# Regarding for PostgreSQL Adminitration **URL:** \ **Category:** PostgreSQL General Discussion\ **Tags:** mysql\ **Created:** [September 4, 2020, 2:36am UTC](https://forums.percona.com/t/regarding-for-postgresql-adminitration/8009 "2020-09-04T02:36:22Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![aartiyadav](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/aartiyadav/32/103_2.png) [@aartiyadav](https://forums.percona.com/u/aartiyadav)\ **Post date:** [September 4, 2020, 2:36am UTC](https://forums.percona.com/t/regarding-for-postgresql-adminitration/8009/1 "2020-09-04T02:36:22Z")
Hello All, I want to learn PostgreSQL and looking for paid/free tutorial or suggest me any online book. Can anyone help me. ---
**Author:** ![daniil.bazhenov](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/daniil.bazhenov/32/62_2.png) [@daniil.bazhenov](https://forums.percona.com/u/daniil.bazhenov)\ **Post date:** [September 9, 2020, 12:46pm UTC](https://forums.percona.com/t/regarding-for-postgresql-adminitration/8009/2 "2020-09-09T12:46:18Z")
> aartiyadav said: > > Hello All, I want to learn PostgreSQL and looking for paid/free tutorial or suggest me any online book. Can anyone help me. Try reading this book "Postgres: The First Experience".  [https://postgrespro.com/education/books/introbook](https://postgrespro.com/education/books/introbook) And of course, read the Percona blog about PostgreSQL. Even if it's not clear now, it may come in handy in the future. [https://www.percona.com/blog/category/postgresql/](https://www.percona.com/blog/category/postgresql/) ---
**Author:** ![vijaysingh](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/vijaysingh/32/1392_2.png) [@vijaysingh](https://forums.percona.com/u/vijaysingh)\ **Post date:** [September 16, 2020, 5:55am UTC](https://forums.percona.com/t/regarding-for-postgresql-adminitration/8009/3 "2020-09-16T05:55:16Z")
> [daniil.bazhenov](https://forums.percona.com/profile/daniil.bazhenov) said: > > > aartiyadav said: > > > > Hello All, I want to learn PostgreSQL and looking for paid/free tutorial or suggest me any online book. Can anyone help me. > > Try reading this book "Postgres: The First Experience".  > [https://postgrespro.com/education/books/introbook](https://postgrespro.com/education/books/introbook "Link: https://postgrespro.com/education/books/introbook") > And of course, read the Percona blog about PostgreSQL. Even if it's not clear now, it may come in handy in the future. > [https://www.percona.com/blog/category/postgresql/](https://www.percona.com/blog/category/postgresql/) For books, I would propose the same book but for the course part, I would suggest you go through with these [PostgreSQL tutorials](https://hackr.io/tutorials/learn-postgresql "Link: https://hackr.io/tutorials/learn-postgresql"). ---
**Author:** ![Nganso](https://avatars.discourse-cdn.com/v4/letter/n/9e8a1a/32.png) [@Nganso](https://forums.percona.com/u/Nganso)\ **Post date:** [September 16, 2020, 8:43am UTC](https://forums.percona.com/t/regarding-for-postgresql-adminitration/8009/4 "2020-09-16T08:43:29Z")
Hello @ll,I have 2 differents  servers A and B each of them has  databses on postgres 9.6 I will like to migrate those databses from A and B  to  server C  with postgres 12 1. I want to ask if pg\_upgrade can be used  to perform migration  databses  from Server A and B to Server C ?it not please propose me an option with average downtime. Thank you very much for your answers Nganso ---
**Author:** ![Jobin\_Augustine](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/jobin_augustine/32/1275_2.png) [@Jobin\_Augustine](https://forums.percona.com/u/Jobin_Augustine)\ **Post date:** [October 12, 2020, 10:34pm UTC](https://forums.percona.com/t/regarding-for-postgresql-adminitration/8009/5 "2020-10-12T22:34:44Z")
Hi @Nganso 1. Migration to a different host machine with an upgraded version is usually done in the following steps. 2. Setup new host as one of the standby server for existing database using PG 9.6 binary. 3. Cut-over to new host machine. but still PG 9.6 4. Do In-place upgrade from old version (PG 9.6) to new version (PG12) using pg\_upgrade hard links. Regards, Jobin ---
**Author:** ![Fernando\_Acevedo](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/fernando_acevedo/32/3287_2.png) [@Fernando\_Acevedo](https://forums.percona.com/u/Fernando_Acevedo)\ **Post date:** [April 22, 2021, 7:35am UTC](https://forums.percona.com/t/regarding-for-postgresql-adminitration/8009/7 "2021-04-22T07:35:02Z")
> [@Pmm@postgres ERROR: relation "pg\_stat\_statements" does not exist at character 753](https://forums.percona.com/t/pmm-postgres-error-relation-pg-stat-statements-does-not-exist-at-character-753/8722/5): > > That’s it! I don’t recognize if by default postgresql by default is postgres user, and the root user was created by postgres user, lol rofl Thank you for your support, we can close it now., grin grin smile