Using pg_restore to create or overwrite tables

Question

I know this is a weird request, but for some hacky reasons I can't avoid, I'd like to be able to consistently sync a few tables from one database to another. I know I could write out the functionality myself in a script, but I figure pg_dump and pg_restore will apply a lot of optimizations to the process that I'm not aware of myself.

What I'm wondering is if there's a way to have pg_restore overwrite the existing tables. Basically, in pseudo-code something like:

-- pseudo code
begin;
drop table to_restore;
drop table to_restore2;
drop table to_restore3;

-- etc

restore table to_restore;
restore table to_restore2;
restore table to_restore3;

-- etc
commit;

I'm also open to alternatives ways of doing this if this isn't so great.

Answer 1

Seems like you want the -c option specified in the pg_restore documentation

-c

--clean

Clean (drop) database objects before recreating them. (Unless --if-exists is used, this might generate some harmless error messages, if any objects were not present in the destination database.)

which you can use with the -1 flag to do everything in one transaction

-1

--single-transaction

Execute the restore as a single transaction (that is, wrap the emitted commands in BEGIN/COMMIT). This ensures that either all the commands complete successfully, or no changes are applied. This option implies --exit-on-error.

Answer 2

This is only example of possible solution:

copy those tables from first db to csv. and use extremely fast copy in transaction:

begin;
truncate table to_restore;
truncate table to_restore2;
truncate table to_restore3;
  set commit_delay to 100000;
  set synchronous_commit to off;
copy to_restore from 'to_restore.csv';
copy to_restore2 from 'to_restore2.csv';
copy to_restore3 from 'to_restore3.csv';
commit;