diff --git a/src/elements/core.c b/src/elements/core.c
index 7d145ae8..8da58836 100644
--- a/src/elements/core.c
+++ b/src/elements/core.c
@@ -9449,152 +9449,15 @@ int mdbx_cursor_put(MDBX_cursor *mc, MDBX_val *key, MDBX_val *data,
     }
 
   more:;
-    MDBX_node *leaf = NODEPTR(mc->mc_pg[mc->mc_top], mc->mc_ki[mc->mc_top]);
-    olddata.iov_len = NODEDSZ(leaf);
-    olddata.iov_base = NODEDATA(leaf);
-
-    /* DB has dups? */
-    if (F_ISSET(mc->mc_db->md_flags, MDBX_DUPSORT)) {
-      /* Prepare (sub-)page/sub-DB to accept the new item, if needed.
-       * fp: old sub-page or a header faking it.
-       * mp: new (sub-)page.  offset: growth in page size.
-       * xdata: node data with new page or DB. */
-      unsigned i, offset = 0;
-      MDBX_page *mp = fp = xdata.iov_base = env->me_pbuf;
-      mp->mp_pgno = mc->mc_pg[mc->mc_top]->mp_pgno;
-
-      /* Was a single item before, must convert now */
-      if (!F_ISSET(leaf->mn_flags, F_DUPDATA)) {
-
-        /* does data match? */
-        if (!mc->mc_dbx->md_dcmp(data, &olddata)) {
-          if (unlikely(flags & (MDBX_NODUPDATA | MDBX_APPENDDUP)))
-            return MDBX_KEYEXIST;
-          /* overwrite it */
-          goto current;
-        }
-
-        /* Just overwrite the current item */
-        if (flags & MDBX_CURRENT)
-          goto current;
-
-        /* Back up original data item */
-        dupdata_flag = 1;
-        dkey.iov_len = olddata.iov_len;
-        dkey.iov_base = memcpy(fp + 1, olddata.iov_base, olddata.iov_len);
-
-        /* Make sub-page header for the dup items, with dummy body */
-        fp->mp_flags = P_LEAF | P_DIRTY | P_SUBP;
-        fp->mp_lower = 0;
-        xdata.iov_len = PAGEHDRSZ + dkey.iov_len + data->iov_len;
-        if (mc->mc_db->md_flags & MDBX_DUPFIXED) {
-          fp->mp_flags |= P_LEAF2;
-          fp->mp_leaf2_ksize = (uint16_t)data->iov_len;
-          xdata.iov_len += 2 * data->iov_len; /* leave space for 2 more */
-          mdbx_cassert(mc, xdata.iov_len <= env->me_psize);
-        } else {
-          xdata.iov_len += 2 * (sizeof(indx_t) + NODESIZE) +
-                           (dkey.iov_len & 1) + (data->iov_len & 1);
-          mdbx_cassert(mc, xdata.iov_len <= env->me_psize);
-        }
-        fp->mp_upper = (uint16_t)(xdata.iov_len - PAGEHDRSZ);
-        olddata.iov_len = xdata.iov_len; /* pretend olddata is fp */
-      } else if (leaf->mn_flags & F_SUBDATA) {
-        /* Data is on sub-DB, just store it */
-        flags |= F_DUPDATA | F_SUBDATA;
-        goto put_sub;
-      } else {
-        /* Data is on sub-page */
-        fp = olddata.iov_base;
-        switch (flags) {
-        default:
-          if (!(mc->mc_db->md_flags & MDBX_DUPFIXED)) {
-            offset = EVEN(NODESIZE + sizeof(indx_t) + data->iov_len);
-            break;
-          }
