Michel Pelletier <pelletier.michel@xxxxxxxxx> writes: > It mentions "on disk" does this mean the flattened representation must be > binary compatible with what matrix_send emits? They will likely be the > same now, so I can see this as a convenience, but is it a requirement? No, your on-the-wire representation for send/recv can be different from what you put on-disk. In fact, typically I'd recommend that it *should* be different to some extent, to insulate COPY BINARY data from internal representation choices and simplify any client code that might look at the "binary" format. See for example numeric_send/recv, which don't just transmit the internal format as-is --- and that was a good thing because it let us implement various storage optimizations over the years without breaking COPY BINARY compatibility. It's also a good idea to try to make the on-the-wire representation independent of server endianness and alignment rules. The point of the comment you're looking at is that the "flat" varlena representation that you have to translate to/from is the same as what will be on-disk if the datum gets stored someplace. regards, tom lane
