Make non-updating queries use readonly unless there was a prior mut…

…ation (#963)

pgx-examples/schemas/src/lib.rs

@@ -100,7 +100,7 @@ mod tests {
 
     #[pg_test]
     fn test_my_some_schema_type() {
-        Spi::connect(|c| {
+        Spi::connect(|mut c| {
             // "MySomeSchemaType" is in 'some_schema', so it needs to be discoverable
             c.update("SET search_path TO some_schema,public", None, None);
             assert_eq!(

pgx-tests/src/tests/bgworker_tests.rs

@@ -25,7 +25,7 @@ pub extern "C" fn bgworker(arg: pg_sys::Datum) {
     if arg > 0 {
         BackgroundWorker::transaction(|| {
             Spi::run("CREATE TABLE tests.bgworker_test (v INTEGER);");
-            Spi::connect(|client| {
+            Spi::connect(|mut client| {
                 client.update(
                     "INSERT INTO tests.bgworker_test VALUES ($1);",
                     None,
@@ -71,7 +71,7 @@ pub extern "C" fn bgworker_return_value(arg: pg_sys::Datum) {
     };
     while BackgroundWorker::wait_latch(Some(Duration::from_millis(100))) {}
     BackgroundWorker::transaction(|| {
-        Spi::connect(|c| {
+        Spi::connect(|mut c| {
             c.update(
                 "INSERT INTO tests.bgworker_test_return VALUES ($1)",
                 None,

pgx-tests/src/tests/spi_tests.rs

@@ -186,7 +186,7 @@ mod tests {
 
     #[pg_test]
     fn test_inserting_null() -> Result<(), pgx::spi::Error> {
-        Spi::connect(|client| {
+        Spi::connect(|mut client| {
             client.update("CREATE TABLE tests.null_test (id uuid)", None, None);
         });
         assert_eq!(
@@ -202,7 +202,7 @@ mod tests {
 
     #[pg_test]
     fn test_cursor() {
-        Spi::connect(|client| {
+        Spi::connect(|mut client| {
             client.update("CREATE TABLE tests.cursor_table (id int)", None, None);
             client.update(
                 "INSERT INTO tests.cursor_table (id) \
@@ -224,7 +224,7 @@ mod tests {
 
     #[pg_test]
     fn test_cursor_prepared_statement() -> Result<(), pgx::spi::Error> {
-        Spi::connect(|client| {
+        Spi::connect(|mut client| {
             client.update("CREATE TABLE tests.cursor_table (id int)", None, None);
             client.update(
                 "INSERT INTO tests.cursor_table (id) \
@@ -248,7 +248,7 @@ mod tests {
 
     #[pg_test]
     fn test_cursor_by_name() -> Result<(), pgx::spi::Error> {
-        let cursor_name = Spi::connect(|client| {
+        let cursor_name = Spi::connect(|mut client| {
             client.update("CREATE TABLE tests.cursor_table (id int)", None, None);
             client.update(
                 "INSERT INTO tests.cursor_table (id) \
@@ -308,7 +308,7 @@ mod tests {
             assert_eq!(res.column_name(2).unwrap(), "b");
         });
 
-        Spi::connect(|client| {
+        Spi::connect(|mut client| {
             let res = client.update("SET TIME ZONE 'PST8PDT'", None, None);
 
             assert_eq!(0, res.columns());
@@ -324,7 +324,7 @@ mod tests {
     #[pg_test]
     fn test_spi_non_mut() -> Result<(), pgx::spi::Error> {
         // Ensures update and cursor APIs do not need mutable reference to SpiClient
-        Spi::connect(|client| {
+        Spi::connect(|mut client| {
             client.update("SELECT 1", None, None);
             let cursor = client.open_cursor("SELECT 1", None)?.detach_into_name();
             client.find_cursor(&cursor).map(|_| ())
@@ -413,4 +413,20 @@ mod tests {
     fn test_option() {
         assert!(Spi::get_one::<i32>("SELECT NULL::integer").unwrap().is_none());
     }
+
+    #[pg_test(error = "CREATE TABLE is not allowed in a non-volatile function")]
+    fn test_readwrite_in_readonly() {
+        // This is supposed to run in read-only
+        Spi::connect(|client| client.select("CREATE TABLE a ()", None, None));
+    }
+
+    #[pg_test]
+    fn test_readwrite_in_select_readwrite() {
+        Spi::connect(|mut client| {
+            // This is supposed to switch connection to read-write and run it there
+            client.update("CREATE TABLE a (id INT)", None, None);
+            // This is supposed to run in read-write
+            client.select("INSERT INTO a VALUES (1)", None, None);
+        });
+    }
 }

pgx-tests/src/tests/srf_tests.rs

@@ -177,7 +177,7 @@ mod tests {
 
     #[pg_test]
     fn test_srf_setof_datum_detoasting_with_borrow() {
-        let cnt = Spi::connect(|client| {
+        let cnt = Spi::connect(|mut client| {
             // build up a table with one large column that Postgres will be forced to TOAST
             client.update("CREATE TABLE test_srf_datum_detoasting AS SELECT array_to_string(array_agg(g),' ') s FROM (SELECT 'a' g FROM generate_series(1, 1000000)) x;", None, None);
 
@@ -195,7 +195,7 @@ mod tests {
 
     #[pg_test]
     fn test_srf_table_datum_detoasting_with_borrow() {
-        let cnt = Spi::connect(|client| {
+        let cnt = Spi::connect(|mut client| {
             // build up a table with one large column that Postgres will be forced to TOAST
             client.update("CREATE TABLE test_srf_datum_detoasting AS SELECT array_to_string(array_agg(g),' ') s FROM (SELECT 'a' g FROM generate_series(1, 1000000)) x;", None, None);
 

pgx-tests/src/tests/struct_type_tests.rs

@@ -124,7 +124,7 @@ mod tests {
 
     #[pg_test]
     fn test_complex_storage_and_retrieval() -> Result<(), pgx::spi::Error> {
-        let complex = Spi::connect(|client| {
+        let complex = Spi::connect(|mut client| {
             client.update(
                 "CREATE TABLE complex_test AS SELECT s as id, (s || '.0, 2.0' || s)::complex as value FROM generate_series(1, 1000) s;\
                 SELECT value FROM complex_test ORDER BY id;", None, None).first().get_one::<PgBox<Complex>>()