-          offset = fp->mp_leaf2_ksize;
-          if (SIZELEFT(fp) < offset) {
-            offset *= 4; /* space for 4 more */
-            break;
-          }
-          /* FALLTHRU: Big enough MDBX_DUPFIXED sub-page */
-          __fallthrough;
-        case MDBX_CURRENT | MDBX_NODUPDATA:
-        case MDBX_CURRENT:
-          fp->mp_flags |= P_DIRTY;
-          fp->mp_pgno = mp->mp_pgno;
-          mc->mc_xcursor->mx_cursor.mc_pg[0] = fp;
-          flags |= F_DUPDATA;
-          goto put_sub;
-        }
-        xdata.iov_len = olddata.iov_len + offset;
-      }
-
-      fp_flags = fp->mp_flags;
-      if (NODESIZE + NODEKSZ(leaf) + xdata.iov_len > env->me_nodemax) {
-        /* Too big for a sub-page, convert to sub-DB */
-        fp_flags &= ~P_SUBP;
-      prep_subDB:
-        dummy.md_xsize = 0;
-        dummy.md_flags = 0;
-        if (mc->mc_db->md_flags & MDBX_DUPFIXED) {
-          fp_flags |= P_LEAF2;
-          dummy.md_xsize = fp->mp_leaf2_ksize;
-          dummy.md_flags = MDBX_DUPFIXED;
-          if (mc->mc_db->md_flags & MDBX_INTEGERDUP)
-            dummy.md_flags |= MDBX_INTEGERKEY;
-        }
-        dummy.md_depth = 1;
-        dummy.md_branch_pages = 0;
-        dummy.md_leaf_pages = 1;
-        dummy.md_overflow_pages = 0;
-        dummy.md_entries = NUMKEYS(fp);
-        xdata.iov_len = sizeof(MDBX_db);
-        xdata.iov_base = &dummy;
-        if ((rc = mdbx_page_alloc(mc, 1, &mp, MDBX_ALLOC_ALL)))
-          return rc;
-        mc->mc_db->md_leaf_pages += 1;
-        mdbx_cassert(mc, env->me_psize > olddata.iov_len);
-        offset = env->me_psize - (unsigned)olddata.iov_len;
-        flags |= F_DUPDATA | F_SUBDATA;
-        dummy.md_root = mp->mp_pgno;
-        dummy.md_seq = dummy.md_merkle = 0;
-        sub_root = mp;
-      }
-      if (mp != fp) {
-        mp->mp_flags = fp_flags | P_DIRTY;
-        mp->mp_leaf2_ksize = fp->mp_leaf2_ksize;
-        mp->mp_lower = fp->mp_lower;
-        mdbx_cassert(mc, fp->mp_upper + offset <= UINT16_MAX);
-        mp->mp_upper = (indx_t)(fp->mp_upper + offset);
-        if (unlikely(fp_flags & P_LEAF2)) {
-          memcpy(PAGEDATA(mp), PAGEDATA(fp), NUMKEYS(fp) * fp->mp_leaf2_ksize);
-        } else {
-          memcpy((char *)mp + mp->mp_upper + PAGEHDRSZ,
-                 (char *)fp + fp->mp_upper + PAGEHDRSZ,
-                 olddata.iov_len - fp->mp_upper - PAGEHDRSZ);
-          memcpy((char *)(&mp->mp_ptrs), (char *)(&fp->mp_ptrs),
-                 NUMKEYS(fp) * sizeof(mp->mp_ptrs[0]));
-          for (i = 0; i < NUMKEYS(fp); i++) {
-            mdbx_cassert(mc, mp->mp_ptrs[i] + offset <= UINT16_MAX);
-            mp->mp_ptrs[i] += (indx_t)offset;
-          }
-        }
-      }
-
-      rdata = &xdata;
-      flags |= F_DUPDATA;
-      do_sub = true;
-      if (!insert_key)
-        mdbx_node_del(mc, 0);
