psql: Add tab completion for DELETE ... USING.

This implements the tab completion that was marked as XXX TODO in the
source code. The following completion is now supported:

    DELETE FROM <table> USING <TAB> -> list of relations supporting SELECT

This uses Query_for_list_of_selectables (instead of Query_for_list_of_tables)
because the USING clause can reference not only tables but also views and
other selectable objects, following the same syntax as the FROM clause
of a SELECT statement.

Author: Tatsuya Kawata <kawatatatsuya0913@gmail.com>
Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Reviewed-by: Kirill Reshke <reshkekirill@gmail.com>
Reviewed-by: Soumya S Murali <soumyamurali.work@gmail.com>
Reviewed-by: Fujii Masao <masao.fujii@gmail.com>
Discussion: https://postgr.es/m/CAHza6qf0CLJuJr+5cQw0oWNebM5VyMB-ghoKBgnEjOQ_JtAiuw@mail.gmail.com

diff --git a/src/bin/psql/tab-complete.in.c b/src/bin/psql/tab-complete.in.c
index b2dba6d10ab94074ea91857331320627af23fa00..43451fce1c3709921bf21edba84609cdc7cd6e91 100644 (file)
--- a/src/bin/psql/tab-complete.in.c
+++ b/src/bin/psql/tab-complete.in.c
@@ -4266,7 +4266,9 @@ match_previous_words(int pattern_id,
        /* Complete DELETE FROM <table> */
        else if (TailMatches("DELETE", "FROM", MatchAny))
                COMPLETE_WITH("USING", "WHERE");
-       /* XXX: implement tab completion for DELETE ... USING */
+       /* Complete DELETE FROM <table> USING with relations supporting SELECT */
+       else if (TailMatches("DELETE", "FROM", MatchAny, "USING"))
+               COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_selectables);
 
 /* DISCARD */
        else if (Matches("DISCARD"))