[Feature] Replace mysql with postgres

[albusshirazi]

Since Devlake now fully supports Postgres, lt is time to switch the default database image in the official helm chart from mysql into postgres!

[klesh]

Could you please elaborate on why we should switch to using PostgreSQL by default? Thank you!

[albusshirazi]

Yes, of course!
https://levelup.gitconnected.com/mysql-vs-postgresql-what-we-learned-after-switching-and-why-were-never-going-back-6079a752e7d0
In addition, Devlake is an analytics tool, and postgres is better in complex analytics then mysql - https://charleswan111.medium.com/mysql-vs-postgresql-a-comprehensive-comparison-of-features-and-use-cases-392d840aa20b
Moreover, mysql isn't good at heavy concurrent data write, and for Devlake it is important since there could be many different pipeline working at the same time.