I've only taken a quick look but I don't see any regression tests, for starters, and it's not clear if this can be passed multiple times for one pg_dump run (I'd certainly hope that it could be...).
Yes, this will absolutely accept multiple options for one run, which is how I'd imagine it would typically be used.
In fact, for each table_pattern:filter_clause you provide as an option, it will apply a corresponding WHERE clause for *every* table that matches the table_pattern.
So if you happened to use a wildcard in the table_pattern, you could actually end up with multiple tables filtered by the same WHERE clause.
This will filter every table named "table_*", e.g. ["table_0", "table_1", "table_2", "table_associated"], each with "WHERE created_at >= '2018-05-01'", and it will also filter "other_table" with "WHERE id < 100".
Not sure how useful the wildcard feature is, but it matches the behavior of the other pg_dump options that specify tables, and came along for free by reusing that implementation.
Also, if you haven't already, this should be registered on the commitfest app, so we don't lose track of it.