-      goto new_sub;
+    if (mdbx_audit_enabled()) {
+      int err = mdbx_cursor_check(mc, false);
+      if (unlikely(err != MDBX_SUCCESS))
+        return err;
     }
-  current:
-    /* MDBX passes F_SUBDATA in 'flags' to write a DB record */
-    if (unlikely((leaf->mn_flags ^ flags) & F_SUBDATA))
-      return MDBX_INCOMPATIBLE;
+    MDBX_node *leaf = NODEPTR(mc->mc_pg[mc->mc_top], mc->mc_ki[mc->mc_top]);
+
     /* overflow page overwrites need special handling */
-    if (F_ISSET(leaf->mn_flags, F_BIGDATA)) {
+    if (unlikely(F_ISSET(leaf->mn_flags, F_BIGDATA))) {
       MDBX_page *omp;
       pgno_t pg;
       int level, ovpages,
@@ -9602,7 +9465,7 @@ int mdbx_cursor_put(MDBX_cursor *mc, MDBX_val *key, MDBX_val *data,
                        ? OVPAGES(env, data->iov_len)
                        : 0;
 
-      memcpy(&pg, olddata.iov_base, sizeof(pg));
+      memcpy(&pg, NODEDATA(leaf), sizeof(pg));
       if (unlikely((rc2 = mdbx_page_get(mc, pg, &omp, &level)) != 0))
         return rc2;
       ovpages = omp->mp_pages;
@@ -9667,34 +9530,184 @@ int mdbx_cursor_put(MDBX_cursor *mc, MDBX_val *key, MDBX_val *data,
       }
       if ((rc2 = mdbx_ovpage_free(mc, omp)) != MDBX_SUCCESS)
         return rc2;
-    } else if (data->iov_len == olddata.iov_len) {
-      mdbx_cassert(mc, EVEN(key->iov_len) == EVEN(leaf->mn_ksize));
-      /* same size, just replace it. Note that we could
-       * also reuse this node if the new data is smaller,
-       * but instead we opt to shrink the node in that case. */
-      if (F_ISSET(flags, MDBX_RESERVE))
-        data->iov_base = olddata.iov_base;
-      else if (!(mc->mc_flags & C_SUB))
-        memcpy(olddata.iov_base, data->iov_base, data->iov_len);
-      else {
-        mdbx_cassert(mc, NUMKEYS(mc->mc_pg[mc->mc_top]) == 1);
-        mdbx_cassert(mc, PAGETYPE(mc->mc_pg[mc->mc_top]) == P_LEAF);
-        mdbx_cassert(mc, NODEDSZ(leaf) == 0);
-        mdbx_cassert(mc, leaf->mn_flags == 0);
-        mdbx_cassert(mc, key->iov_len < UINT16_MAX);
-        leaf->mn_ksize = (uint16_t)key->iov_len;
-        memcpy(NODEKEY(leaf), key->iov_base, key->iov_len);
-        mdbx_cassert(mc, (char *)NODEKEY(leaf) + NODEDSZ(leaf) <
-                             (char *)(mc->mc_pg[mc->mc_top]) + env->me_psize);
-        goto fix_parent;
+    } else {
+      olddata.iov_len = NODEDSZ(leaf);
+      olddata.iov_base = NODEDATA(leaf);
+      mdbx_cassert(mc, (char *)olddata.iov_base + olddata.iov_len <=
+                           (char *)(mc->mc_pg[mc->mc_top]) + env->me_psize);
+
+      /* DB has dups? */
+      if (F_ISSET(mc->mc_db->md_flags, MDBX_DUPSORT)) {
+        /* Prepare (sub-)page/sub-DB to accept the new item, if needed.
+         * fp: old sub-page or a header faking it.
+         * mp: new (sub-)page.  offset: growth in page size.
