From: Robert Haas <rhaas@postgresql.org>
Date: Fri, 12 Dec 2025 17:22:08 +0000 (-0500)
Subject: Ban zero-length delimited identifiers.
X-Git-Url: http://git.postgresql.org/gitweb/static/gitweb.%3Cscript%20data-cfasync=?a=commitdiff_plain;h=ebff01be75e80fc02916f583555b2d11d27a6d4c;p=users%2Frhaas%2Fpostgres.git

Ban zero-length delimited identifiers.
---

diff --git a/contrib/pg_plan_advice/expected/syntax.out b/contrib/pg_plan_advice/expected/syntax.out
index 36200c8935..eec0298089 100644
--- a/contrib/pg_plan_advice/expected/syntax.out
+++ b/contrib/pg_plan_advice/expected/syntax.out
@@ -84,6 +84,12 @@ DETAIL:  Could not parse advice: syntax error at end of input
 SET pg_plan_advice.advice = 'SEQ_SCAN("';
 ERROR:  invalid value for parameter "pg_plan_advice.advice": "SEQ_SCAN(""
 DETAIL:  Could not parse advice: unterminated quoted identifier at end of input
+SET pg_plan_advice.advice = 'SEQ_SCAN("")';
+ERROR:  invalid value for parameter "pg_plan_advice.advice": "SEQ_SCAN("")"
+DETAIL:  Could not parse advice: zero-length delimited identifier at or near """
+SET pg_plan_advice.advice = 'SEQ_SCAN("a"';
+ERROR:  invalid value for parameter "pg_plan_advice.advice": "SEQ_SCAN("a""
+DETAIL:  Could not parse advice: syntax error at end of input
 SET pg_plan_advice.advice = 'SEQ_SCAN(#';
 ERROR:  invalid value for parameter "pg_plan_advice.advice": "SEQ_SCAN(#"
 DETAIL:  Could not parse advice: syntax error at or near "#"
diff --git a/contrib/pg_plan_advice/pgpa_scanner.l b/contrib/pg_plan_advice/pgpa_scanner.l
index be7d7ba13a..c49b29d906 100644
--- a/contrib/pg_plan_advice/pgpa_scanner.l
+++ b/contrib/pg_plan_advice/pgpa_scanner.l
@@ -189,6 +189,9 @@ xcinside		[^*/]+
 
 <xd>{xdstop}	{
 					BEGIN(INITIAL);
+					if (yyextra->litbuf.len == 0)
+						pgpa_yyerror(result, parse_error_msg_p, yyscanner,
+									 "zero-length delimited identifier");
 					yylval->str = pstrdup(yyextra->litbuf.data);
 					return TOK_IDENT;
 				}
diff --git a/contrib/pg_plan_advice/sql/syntax.sql b/contrib/pg_plan_advice/sql/syntax.sql
index 5f86ecf43b..0692dc895c 100644
--- a/contrib/pg_plan_advice/sql/syntax.sql
+++ b/contrib/pg_plan_advice/sql/syntax.sql
@@ -26,6 +26,8 @@ SET pg_plan_advice.advice = 'SEQUENTIAL_SCAN(x)';
 SET pg_plan_advice.advice = 'SEQ_SCAN';
 SET pg_plan_advice.advice = 'SEQ_SCAN(';
 SET pg_plan_advice.advice = 'SEQ_SCAN("';
+SET pg_plan_advice.advice = 'SEQ_SCAN("")';
+SET pg_plan_advice.advice = 'SEQ_SCAN("a"';
 SET pg_plan_advice.advice = 'SEQ_SCAN(#';
 SET pg_plan_advice.advice = '()';
 SET pg_plan_advice.advice = '123';