MDEV-12779 Oracle/DB2 Compatibility Implicit Ordering for ROW_NUMBER OVER

Users expect window functions to produce a certain ordering of rows in
the final result set. Although the standard does not require this, we
already have the filesort result done for when we computed the window
function. If there is no ORDER BY attached to the query, just keep it
till the SELECT is completely evaluated and use that to print the
result.

Update test cases as many did not take care to guarantee a stable
result.

1 files changed, 9 insertions, 0 deletions

diff --git a/mysys/mf_iocache.c b/mysys/mf_iocache.c
index aea41886f05..673f9762a86 100644
--- a/mysys/mf_iocache.c
+++ b/mysys/mf_iocache.c
@@ -353,6 +353,15 @@ int init_slave_io_cache(IO_CACHE *master, IO_CACHE *slave)
 
 void end_slave_io_cache(IO_CACHE *cache)
 {
+  /* Remove the cache from the next_file_user circular linked list. */
+  if (cache->next_file_user != cache)
+  {
+    IO_CACHE *p= cache->next_file_user;
+    while (p->next_file_user != cache)
+      p= p->next_file_user;
+    p->next_file_user= cache->next_file_user;
+
+  }
   my_free(cache->buffer);
 }