+         * xdata: node data with new page or DB. */
+        unsigned i, offset = 0;
+        MDBX_page *mp = fp = xdata.iov_base = env->me_pbuf;
+        mp->mp_pgno = mc->mc_pg[mc->mc_top]->mp_pgno;
+
+        /* Was a single item before, must convert now */
+        if (!F_ISSET(leaf->mn_flags, F_DUPDATA)) {
+
+          /* does data match? */
+          if (!mc->mc_dbx->md_dcmp(data, &olddata)) {
+            if (unlikely(flags & (MDBX_NODUPDATA | MDBX_APPENDDUP)))
+              return MDBX_KEYEXIST;
+            /* overwrite it */
+            goto current;
+          }
+
+          /* Just overwrite the current item */
+          if (flags & MDBX_CURRENT)
+            goto current;
+
+          /* Back up original data item */
+          dupdata_flag = 1;
+          dkey.iov_len = olddata.iov_len;
+          dkey.iov_base = memcpy(fp + 1, olddata.iov_base, olddata.iov_len);
+
+          /* Make sub-page header for the dup items, with dummy body */
+          fp->mp_flags = P_LEAF | P_DIRTY | P_SUBP;
+          fp->mp_lower = 0;
+          xdata.iov_len = PAGEHDRSZ + dkey.iov_len + data->iov_len;
+          if (mc->mc_db->md_flags & MDBX_DUPFIXED) {
+            fp->mp_flags |= P_LEAF2;
+            fp->mp_leaf2_ksize = (uint16_t)data->iov_len;
+            xdata.iov_len += 2 * data->iov_len; /* leave space for 2 more */
+            mdbx_cassert(mc, xdata.iov_len <= env->me_psize);
+          } else {
+            xdata.iov_len += 2 * (sizeof(indx_t) + NODESIZE) +
+                             (dkey.iov_len & 1) + (data->iov_len & 1);
+            mdbx_cassert(mc, xdata.iov_len <= env->me_psize);
+          }
+          fp->mp_upper = (uint16_t)(xdata.iov_len - PAGEHDRSZ);
+          olddata.iov_len = xdata.iov_len; /* pretend olddata is fp */
+        } else if (leaf->mn_flags & F_SUBDATA) {
+          /* Data is on sub-DB, just store it */
+          flags |= F_DUPDATA | F_SUBDATA;
+          goto put_sub;
+        } else {
+          /* Data is on sub-page */
+          fp = olddata.iov_base;
+          switch (flags) {
+          default:
+            if (!(mc->mc_db->md_flags & MDBX_DUPFIXED)) {
+              offset = EVEN(NODESIZE + sizeof(indx_t) + data->iov_len);
+              break;
+            }
+            offset = fp->mp_leaf2_ksize;
+            if (SIZELEFT(fp) < offset) {
+              offset *= 4; /* space for 4 more */
+              break;
+            }
+            /* FALLTHRU: Big enough MDBX_DUPFIXED sub-page */
+            __fallthrough;
+          case MDBX_CURRENT | MDBX_NODUPDATA:
+          case MDBX_CURRENT:
+            fp->mp_flags |= P_DIRTY;
+            fp->mp_pgno = mp->mp_pgno;
+            mc->mc_xcursor->mx_cursor.mc_pg[0] = fp;
+            flags |= F_DUPDATA;
+            goto put_sub;
+          }
+          xdata.iov_len = olddata.iov_len + offset;
+        }
+
+        fp_flags = fp->mp_flags;
+        if (NODESIZE + NODEKSZ(leaf) + xdata.iov_len > env->me_nodemax) {
+          /* Too big for a sub-page, convert to sub-DB */
+          fp_flags &= ~P_SUBP;
+        prep_subDB:
+          dummy.md_xsize = 0;
+          dummy.md_flags = 0;
+          if (mc->mc_db->md_flags & MDBX_DUPFIXED) {
+            fp_flags |= P_LEAF2;
+            dummy.md_xsize = fp->mp_leaf2_ksize;
+            dummy.md_flags = MDBX_DUPFIXED;
+            if (mc->mc_db->md_flags & MDBX_INTEGERDUP)
+              dummy.md_flags |= MDBX_INTEGERKEY;
+          }
+          dummy.md_depth = 1;
+          dummy.md_branch_pages = 0;
