ITS#8258 fix rebalance/split

The tree height can also increase during rebalance, not just shrink.
This can happen if update_key needs to split a parent branch page.

diff --git a/libraries/liblmdb/mdb.c b/libraries/liblmdb/mdb.c
index 85952a1..028f646 100644 (file)
--- a/libraries/liblmdb/mdb.c
+++ b/libraries/liblmdb/mdb.c
@@ -7845,9 +7845,9 @@ mdb_page_merge(MDB_cursor *csrc, MDB_cursor *cdst)
                uint16_t depth = cdst->mc_db->md_depth;
                mdb_cursor_pop(cdst);
                rc = mdb_rebalance(cdst);
-               /* Did the tree shrink? */
-               if (depth > cdst->mc_db->md_depth)
-                       snum--;
+               /* Did the tree height change? */
+               if (depth != cdst->mc_db->md_depth)
+                       snum += cdst->mc_db->md_depth - depth;
                cdst->mc_snum = snum;
                cdst->mc_top = snum-1;
        }
@@ -8039,7 +8039,7 @@ mdb_rebalance(MDB_cursor *mc)
         */
        if (PAGEFILL(mc->mc_txn->mt_env, mn.mc_pg[mn.mc_top]) >= thresh && NUMKEYS(mn.mc_pg[mn.mc_top]) > minkeys) {
                rc = mdb_node_move(&mn, mc);
-               if (mc->mc_ki[ptop]) {
+               if (mc->mc_ki[mc->mc_top-1]) {
                        oldki++;
                }
        } else {
@@ -8253,8 +8253,7 @@ mdb_page_split(MDB_cursor *mc, MDB_val *newkey, MDB_val *newdata, pgno_t newpgno
                mc->mc_ki[0] = 0;
                mc->mc_db->md_root = pp->mp_pgno;
                DPRINTF(("root split! new root = %"Z"u", pp->mp_pgno));
-               mc->mc_db->md_depth++;
-               new_root = 1;
+               new_root = mc->mc_db->md_depth++;
 
                /* Add left (implicit) pointer. */
                if ((rc = mdb_node_add(mc, 0, NULL, NULL, mp->mp_pgno, 0)) != MDB_SUCCESS) {
@@ -8567,7 +8566,7 @@ mdb_page_split(MDB_cursor *mc, MDB_val *newkey, MDB_val *newdata, pgno_t newpgno
                        if (new_root) {
                                int k;
                                /* root split */
-                               for (k=m3->mc_top; k>=0; k--) {
+                               for (k=new_root; k>=0; k--) {
                                        m3->mc_ki[k+1] = m3->mc_ki[k];
                                        m3->mc_pg[k+1] = m3->mc_pg[k];
                                }