Executive summary: There is now a CommandDeparse_hook; deparse_utility_command is provided as an extension, intended for 9.6; rest of patch would be pushed to 9.5.
Long version: I've made command deparsing hookable. Attached there are three patches: the first patch contains changes to core that just add the "command list" stuff, so that on ddl_command_end there is access to what has been executed. This includes the OID of the object just created, the command tag, and assorted other details; the deparsed command in JSON format is not immediately part of the result. The third patch contains all the deparse code, packaged as a contrib module and extension named ddl_deparse. Essentially, it's everything that was previously in tcop/deparse_utility.c and utils/adt/ddl_json.c: the stuff that takes the parsenode and OID of a command execution and turns it into a JSON blob, and also the support function that takes the JSON blob and converts back into the plain text rendering of the command. The second patch contains some changes to core code that support the ddl_deparse extension; mainly some ruleutils.c changes. What links patches 0001 and 0003 is a hook, CommandDeparse_hook. If unset, the pg_event_trigger_ddl_commands function returns some boilerplate text like "no deparse function installed"; if the extension is installed, the JSON rendering is returned instead and can be used with the ddl_deparse_expand_command() function. The rationale for doing things this way is that it will be useful to have 9.5 expose the pg_event_trigger_ddl_commands() function for various uses, while we refine the JSON bits some more and get it committed for 9.6. In reviews, it's clear that there's some more bits to fiddle so that it can be as general as possible. I think we should label the whole DDL command reporting as experimental in 9.5 and subject to change, so that we can just remove the hook in 9.6 when the ddl_deparse thing becomes part of core. Thoughts? -- Álvaro Herrera http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers