diff options
Diffstat (limited to 'src/backend/parser/parse_clause.c')
| -rw-r--r-- | src/backend/parser/parse_clause.c | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/src/backend/parser/parse_clause.c b/src/backend/parser/parse_clause.c index 939fa834e0..87b0c8fd41 100644 --- a/src/backend/parser/parse_clause.c +++ b/src/backend/parser/parse_clause.c @@ -2011,6 +2011,20 @@ transformDistinctClause(ParseState *pstate, true); } + /* + * Complain if we found nothing to make DISTINCT. Returning an empty list + * would cause the parsed Query to look like it didn't have DISTINCT, with + * results that would probably surprise the user. Note: this case is + * presently impossible for aggregates because of grammar restrictions, + * but we check anyway. + */ + if (result == NIL) + ereport(ERROR, + (errcode(ERRCODE_SYNTAX_ERROR), + is_agg ? + errmsg("an aggregate with DISTINCT must have at least one argument") : + errmsg("SELECT DISTINCT must have at least one column"))); + return result; } @@ -2115,6 +2129,11 @@ transformDistinctOnClause(ParseState *pstate, List *distinctlist, true); } + /* + * An empty result list is impossible here because of grammar restrictions. + */ + Assert(result != NIL); + return result; } |