Don't use ctid scan for negative relpages (like during scanning a partitioned table).

src/include/postgres_scanner.hpp

@@ -84,7 +84,7 @@ class PostgresScanFunction : public TableFunction {
 	PostgresScanFunction();
 
 	static void PrepareBind(PostgresVersion version, ClientContext &context, PostgresBindData &bind,
-	                        idx_t approx_num_pages);
+	                        int64_t approx_num_pages);
 };
 
 class PostgresScanFunctionFilterPushdown : public TableFunction {

src/include/storage/postgres_table_entry.hpp

@@ -35,7 +35,7 @@ struct PostgresTableInfo {
 	unique_ptr<CreateTableInfo> create_info;
 	vector<PostgresType> postgres_types;
 	vector<string> postgres_names;
-	idx_t approx_num_pages = 0;
+	int64_t approx_num_pages = 0;
 };
 
 class PostgresTableEntry : public TableCatalogEntry {
@@ -64,7 +64,7 @@ class PostgresTableEntry : public TableCatalogEntry {
 	//! We would in this case remap them to "ID" and "id:1", while postgres_names store the original names
 	vector<string> postgres_names;
 	//! The approximate number of pages a table consumes in Postgres
-	idx_t approx_num_pages;
+	int64_t approx_num_pages;
 };
 
 } // namespace duckdb

src/postgres_scanner.cpp

@@ -107,7 +107,7 @@ static void PostgresGetSnapshot(ClientContext &context, PostgresVersion version,
 }
 
 void PostgresScanFunction::PrepareBind(PostgresVersion version, ClientContext &context, PostgresBindData &bind_data,
-                                       idx_t approx_num_pages) {
+                                       int64_t approx_num_pages) {
 	Value pages_per_task;
 	if (context.TryGetCurrentSetting("pg_pages_per_task", pages_per_task)) {
 		bind_data.pages_per_task = UBigIntValue::Get(pages_per_task);
@@ -130,10 +130,14 @@ void PostgresScanFunction::PrepareBind(PostgresVersion version, ClientContext &c
 		// see https://github.com/duckdb/postgres_scanner/issues/186
 		use_ctid_scan = false;
 	}
+	if (approx_num_pages < 0) {
+		// negative relpages (e.g. partitioned tables) cannot use ctid scan
+		use_ctid_scan = false;
+	}
 	if (!use_ctid_scan) {
 		approx_num_pages = 0;
 	}
-	bind_data.SetTablePages(approx_num_pages);
+	bind_data.SetTablePages(static_cast<idx_t>(approx_num_pages));
 	bind_data.version = version;
 	if (version.type_v == PostgresInstanceType::REDSHIFT) {
 		bind_data.use_text_protocol = true;

src/storage/postgres_table_set.cpp

@@ -128,9 +128,8 @@ void PostgresTableSet::CreateEntries(PostgresTransaction &transaction, PostgresR
 			if (info) {
 				tables.push_back(std::move(info));
 			}
-			auto approx_num_pages = result.IsNull(row, 2) ? 0 : result.GetInt64(row, 2);
 			info = make_uniq<PostgresTableInfo>(schema, table_name);
-			info->approx_num_pages = approx_num_pages;
+			info->approx_num_pages = result.IsNull(row, 2) ? 0 : result.GetInt64(row, 2);
 		}
 		AddColumnOrConstraint(&transaction, &schema, result, row, *info);
 	}
@@ -169,7 +168,7 @@ unique_ptr<PostgresTableInfo> PostgresTableSet::GetTableInfo(PostgresTransaction
 	for (idx_t row = 0; row < rows; row++) {
 		AddColumnOrConstraint(&transaction, &schema, *result, row, *table_info);
 	}
-	table_info->approx_num_pages = result->GetInt64(0, 2);
+	table_info->approx_num_pages = result->IsNull(0, 2) ? 0 : result->GetInt64(0, 2);
 	return table_info;
 }
 
@@ -185,7 +184,7 @@ unique_ptr<PostgresTableInfo> PostgresTableSet::GetTableInfo(ClientContext &cont
 	for (idx_t row = 0; row < rows; row++) {
 		AddColumnOrConstraint(nullptr, nullptr, *result, row, *table_info);
 	}
-	table_info->approx_num_pages = result->GetInt64(0, 2);
+	table_info->approx_num_pages = result->IsNull(0, 2) ? 0 : result->GetInt64(0, 2);
 	return table_info;
 }
 

test/other.sql

@@ -168,3 +168,10 @@ create table tbl_with_unique_constraints(pk int unique, c1 int not null, c2 int,
 create schema main;
 create table main.main_tbl(i int);
 insert into main.main_tbl values (42), (NULL);
+
+-- partitioned table (parent has relpages=-1 after analyze)
+create table part_tbl (id int, val text) partition by range (id);
+create table part_tbl_1 partition of part_tbl for values from (1) to (100);
+create table part_tbl_2 partition of part_tbl for values from (100) to (200);
+insert into part_tbl values (1,'a'),(50,'b'),(100,'c'),(150,'d');
+analyze part_tbl;

test/sql/scanner/partitioned_table.test

@@ -0,0 +1,23 @@
+# name: test/sql/scanner/partitioned_table.test
+# description: Scanning a partitioned table fallbacks to 0 estimate
+# group: [scanner]
+
+require postgres_scanner
+
+require-env POSTGRES_TEST_DATABASE_AVAILABLE
+
+statement ok
+ATTACH 'dbname=postgresscanner' AS s (TYPE POSTGRES)
+
+query IT
+SELECT * FROM s.public.part_tbl ORDER BY id
+----
+1	a
+50	b
+100	c
+150	d
+
+query II
+EXPLAIN SELECT * FROM s.public.part_tbl
+----
+physical_plan	<REGEX>:.*~0 rows.*