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Redis and Postgres basics

Redis and Postgres basics

Anjali Chauhan
·Sep 30, 2021·

3 min read

REDIS [ Remote Dictionary Server ] Open-source, non-relational kind of database and caching server.

HOW IT WORKS!

  • Redis resides in RAM/memory.

  • Data that needs to be in continuous use, should be in RAM.

  • RAM is present in the CPU whereas, the hard disk is not that close to the CPU.

  • RAM has fast retrieval of Data than Hard disk.

  • The data in Redis is stored as a JSON form

  • We don't store heavy data in RAM, RAM will slow down, the whole system will slow down

  • The Data that execute with conditional is store in the database not in RAM.

  • Redis is an in-memory data structure store, used as a database, cache, and message broker.

  • Redis provides data structures such as strings, hashes, lists, sets, sorted sets with range queries, bitmaps etc.

BASICS COMMANDS

SET name anjali (set/create key anjali)

GET name

DEL name

KEYS *

EXISTS name

FLUSHALL(delete everything)

ttl name(get the remaining time of key expiry in seconds)

Expire name 10(will expire the key in 10 sec)

  • -2 defines that key has been expired*

Setex name 10 anjali (set name along with expiry)

lpush(pushing at extreme left )

rpush(pushing at extreme right)

[ lpush name key ]

[rpush name key]

redis01.png

redis02.png

reedis03.png

redis04.png

🔥NOTE :-> PostgreSQL is a relational database, first and foremost, whereas Redis is a key-value store. That said, you could use PostgreSQL as a key-value store, simply because many relational database products do not dictate that you use the relational model

🏁PostgreSQL (pronounced as post-gress-Q-L) is an open-source relational database management system

POSTGRESQL INIT COMMANDS :

sudo service postgresql start

psql -U postgres

CREATE DATABASE devs;
[DON'T MISS semicolon ; ]

List of databases
   Name    |  Owner   | Encoding | Collate |  Ctype  |   Access privileges

-----------+----------+----------+---------+---------+-----------------------
 devs      | postgres | UTF8     | C.UTF-8 | C.UTF-8 |
 postgres  | postgres | UTF8     | C.UTF-8 | C.UTF-8 |
 template0 | postgres | UTF8     | C.UTF-8 | C.UTF-8 | =c/postgres          +
           |          |          |         |         | postgres=CTc/postgres
 template1 | postgres | UTF8     | C.UTF-8 | C.UTF-8 | =c/postgres          +
           |          |          |         |         | postgres=CTc/postgres
(4 rows)

|mark: ...skipping...

CREATE DATABASE backendclass;

postgres=# DROP DATABASE backendclass;

DROP DATABASE

postgres=# \c devs

TO CONNECT TO devs databse 🔰 You are now connected to database "devs" as user "postgres".

devs=# CREATE TABLE COMPANY(

devs(# ID INT NOT NULL,

devs(# NAME CHAR[50],

devs(# AGE INT,

devs(# ADDRESS TEXT

devs(# );

CREATE TABLE

devs=# \d

\d means display👀

Also, Table name is case insensitive here

  List of relations
 Schema |  Name   | Type  |  Owner
--------+---------+-------+----------
 public | company | table | postgres
(1 row)

devs=# \d COMPANY
                  Table "public.company"
 Column  |      Type      | Collation | Nullable | Default
---------+----------------+-----------+----------+---------
 id      | integer        |           | not null |
 name    | character(1)[] |           |          |
 age     | integer        |           |          |
 address | text           |           |          |

devs=# DROP TABLE COMPANY;

DROP TABLE

devs=# \d company

MEANS TABLE COMPANY IS DELETED NOW 👍

Did not find any relation named "company".

postgres01.PNG

postgres02.PNG