Generate uuid for all records in a table PostgreSQL

1. Enable the uuid-ossp extension (if not already enabled):

   CREATE EXTENSION IF NOT EXISTS "uuid-ossp";

2. Add a UUID column to your table:

   Let's assume you have a table called my_table and you want to add a UUID column named uuid_column. You can use the following SQL command to add the column:

   ALTER TABLE my_table
   ADD COLUMN uuid_column UUID DEFAULT uuid_generate_v4();

   This command adds a new column to your table with default values generated using the uuid_generate_v4() function.

3. Update existing rows with UUID values:

   To populate the newly added UUID column with UUIDs for all existing rows, you can use an UPDATE statement:

   UPDATE my_table
   SET uuid_column = uuid_generate_v4();

   This statement will generate a UUID for each row in your table and update the uuid_column with those values.

4. Optional: Make the UUID column not nullable (if needed):

   By default, the UUID column will allow NULL values. If you want to enforce that the UUID column cannot be NULL, you can use the following SQL command:

   ALTER TABLE my_table
   ALTER COLUMN uuid_column SET NOT NULL;