I would like to copy two tables from database A to database B, in postgres
how can I do it using pg_dump without losing the previous tables and data in database B ?
I read some answers in Stack Overflow suggesting using pg_dump but in the documentation page I read?
The idea behind this dump method is to generate a text file with SQL
commands that, when fed back to the server, will recreate the database
in the same state as it was at the time of the dump
Doesn't that mean it will delete the previous data in database B?
If someone could tell me step by step solution to move two tables in database A to database B without losing any previous data in Database B, it would be helpful.
I found the answer to my question :
sudo -u OWNER_USER pg_dump -t users databasename1 | sudo -u OWNER_USER psql databasename2
if you pg_restore a database into b database, of course a will replace b. instead pick specific table you would like to restore using pg_restore -t
you could pg_restore to different schema, by using -O (no_owner)
so let say
pg_dump -Fc -f dump.dmp -v -h host -U user_login -n schema_to_dump
you can
pg_restore -v -h host -U user_login -n schema_to_import -a --disable-triggers dump.dmp
Related
After making some schema change in table message in postgresql 13 database, the table is backed up in pgadmin4 in a file named message.sql. The schema change needs to be populated in another database. What I did is to drop the table message in that database. But I have hard time to re-create table message from the backup file messages.sql (not using CREATE table message ....). I use pg_restore to restore data but was not successful for re-creating table schema. Here is command I tried with no luck:
pg_restore --data-only -h localhost -U postgres -W -d dynamo -t messages /home/download/messages.sql
pg_restore --clean -h localhost -U postgres -W -d dynamo -t messages /home/download/messages.sql
I also tried to create an blank table (no column) called messages in the database and repeated above command, again without luck.
Here is how a new table is added to the current database:
backup the current db on the server with pg_dump
create the new database on dev PC with addition of new table
On dev PC, use pgadmin to restore the backup file in step 1 to new database created in step 2.
backup in pgadmin and create a .backup file for db in step 3.
on server, use pg_restore to overwrite the current db with new database backup file created in step 4:
pg_restore --clean -U postgres --dbname=mydb -W -h localhost --verbose /home/download/mydb.backup
open psql terminal to verify the new table
Need Help !!
While i'm going to restore a partition table using :
pg_restore -U (username) -d (Database) -p (port_number) -t (partition_table) -f (filename)
the result is success but the data in that partition table is not restored, can anyone help me ?
When -t is specified, pg_restore makes no attempt to dump any other database objects that the selected table(s) might depend upon. Therefore, there is no guarantee that the results of a specific-partitioned table dump can be successfully restored
However you can take dump using
pg_dump --host=hostname --username=user -t "child_table_*" --data-only --file=dump_out.sql dbname
and then restore it, This is probably a consequence of the design decision to have partitions visible as individual tables on the SQL level.
please refer:
https://www.postgresql.org/docs/13/app-pgrestore.html
https://www.postgresql.org/docs/11/app-pgdump.html
I'm having some issue with my migrations in Heroku. I've tried several things but none seem to work.
I feel like I should just drop the table that's causing the issue, which will delete all the data in production.
If I drop the table, and re-created the table, will I be able to restore all of the data I lost? Because I will backup my database on Heroku before I drop the table.
Thanks!
You should run a backup with
pg_dump -h hostname -p 5432 -U username -F c -t mytable -f dumpfile mydatabase
Then, after you have dropped and re-created the table, you can restore the data with
pg_restore -h hostname -p 5432 -U username -a -d mydatabase dumpfile
However, this will not work if the table structure has changed.
In that case, you might want to use COPY directly to write the data to a file and restore them from there.
Let's for example assume you plan to add another column. Then you could dump with
COPY (SELECT *, NULL FROM mytable) TO '/file/on/dbserver';
After the table was created with the new column, you can
COPY mytable FROM '/file/on/dbserver';
The new column will be filled with the NULL values.
Modify this basic recipe for more fancy requirements.
I am having some difficulties with restoring the schema of a table. I dumped my Heroku Postgres db and I used pg_restore to restore one table from it into my local db (it has more than 20 tables). It was successfully restored, but I was having issues when I tried to insert new data into the table.
When I opened up my database using psql, I found out that the restored table is available with all the data, but its schema has zero rows. Is there anyway I could import both the table and its schema from the dump? Thank you very much.
This is how I restored the table into my local db:
pg_restore -U postgres --dbname my_db --table=message latest.dump
Edit:
I tried something like this following the official docs, but it just gets blocked and nothing happened. My db is small, no more than a couple of megabytes and the table's schema I am trying to restore has no more than 100 row.
pg_restore -U postgres --dbname mydb --table=message --schema=message_id_seq latest.dump
As a more general answer (I needed to restore a single table from a huge backup), you may want to take a look at this post: https://thequantitative.medium.com/restoring-individual-tables-from-postgresql-pg-dump-using-pg-restore-options-ef3ce2b41ab6
# run the schema-only restore as root
pg_restore -U postgres --schema-only -d new_db /directory/path/db-dump-name.dump
# Restore per table data using something like
pg_restore -U postgres --data-only -d target-db-name -t table_name /directory/path/dump-name.dump
From the Heroku DevCenter here
Heroku Postgres is integrated directly into the Heroku CLI and offers
many helpful commands that simplify common database tasks
You can check here if your environment is correctly configured.
In this way, you can use the Heroku CLI pg:pull command to pull remote data from a Heroku Postgres database to a local database on your machine.
For example:
$ heroku pg:pull HEROKU_POSTGRESQL_MAGENTA mylocaldb --app sushi
I am trying to copy a table from one database to another database But no response in server
Here is the command
pg_dump -U database_user_name -t categories my_current_db_name | psql new_db_name
What wrong in the above code it is not showing any response.
If something does not work then divide it into smaller problems.
At first try to run:
pg_dump -U database_user_name -t categories my_current_db_name
What is it printing? Do you see error message or correct dump output?
Then try to run:
psql new_db_name
Is it able to connect to database?
Possible problems:
new_db_name does not exists
you cannot connect with source or destination database because of wrong user/password/db host/port