Adjust assorted hint messages that list all valid options.

Instead of listing all valid options, we now try to provide one
that looks similar.  Since this may be useful elsewhere, this
change introduces a new set of functions that can be reused for
similar purposes.

Author: Nathan Bossart <nathandbossart@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/b1f9f399-3a1a-b554-283f-4ae7f34608e2@enterprisedb.com

1 files changed, 14 insertions, 9 deletions

diff --git a/contrib/postgres_fdw/option.c b/contrib/postgres_fdw/option.c
index 95dde056eba..fa80ee2a55e 100644
--- a/contrib/postgres_fdw/option.c
+++ b/contrib/postgres_fdw/option.c
@@ -90,26 +90,31 @@ postgres_fdw_validator(PG_FUNCTION_ARGS)
 		{
 			/*
 			 * Unknown option specified, complain about it. Provide a hint
-			 * with list of valid options for the object.
+			 * with a valid option that looks similar, if there is one.
 			 */
 			PgFdwOption *opt;
-			StringInfoData buf;
+			const char *closest_match;
+			ClosestMatchState match_state;
+			bool		has_valid_options = false;
 
-			initStringInfo(&buf);
+			initClosestMatch(&match_state, def->defname, 4);
 			for (opt = postgres_fdw_options; opt->keyword; opt++)
 			{
 				if (catalog == opt->optcontext)
-					appendStringInfo(&buf, "%s%s", (buf.len > 0) ? ", " : "",
-									 opt->keyword);
+				{
+					has_valid_options = true;
+					updateClosestMatch(&match_state, opt->keyword);
+				}
 			}
 
+			closest_match = getClosestMatch(&match_state);
 			ereport(ERROR,
 					(errcode(ERRCODE_FDW_INVALID_OPTION_NAME),
 					 errmsg("invalid option \"%s\"", def->defname),
-					 buf.len > 0
-					 ? errhint("Valid options in this context are: %s",
-							   buf.data)
-					 : errhint("There are no valid options in this context.")));
+					 has_valid_options ? closest_match ?
+					 errhint("Perhaps you meant the option \"%s\".",
+							 closest_match) : 0 :
+					 errhint("There are no valid options in this context.")));
 		}
 
 		/*