Drop Down MenusCSS Drop Down MenuPure CSS Dropdown Menu

PostgresqlDBA interview questions and answers

-

Questions :I have three  tables which contains around 20millions of records. I am planning to update these three tables for all records. Could you suggest me best approaches to meet this, please?
Ans:
1.I think disable index before update ? And autovacuum off,arhvive off if possible.
2.Increase the check point time out
Increase shared buffer or wall beffer if archive enable.
3.Check any parallel option is there.

Comments

Post a Comment

Popular posts from this blog

Ora2PG - Oracle/MySQL to Postgres DB migration Version 20.0

-
Ora2Pg is a free tool used to  migrate  an  Oracle  or MySQL database to a  PostgreSQL  compatible schema. It connects your  Oracle  database, scan it automatically and extracts its structure or data, it then generates SQL scripts that you can load into your  PostgreSQL  database. ora2pg version 20.0 software : ora2pg-20.0.tar ora2pg-20.0   https://github.com/darold/ora2pg/releases/tag/v20.0 Some Blogs about DB Migration : https://2ndquadrant.in/postgresmigration/oracle-to-postgresql-migration/ https://2ndquadrant.in/database-migration-from-oracle-to-postgres/ INSTALLATION All Perl modules can always be found at CPAN ( http://search.cpan.org/ ). Just type the full name of the module (ex: DBD::Oracle) into the search input box, it will brings you the page for download. Releases of Ora2Pg stay at SF.net ( https://sourceforge.net/projects/ora2pg/ ). Under Windows you should install Strawberry Perl ( http://strawberryperl.com/ ) and the OSes corresponding Oracle clients. I
Read more

spfile and pfile errors

-
SQL> create pfile='/home/oracle/karan/admin/pfile/initclone.ora' from spfile; create pfile='/home/oracle/karan/admin/pfile/initclone.ora' from spfile * ERROR at line 1: ORA-01565: error in identifying file '?/dbs/spfile@.ora' ORA-27037: unable to obtain file status Linux Error: 2: No such file or directory Additional information: 3 SQL> show parameter spfile; NAME                                 TYPE        VALUE ------------------------------------ ----------- ------------------------------ spfile                               string SQL> create spfile=   2   SQL> create spfile='/home/oracle/karan/admin/pfile/initclone.ora' from pfile; create spfile='/home/oracle/karan/admin/pfile/initclone.ora' from pfile * ERROR at line 1: ORA-01078: failure in processing system parameters LRM-00109: could not open parameter file '/oraeng/app/oracle/product/11.2.0/dbs/initkiruba.ora' SQL> create spfile from pfile; create spfile from pfil
Read more

How to find the server is whether standby (slave) or primary(master) in Postgresql replication ?

-
Method 1 You can check the mode of the server using "pg_controldata". [pgsql@test~]$ pg_controldata /usr/local/pgsql/data84/ Database cluster state: in archive recovery --> This is Standby Database Database cluster state: in production --> This is Production Database [Master] Method 2 You can use pg_is_in_recovery() which returns True if recovery is still in progress(so the server is running in standby mode or slave) postgres=# select pg_is_in_recovery(); pg_is_in_recovery ------------------- t (1 row) If Return    false   so the server is running in primary mode or master postgres=# select pg_is_in_recovery(); pg_is_in_recovery ------------------- f (1 row)
Read more

PostgreSQL New version upgrade

-
Image
In this blog we are going to upgrade the postgresql server from 9.5 to 11.3 . We are upgraded the postgres server by using pg_upgrade utility as well as logical backup method , you can follow anyone  of the method . Collect the server details before proceed  upgrade activity.  Title PostgreSQL VERSION 9.5 PostgreSQL VERSION 11.3 DATA DIRECTORY /data_9.5 /data_11.3 BIN path /opt/postgresql/9.5 /opt/postgresql/11.3 PORT 50000 5432 PREREQUEST : =========== Step 1. Check the application backend connection if any application connected , Disconnect the application from DB server. Below command will be helpful to checking backend connection : template1=# select datname, count(*) from pg_stat_activity group by datname; datname | count -----------+------- testdb | 1 template1 | 0 (2 rows) template1=# select datname, numbackends from pg_stat_database; datname | numbackends -----------+------------- testdb | 1 template1 | 0 templ
Read more

How to Return a Result Set from a PostgreSQL Stored Procedure

-
Image
Both stored procedures and user-defined functions are created with CREATE FUNCTION statement in PostgreSQL. To return one or more result sets (cursors in terms of PostgreSQL), you have to use  refcursor  return type. Quick Example : -- Procedure that returns a single result set (cursor) CREATE OR REPLACE FUNCTION show_cities ( ) RETURNS refcursor AS $$ DECLARE ref refcursor; -- Declare a cursor variable BEGIN OPEN ref FOR SELECT city , state FROM cities; -- Open a cursor RETURN ref; -- Return the cursor to the caller END ; $$ LANGUAGE plpgsql; Overview : Return Multiple Result Sets Cursor Lifetime Until the  end  of transaction Auto-commit Must be  off Transaction must be active so the caller can see a result set Important Note : The cursor remains open until the end of transaction, and since PostgreSQL works
Read more