+          dummy.md_leaf_pages = 1;
+          dummy.md_overflow_pages = 0;
+          dummy.md_entries = NUMKEYS(fp);
+          xdata.iov_len = sizeof(MDBX_db);
+          xdata.iov_base = &dummy;
+          if ((rc = mdbx_page_alloc(mc, 1, &mp, MDBX_ALLOC_ALL)))
+            return rc;
+          mc->mc_db->md_leaf_pages += 1;
+          mdbx_cassert(mc, env->me_psize > olddata.iov_len);
+          offset = env->me_psize - (unsigned)olddata.iov_len;
+          flags |= F_DUPDATA | F_SUBDATA;
+          dummy.md_root = mp->mp_pgno;
+          dummy.md_seq = dummy.md_merkle = 0;
+          sub_root = mp;
+        }
+        if (mp != fp) {
+          mp->mp_flags = fp_flags | P_DIRTY;
+          mp->mp_leaf2_ksize = fp->mp_leaf2_ksize;
+          mp->mp_lower = fp->mp_lower;
+          mdbx_cassert(mc, fp->mp_upper + offset <= UINT16_MAX);
+          mp->mp_upper = (indx_t)(fp->mp_upper + offset);
+          if (unlikely(fp_flags & P_LEAF2)) {
+            memcpy(PAGEDATA(mp), PAGEDATA(fp),
+                   NUMKEYS(fp) * fp->mp_leaf2_ksize);
+          } else {
+            memcpy((char *)mp + mp->mp_upper + PAGEHDRSZ,
+                   (char *)fp + fp->mp_upper + PAGEHDRSZ,
+                   olddata.iov_len - fp->mp_upper - PAGEHDRSZ);
+            memcpy((char *)(&mp->mp_ptrs), (char *)(&fp->mp_ptrs),
+                   NUMKEYS(fp) * sizeof(mp->mp_ptrs[0]));
+            for (i = 0; i < NUMKEYS(fp); i++) {
+              mdbx_cassert(mc, mp->mp_ptrs[i] + offset <= UINT16_MAX);
+              mp->mp_ptrs[i] += (indx_t)offset;
+            }
+          }
+        }
+
+        rdata = &xdata;
+        flags |= F_DUPDATA;
+        do_sub = true;
+        if (!insert_key)
+          mdbx_node_del(mc, 0);
+        goto new_sub;
       }
 
-      if (mdbx_audit_enabled()) {
-        int err = mdbx_cursor_check(mc, false);
-        if (unlikely(err != MDBX_SUCCESS))
-          return err;
+      /* MDBX passes F_SUBDATA in 'flags' to write a DB record */
+      if (unlikely((leaf->mn_flags ^ flags) & F_SUBDATA))
+        return MDBX_INCOMPATIBLE;
+
+    current:
+      if (data->iov_len == olddata.iov_len) {
+        mdbx_cassert(mc, EVEN(key->iov_len) == EVEN(leaf->mn_ksize));
+        /* same size, just replace it. Note that we could
+         * also reuse this node if the new data is smaller,
+         * but instead we opt to shrink the node in that case. */
+        if (F_ISSET(flags, MDBX_RESERVE))
+          data->iov_base = olddata.iov_base;
+        else if (!(mc->mc_flags & C_SUB))
+          memcpy(olddata.iov_base, data->iov_base, data->iov_len);
+        else {
+          mdbx_cassert(mc, NUMKEYS(mc->mc_pg[mc->mc_top]) == 1);
+          mdbx_cassert(mc, PAGETYPE(mc->mc_pg[mc->mc_top]) == P_LEAF);
+          mdbx_cassert(mc, NODEDSZ(leaf) == 0);
+          mdbx_cassert(mc, leaf->mn_flags == 0);
+          mdbx_cassert(mc, key->iov_len < UINT16_MAX);
+          leaf->mn_ksize = (uint16_t)key->iov_len;
+          memcpy(NODEKEY(leaf), key->iov_base, key->iov_len);
+          mdbx_cassert(mc, (char *)NODEKEY(leaf) + NODEDSZ(leaf) <
+                               (char *)(mc->mc_pg[mc->mc_top]) + env->me_psize);
+          goto fix_parent;
+        }
+
+        if (mdbx_audit_enabled()) {
+          int err = mdbx_cursor_check(mc, false);
+          if (unlikely(err != MDBX_SUCCESS))
+            return err;
+        }
+        return MDBX_SUCCESS;
       }
-      return MDBX_SUCCESS;
     }
     mdbx_node_del(mc, 0);
   }