CopyFrom doesn't allow options to be passed in

[forge33]

The current version of CopyFrom doesn't allow us to pass in any options to influence the copy command. Postgres has a variety of options that can be configured during a copy call but we can't specify any of these while executing CopyFrom.

While this generally isn't a problem, while using Yugabyte as a database, there are some options that we need passed.

Currently we use a fork of pgx v5.0.2 but it would be nice to finally use the latest without having to maintain this extra code.

We've done it by introducing a new method CopyFromWithOptions which allows some options to be configured. While ours has a static list of options set, we'd probably need it to be a bit more flexible for this repo.

[jackc]

I'm interested in supporting more CopyFrom features. However, I have not yet figured out an interface I am happy with. See #1369 (comment) for some of the options. Also, see #2190 and #1369.

[forge33]

I think that #1369 (comment) is a good start. I think the idea is that we can take the stock postgres copy from options and then allow for further expansion(in the case of yugabyte which takes extended options)
So to add to your comment:

• Add a new function such as CopyFromWithOptions
• This function could also take a string to be added to the WHERE clause, as to not get too complicated
• This function can take a variadic options argument for stock postgres options, plus an additional map for options which aren't part of stock postgres such as yugabyte's options. Both to be appended to the WITH clause
• Modify CopyFrom to call CopyFromWithOptions with no options defined to maintain compatibility