Hi, Thanks for the review.
> BEGIN ISOLATION LEVEL READ COMMITTED;
> DECLARE c CURSOR FOR SELECT 1;
> WAIT FOR LSN '0/0';
> -- ERROR: WAIT FOR must be called without an active or registered snapshot
>
> BEGIN ISOLATION LEVEL READ COMMITTED;
> SELECT pg_export_snapshot();
> WAIT FOR LSN '0/0';
> -- ERROR: WAIT FOR must be called without an active or registered snapshot
This means there is a bug in the ERROR message DETAIL. Thanks for pointing
this out.
```
postgres=# begin;
BEGIN
postgres=*# DECLARE c CURSOR FOR SELECT 1;
DECLARE CURSOR
postgres=*# WAIT FOR LSN '0/0' WITH (mode 'PRIMARY_FLUSH');
ERROR: WAIT FOR must be called without an active or registered snapshot
DETAIL: WAIT FOR cannot be executed within a transaction with an
isolation level higher than READ COMMITTED.
postgres=!#
```
So I fixed this by first checking the isolation level and using "WAIT
FOR cannot be executed ... READ COMMITTED"
as the errmsg. The existing snapshot check must come after that.
I also added tests to cover the three relevant cases: READ COMMITTED
with a snapshot, and
REPEATABLE READ both with and without a snapshot. The REPEATABLE
READ-with-snapshot
case was already covered, but its expected error message needed to be updated.
The results looks like this:
```
postgres=# BEGIN ISOLATION LEVEL REPEATABLE READ;
BEGIN
postgres=*# select 1;
?column?
----------
1
(1 row)
postgres=*# WAIT FOR LSN '0/0' WITH (mode 'PRIMARY_FLUSH');
ERROR: WAIT FOR cannot be executed within a transaction with an
isolation level higher than READ COMMITTED
postgres=!#
```
```
postgres=# BEGIN ISOLATION LEVEL REPEATABLE READ;
BEGIN
postgres=*# WAIT FOR LSN '0/0' WITH (mode 'PRIMARY_FLUSH');
ERROR: WAIT FOR cannot be executed within a transaction with an
isolation level higher than READ COMMITTED
postgres=!#
```
```
postgres=# BEGIN;
BEGIN
postgres=*# DECLARE c CURSOR FOR SELECT 1;
DECLARE CURSOR
postgres=*#
postgres=*# WAIT FOR LSN '0/0' WITH (mode 'PRIMARY_FLUSH');
ERROR: WAIT FOR must be called without an active or registered snapshot
postgres=!#
```
--
Sami
v2-0001-Fix-WAIT-FOR-rejection-errors.patch
Description: Binary data
