},
"source": [
"### Program to set data — attempt 2"
]
},
{
"cell_type": "code",
"execution_count": null,
"id": "53df4dc0",
"metadata": {},
"outputs": [],
"source": [
"display.Code(filename=\"set_student_2.py\")"
]
},
{
"cell_type": "code",
"execution_count": null,
"id": "d9f6691c",
"metadata": {
"scrolled": true
},
"outputs": [],
"source": [
"# start anew\n",
"!./generate_students.py > students.textdb\n",
"print(\"idx lab prj exam\")\n",
"!cat students.textdb"
]
},
{
"cell_type": "code",
"execution_count": null,
"id": "928b624f",
"metadata": {},
"outputs": [],
"source": [
"!./set_student_2.py 512345 5.0 3.0 4.0\n",
"!cat students.textdb"
]
},
{
"cell_type": "markdown",
"id": "dfae4a16",
"metadata": {},
"source": [
"#### Simulated simultaneous update"
]
},
{
"cell_type": "code",
"execution_count": null,
"id": "52d3e9db",
"metadata": {},
"outputs": [],
"source": [
"display.Code(filename=\"./set_students_2.sh\", language=\"shell\")"
]
},
{
"cell_type": "code",
"execution_count": null,
"id": "b263fe8f",
"metadata": {},
"outputs": [],
"source": [
"!./set_students_2.sh 514168 4.5 4.5 3.0\n",
"!cat students.textdb"
]
},
{
"cell_type": "markdown",
"id": "af5561e6",
"metadata": {},
"source": [
"### Program to set data — attempt 3"
]
},
{
"cell_type": "code",
"execution_count": null,
"id": "81c57c0c",
"metadata": {},
"outputs": [],
"source": [
"display.Code(filename=\"set_student_3.py\")"
]
},
{
"cell_type": "code",
"execution_count": null,
"id": "3f2a2692",
"metadata": {},
"outputs": [],
"source": [
"# start anew once again\n",
"!./generate_students.py > students.textdb\n",
"print(\"idx lab prj exam\")\n",
"!cat students.textdb"
]
},
{
"cell_type": "markdown",
"id": "2775f5f4",
"metadata": {},
"source": [
"#### Second simulated simultaneous update"
]
},
{
"cell_type": "code",
"execution_count": null,
"id": "f29937aa",
"metadata": {},
"outputs": [],
"source": [
"display.Code(filename=\"./set_students_3.sh\", language=\"shell\")"
]
},
{
"cell_type": "code",
"execution_count": null,
"id": "d97ae6d4",
"metadata": {},
"outputs": [],
"source": [
"!./set_students_3.sh 514168 4.5 4.5 3.0\n",
"!cat students.textdb"
]
},
{
"cell_type": "markdown",
"id": "9356d80d",
"metadata": {},
"source": [
"## Text file based data storage — summary\n",
"\n",
"- pros?\n",
"- cons?"
]
},
{
"cell_type": "code",
"execution_count": null,
"id": "9ac3d75c",
"metadata": {},
"outputs": [],
"source": [
"!cat /etc/passwd"
]
},
{
"cell_type": "markdown",
"id": "fd77558e",
"metadata": {},
"source": [
"## Client-server database\n",
"\n",
""
]
},
{
"cell_type": "markdown",
"id": "72229cfa",
"metadata": {},
"source": [
"_notes_\n",
"\n",
"- What you see is a typical setup of a computer program using a database server to store its data.\n",
"- The application sends commands in a data query/manipulation language (like SQL) to DBMS which parses that language and executes the commands.\n",
"- Most DMBSs store data in files but use sophisticated data structures and locking mechanisms to — when required — ensure atomicity, consistency, isolation and durability of performed operations.\n",
"- What communication channels can an application use to talk to its database server?"
]
},
{
"cell_type": "markdown",
"id": "b8dce746",
"metadata": {},
"source": [
"### Is network needed for communication with the DB?\n",
"\n",
""
]
},
{
"cell_type": "markdown",
"id": "c77bcb9b",
"metadata": {},
"source": [
"## Pervasiveness of databases\n",
"\n",
"\n",
"\n",
"### Graphics sources\n",
"\n",
"- <sup>https://publicdomainvectors.org/en/free-clipart/Isometric-server-cabinet-vector-graphics/13444.html</sup>\n",
"- <sup>https://publicdomainvectors.org/en/free-clipart/Computer-CPU-and-monitor-vector-image/21942.html</sup>\n",
"- <sup>https://publicdomainvectors.org/en/free-clipart/Smartphone-vector-clip-art/8352.html</sup>"
]
},
{
"cell_type": "markdown",
"id": "809c1351",
"metadata": {},
"source": [
"## Embedded databases\n",
"\n",
""
]
},
{
"cell_type": "markdown",
"id": "9b1a7e8a",
"metadata": {},
"source": [
"_notes_\n",
"\n",
"- Client-server scheme is often an overkill.\n",
"- A database engine that gets run _inside_ the application (e.g., as a programming library) can be called \"embedded\".\n",
"- One highly popular embedded database is named SQLite.\n",
"- An ordinary operating system — including mobile phone OSes — is likely to have tens or hundreds of small SQLite databases utilized by its various parts.\n",
"- How many small SQLite databases would one expect to find in a web browser profile?"
]
}
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