Update comments on nbtree stack struct.

Adjust the struct comment that describes how page splits use their
descent stack to cascade up the tree from the leaf level.

In passing, fix up some unrelated nbtree comments that had typos or were
obsolete.

1 files changed, 5 insertions, 2 deletions

diff --git a/src/include/access/nbtree.h b/src/include/access/nbtree.h
index 7e54c456f7d..52eafe6b000 100644
--- a/src/include/access/nbtree.h
+++ b/src/include/access/nbtree.h
@@ -406,8 +406,11 @@ typedef struct BTMetaPageData
  * BTStackData -- As we descend a tree, we push the location of pivot
  * tuples whose downlink we are about to follow onto a private stack.  If
  * we split a leaf, we use this stack to walk back up the tree and insert
- * data into its parent page at the correct location.  We may also have to
- * recursively split a grandparent of the leaf page (and so on).
+ * data into its parent page at the correct location.  We also have to
+ * recursively insert into the grandparent page if and when the parent page
+ * splits.  Our private stack can become stale due to concurrent page
+ * splits and page deletions, but it should never give us an irredeemably
+ * bad picture.
  */
 typedef struct BTStackData
 {