Hi, On 2014-09-18 02:14:48 -0500, Michael Paquier wrote: > As there has been a dump of CATALOG_VERSION_NO on REL9_4_STABLE > recently, I am coming back to the options OUTPUT_PLUGIN_* that are > rather confusing for developers of decoder plugins. In short, when > extracting changes from a replication slot, a decoder plugin is free > to set one option that influences the output that is fetched by a > logical receiver: OUTPUT_PLUGIN_TEXTUAL_OUTPUT or > OUTPUT_PLUGIN_BINARY_OUTPUT. The interesting point about this format > option is that it does not directly influence the changes generated by > an output plugin: its value only has effect on the set of functions > pg_logical_[get|peek]_[binary_|]changes that can be used by a > non-replication connection to get individual changes from a repslot. > > So a receiver fetching changes using PQgetCopyData is not really > impacted by this format option. Even better it is even possible to use > a custom option that is part of output_plugin_options to switch the > OUTPUT_PLUGIN_* value (cf option force-binary in > contrib/test_decoding). > > My point is: logical decoding is presenting in its infrastructure API > a format option that could be added as a custom option in a decoder > plugin. Isn't that orthogonal? To illustrate this argument here is an > example: we could remove force-binary in test_decoding and replace it > by a option that allows the user to directly choose the output format, > like format=[binary|textual] and do the conversion in the plugin. In > the same manner, the functions pg_logical_[get|peek]_binary_changes > are equivalent to their cousin pg_logical_[get|peek]_changes casted to > bytea.
The point is that operating with byteas on SQL level is freaking painful. > I am raising this point before the 9.4 ship sails, thinking long-term > and to faciliate the maintenance of existing code. Attached is a patch > that simplifies the current logical decoding API regarding that. Sorry, -1. Improving the docs here is on my roadmap, but I don't see the benefit of this. Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
