Merge pull request #2278 from wiredtiger/SERVER-21027-fix

SERVER-21027 Don't leave empty internal pages in the tree

(cherry picked from commit ba931c1)

4 files changed, 15 insertions, 20 deletions

diff --git a/src/btree/bt_split.c b/src/btree/bt_split.c
index 82a4dac226f..d2861e5237e 100644
--- a/src/btree/bt_split.c
+++ b/src/btree/bt_split.c
@@ -960,17 +960,11 @@ __split_parent(WT_SESSION_IMPL *session, WT_REF *ref,
 	result_entries = (parent_entries + new_entries) - deleted_entries;
 
 	/*
-	 * If the entire (sub)tree is empty, leave the first ref in place,
-	 * deleted.
+	 * If the entire (sub)tree is empty, give up: we can't leave an empty
+	 * internal page.
 	 */
-	if (result_entries == 0) {
-		next_ref = pindex->index[0];
-		WT_ASSERT(session, next_ref->state == WT_REF_SPLIT ||
-		    (next_ref == ref && ref->state == WT_REF_LOCKED));
-		next_ref->state = WT_REF_DELETED;
-		--deleted_entries;
-		result_entries = 1;
-	}
+	if (result_entries == 0)
+		return (0);
 
 	/*
 	 * Allocate and initialize a new page index array for the parent, then
@@ -1016,6 +1010,9 @@ __split_parent(WT_SESSION_IMPL *session, WT_REF *ref,
 			*alloc_refp++ = next_ref;
 	}
 
+	/* Check that we filled in all the entries. */
+	WT_ASSERT(session, alloc_refp - alloc_index->index == result_entries);
+
 	/*
 	 * Update the parent page's index: this update makes the split visible
 	 * to threads descending the tree.
diff --git a/src/evict/evict_file.c b/src/evict/evict_file.c
index 4cf3840ba8e..ed0ffb5b262 100644
--- a/src/evict/evict_file.c
+++ b/src/evict/evict_file.c
@@ -18,11 +18,8 @@ __wt_evict_file(WT_SESSION_IMPL *session, int syncop)
 	WT_DECL_RET;
 	WT_PAGE *page;
 	WT_REF *next_ref, *ref;
-	WT_TXN *txn;
 	bool evict_reset;
 
-	txn = &session->txn;
-
 	/*
 	 * We need exclusive access to the file -- disable ordinary eviction
 	 * and drain any blocks already queued.
@@ -32,9 +29,6 @@ __wt_evict_file(WT_SESSION_IMPL *session, int syncop)
 	/* Make sure the oldest transaction ID is up-to-date. */
 	__wt_txn_update_oldest(session, true);
 
-	if (txn->isolation == WT_ISO_READ_COMMITTED)
-		__wt_txn_get_snapshot(session);
-
 	/* Walk the tree, discarding pages. */
 	next_ref = NULL;
 	WT_ERR(__wt_tree_walk(session, &next_ref, NULL,
@@ -65,10 +59,6 @@ __wt_evict_file(WT_SESSION_IMPL *session, int syncop)
 		if (syncop == WT_SYNC_CLOSE && __wt_page_is_modified(page))
 			WT_ERR(__wt_reconcile(session, ref, NULL, WT_EVICTING));
 
-		/* Update our snapshot for each new page. */
-		if (txn->isolation == WT_ISO_READ_COMMITTED)
-			__wt_txn_get_snapshot(session);
-
 		/*
 		 * We can't evict the page just returned to us (it marks our
 		 * place in the tree), so move the walk to one page ahead of
diff --git a/src/include/txn.i b/src/include/txn.i
index 3152ff6bdd5..73d7f1f0518 100644
--- a/src/include/txn.i
+++ b/src/include/txn.i
@@ -187,6 +187,13 @@ __wt_txn_visible(WT_SESSION_IMPL *session, uint64_t id)
 	    session->dhandle == session->meta_dhandle)
 		return (true);
 
+	/*
+	 * If we don't have a transactional snapshot, only make stable updates
+	 * visible.
+	 */
+	if (!F_ISSET(txn, WT_TXN_HAS_SNAPSHOT))
+		return (__wt_txn_visible_all(session, id));
+
 	/* Transactions see their own changes. */
 	if (id == txn->id)
 		return (true);
diff --git a/src/reconcile/rec_write.c b/src/reconcile/rec_write.c
index 988b7e0a84f..73b7f4968e9 100644
--- a/src/reconcile/rec_write.c
+++ b/src/reconcile/rec_write.c
@@ -653,6 +653,7 @@ __rec_write_init(WT_SESSION_IMPL *session,
 	r->flags = flags;
 
 	/* Track if the page can be marked clean. */
+	r->max_txn = WT_TXN_NONE;
 	r->leave_dirty = false;
 
 	/* Raw compression. */