"Extendable support for custom targets"

[seigel]

The readme suggests that there is support for "Extendable support for custom targets". I was wondering if there were any examples of this around anywhere. Also, could this support streaming pg->pg (with a different schema name).

Thanks!

[kvch]

I was wondering if there were any examples of this around anywhere.

Unfortunately, we do not have a tutorial for this. The extensibility comes from using pgstream as a Go library. A target is anything implementing the Processor interface in pkg/wal/processor/wal_processor.go:

type Processor interface {
   ProcessWALEvent(ctx context.Context, walEvent *wal.Event) error
   Close() error
   Name() string
}

You get a *wal.Event (DML or DDL, plus a CommitPosition for checkpointing) and do whatever you like with it. The stdout writer (pkg/wal/processor/stdout/wal_stdout_writer.go) is the simplest reference to copy from, and targets are wired up in buildProcessor() in pkg/stream/stream.go.

could this support streaming pg->pg (with a different schema name)

Yes, it can. The Postgres target writes using the source schema name directly. The cleanest way to achieve it right now is exactly the custom-target route above: a small Processor that wraps the Postgres writer and rewrites wal.Data.Schema.