If the application does a checkpoint (regardless whether it's named or

internal), a checkpoint by the name must exist.  This is complicated by
the fact that this applies to empty row-store files as well which we
go to some effort to avoid writing.  Ref #301.

Re-work the checkpoint code to skip unmodified objects when closing a
file (whatever checkpoints we have at that point are sufficient), and
to skip unmodified objects when the checkpoint we're taking is named
the same as the last checkpoint we have and we're not deleting other
checkpoints (which might free up space).

Remove the recent change that made the __wt_page_modify_set function
also mark the tree dirty: this is incorrect because the "dirty page"
flag climbs the tree during reconciliation: that doesn't mean the tree
is no longer "clean", the process of checkpointing is what cleans the
tree.

Change the btree handle create functions, and the btree salvage
functions, to set the tree and page dirty flags when instantiating new
pages (it doesn't matter whether we do or not, because currently the
tree flag only matters to the checkpoint function, but it's no longer a
problem either, and it's consistent with the way we handle other "dirty"
operations).

1 files changed, 42 insertions, 0 deletions

diff --git a/test/suite/test_checkpoint01.py b/test/suite/test_checkpoint01.py
index 4596ae8e971..a279ce937d9 100644
--- a/test/suite/test_checkpoint01.py
+++ b/test/suite/test_checkpoint01.py
@@ -328,6 +328,48 @@ class test_checkpoint_last_name(wttest.WiredTigerTestCase):
                 self.assertRaisesWithMessage(wiredtiger.WiredTigerError,
                     lambda: self.session.checkpoint(conf), msg)
 
+class test_checkpoint_empty(wttest.WiredTigerTestCase):
+    scenarios = [
+        ('file', dict(uri='file:checkpoint')),
+        ('table', dict(uri='table:checkpoint')),
+    ]
+
+    # Create an empty file, do one of 4 cases of checkpoint, then verify the
+    # checkpoints exist.   The reason for the 4 cases is we must create all
+    # checkpoints an application can explicitly reference using a cursor, and
+    # I want to test when other types of checkpoints are created before the
+    # checkpoint we really need.
+    # Case 1: a named checkpoint
+    def test_checkpoint_empty_one(self):
+        self.session.create(self.uri, "key_format=S,value_format=S")
+        self.session.checkpoint('name=ckpt')
+        cursor = self.session.open_cursor(self.uri, None, "checkpoint=ckpt")
+
+    # Case 2: an internal checkpoint
+    def test_checkpoint_empty_two(self):
+        self.session.create(self.uri, "key_format=S,value_format=S")
+        self.session.checkpoint()
+        cursor = self.session.open_cursor(
+            self.uri, None, "checkpoint=WiredTigerCheckpoint")
+
+    # Case 3: a named checkpoint, then an internal checkpoint
+    def test_checkpoint_empty_three(self):
+        self.session.create(self.uri, "key_format=S,value_format=S")
+        self.session.checkpoint('name=ckpt')
+        self.session.checkpoint()
+        cursor = self.session.open_cursor(self.uri, None, "checkpoint=ckpt")
+        cursor = self.session.open_cursor(
+            self.uri, None, "checkpoint=WiredTigerCheckpoint")
+
+    # Case 4: an internal checkpoint, then a named checkpoint
+    def test_checkpoint_empty_four(self):
+        self.session.create(self.uri, "key_format=S,value_format=S")
+        self.session.checkpoint()
+        self.session.checkpoint('name=ckpt')
+        cursor = self.session.open_cursor(self.uri, None, "checkpoint=ckpt")
+        cursor = self.session.open_cursor(
+            self.uri, None, "checkpoint=WiredTigerCheckpoint")
+
 
 if __name__ == '__main__':
     wttest.run()