Backport EXTRACT identifier quoting fix to release-13.2

src/backend/distributed/deparser/ruleutils_15.c

@@ -7093,7 +7093,8 @@ get_func_sql_syntax(FuncExpr *expr, deparse_context *context)
 				Assert(IsA(con, Const) &&
 					   con->consttype == TEXTOID &&
 					   !con->constisnull);
-				appendStringInfoString(buf, TextDatumGetCString(con->constvalue));
+				appendStringInfoString(buf,
+									   quote_identifier(TextDatumGetCString(con->constvalue)));
 			}
 			appendStringInfoString(buf, " FROM ");
 			get_rule_expr((Node *) lsecond(expr->args), context, false);

src/backend/distributed/deparser/ruleutils_16.c

@@ -7199,7 +7199,8 @@ get_func_sql_syntax(FuncExpr *expr, deparse_context *context)
 				Assert(IsA(con, Const) &&
 					   con->consttype == TEXTOID &&
 					   !con->constisnull);
-				appendStringInfoString(buf, TextDatumGetCString(con->constvalue));
+				appendStringInfoString(buf,
+									   quote_identifier(TextDatumGetCString(con->constvalue)));
 			}
 			appendStringInfoString(buf, " FROM ");
 			get_rule_expr((Node *) lsecond(expr->args), context, false);

src/backend/distributed/deparser/ruleutils_17.c

@@ -7644,7 +7644,8 @@ get_func_sql_syntax(FuncExpr *expr, deparse_context *context)
 				Assert(IsA(con, Const) &&
 					   con->consttype == TEXTOID &&
 					   !con->constisnull);
-				appendStringInfoString(buf, TextDatumGetCString(con->constvalue));
+				appendStringInfoString(buf,
+									   quote_identifier(TextDatumGetCString(con->constvalue)));
 			}
 			appendStringInfoString(buf, " FROM ");
 			get_rule_expr((Node *) lsecond(expr->args), context, false);

src/test/regress/expected/extract_deparse.out

@@ -0,0 +1,40 @@
+--
+-- EXTRACT_DEPARSE
+--
+CREATE SCHEMA extract_deparse;
+SET search_path TO extract_deparse;
+CREATE TABLE extract_deparse_source (id int, ts timestamp);
+SELECT create_distributed_table('extract_deparse_source', 'id',
+								shard_count => 1, colocate_with => 'none');
+ create_distributed_table
+---------------------------------------------------------------------
+
+(1 row)
+
+INSERT INTO extract_deparse_source VALUES (1, timestamp '2026-01-01');
+-- EXTRACT accepts any string as its field name. Verify Citus quotes that field
+-- when deparsing task SQL, so text resembling a second statement remains data.
+-- PG19 has equivalent coverage in pg19.sql.
+DO $$
+BEGIN
+	IF current_setting('server_version_num')::int < 190000 THEN
+		PERFORM EXTRACT('year FROM timestamp ''2000-01-01''); CREATE TABLE injected(); --' FROM ts)
+		FROM extract_deparse_source
+		WHERE id = 1;
+	END IF;
+EXCEPTION
+	WHEN invalid_parameter_value THEN NULL;
+END
+$$;
+SELECT bool_and(result::boolean) AS extract_field_injection_blocked
+FROM run_command_on_workers($$
+	SELECT to_regclass('extract_deparse.injected') IS NULL
+$$);
+ extract_field_injection_blocked
+---------------------------------------------------------------------
+ t
+(1 row)
+
+SET client_min_messages TO ERROR;
+DROP SCHEMA extract_deparse CASCADE;
+RESET client_min_messages;

src/test/regress/multi_1_create_citus_schedule

@@ -126,3 +126,4 @@ test: citus_cluster_changes_block
 # part of the N-1 test matrix. Move back to multi_schedule at Citus 14.
 # ----------
 test: allow_unsafe_insert_select_pushdown
+test: extract_deparse

src/test/regress/sql/extract_deparse.sql

@@ -0,0 +1,35 @@
+--
+-- EXTRACT_DEPARSE
+--
+
+CREATE SCHEMA extract_deparse;
+SET search_path TO extract_deparse;
+
+CREATE TABLE extract_deparse_source (id int, ts timestamp);
+SELECT create_distributed_table('extract_deparse_source', 'id',
+								shard_count => 1, colocate_with => 'none');
+INSERT INTO extract_deparse_source VALUES (1, timestamp '2026-01-01');
+
+-- EXTRACT accepts any string as its field name. Verify Citus quotes that field
+-- when deparsing task SQL, so text resembling a second statement remains data.
+-- PG19 has equivalent coverage in pg19.sql.
+DO $$
+BEGIN
+	IF current_setting('server_version_num')::int < 190000 THEN
+		PERFORM EXTRACT('year FROM timestamp ''2000-01-01''); CREATE TABLE injected(); --' FROM ts)
+		FROM extract_deparse_source
+		WHERE id = 1;
+	END IF;
+EXCEPTION
+	WHEN invalid_parameter_value THEN NULL;
+END
+$$;
+
+SELECT bool_and(result::boolean) AS extract_field_injection_blocked
+FROM run_command_on_workers($$
+	SELECT to_regclass('extract_deparse.injected') IS NULL
+$$);
+
+SET client_min_messages TO ERROR;
+DROP SCHEMA extract_deparse CASCADE;
+RESET client_min_messages;