diff --git a/mdbx.h b/mdbx.h
index c800e641..2533e5c0 100644
--- a/mdbx.h
+++ b/mdbx.h
@@ -1648,10 +1648,22 @@ typedef void MDBX_debug_func(int type, const char *function, int line,
 
 LIBMDBX_API int mdbx_setup_debug(int flags, MDBX_debug_func *logger);
 
-typedef int MDBX_pgvisitor_func(uint64_t pgno, unsigned pgnumber, void *ctx,
-                                const char *dbi, const char *type,
-                                size_t nentries, size_t payload_bytes,
-                                size_t header_bytes, size_t unused_bytes);
+typedef enum {
+  MDBX_page_void,
+  MDBX_page_meta,
+  MDBX_page_large,
+  MDBX_page_branch,
+  MDBX_page_leaf,
+  MDBX_page_dupfixed_leaf,
+  MDBX_subpage_leaf,
+  MDBX_subpage_dupfixed_leaf
+} MDBX_page_type_t;
+
+typedef int MDBX_pgvisitor_func(uint64_t pgno, unsigned number, void *ctx,
+                                const char *dbi, size_t page_size,
+                                MDBX_page_type_t type, size_t nentries,
+                                size_t payload_bytes, size_t header_bytes,
+                                size_t unused_bytes);
 LIBMDBX_API int mdbx_env_pgwalk(MDBX_txn *txn, MDBX_pgvisitor_func *visitor,
                                 void *ctx);
 
diff --git a/src/mdbx.c b/src/mdbx.c
index 5064ee04..318d9667 100644
--- a/src/mdbx.c
+++ b/src/mdbx.c
@@ -1290,13 +1290,13 @@ static void mdbx_page_list(MDBX_page *mp) {
     type = "Leaf page";
     break;
   case P_LEAF | P_SUBP:
-    type = "Sub-page";
+    type = "Leaf sub-page";
     break;
   case P_LEAF | P_LEAF2:
-    type = "LEAF2 page";
+    type = "Leaf2 page";
     break;
   case P_LEAF | P_LEAF2 | P_SUBP:
-    type = "LEAF2 sub-page";
+    type = "Leaf2 sub-page";
     break;
   case P_OVERFLOW:
     mdbx_print("Overflow page %" PRIu64 " pages %u%s\n", pgno, mp->mp_pages,
@@ -11855,13 +11855,8 @@ typedef struct mdbx_walk_ctx {
 
 /* Depth-first tree traversal. */
 static int __cold mdbx_env_walk(mdbx_walk_ctx_t *ctx, const char *dbi,
-                                pgno_t pg, int deep) {
-  MDBX_page *mp;
-  int rc, i, nkeys;
-  size_t header_size, unused_size, payload_size, align_bytes;
-  const char *type;
-
-  if (pg == P_INVALID)
+                                pgno_t pgno, int deep) {
+  if (pgno == P_INVALID)
     return MDBX_SUCCESS; /* empty db */
 
   MDBX_cursor mc;
@@ -11869,116 +11864,174 @@ static int __cold mdbx_env_walk(mdbx_walk_ctx_t *ctx, const char *dbi,
   mc.mc_snum = 1;
   mc.mc_txn = ctx->mw_txn;
 
-  rc = mdbx_page_get(&mc, pg, &mp, NULL);
+  MDBX_page *mp;
+  int rc = mdbx_page_get(&mc, pgno, &mp, NULL);
   if (rc)
     return rc;
-  if (pg != mp->mp_pgno)
+  if (pgno != mp->mp_pgno)
     return MDBX_CORRUPTED;
 
-  nkeys = NUMKEYS(mp);
-  header_size = IS_LEAF2(mp) ? PAGEHDRSZ : PAGEHDRSZ + mp->mp_lower;
-  unused_size = SIZELEFT(mp);
-  payload_size = 0;
+  const int nkeys = NUMKEYS(mp);
+  size_t header_size = IS_LEAF2(mp) ? PAGEHDRSZ : PAGEHDRSZ + mp->mp_lower;
+  size_t unused_size = SIZELEFT(mp);
+  size_t payload_size = 0;
+  size_t align_bytes = 0;
+  MDBX_page_type_t type;
 
   /* LY: Don't use mask here, e.g bitwise
    * (P_BRANCH|P_LEAF|P_LEAF2|P_META|P_OVERFLOW|P_SUBP).
    * Pages should not me marked dirty/loose or otherwise. */
   switch (mp->mp_flags) {
   case P_BRANCH:
-    type = "branch";
-    if (nkeys < 1)
+    type = MDBX_page_branch;
+    if (nkeys < 2)
       return MDBX_CORRUPTED;
     break;
   case P_LEAF:
-    type = "leaf";
-    break;
-  case P_LEAF | P_SUBP:
-    type = "dupsort-subleaf";
+    type = MDBX_page_leaf;
     break;
   case P_LEAF | P_LEAF2:
-    type = "dupfixed-leaf";
+    type = MDBX_page_dupfixed_leaf;
     break;
-  case P_LEAF | P_LEAF2 | P_SUBP:
-    type = "dupsort-dupfixed-subleaf";
-    break;
-  case P_META:
-  case P_OVERFLOW:
-    __fallthrough;
   default:
     return MDBX_CORRUPTED;
   }
 
-  for (align_bytes = i = 0; i < nkeys;
+  for (int i = 0; i < nkeys;
        align_bytes += ((payload_size + align_bytes) & 1), i++) {
-    MDBX_node *node;
-
-    if (IS_LEAF2(mp)) {
+    if (type == MDBX_page_dupfixed_leaf) {
       /* LEAF2 pages have no mp_ptrs[] or node headers */
       payload_size += mp->mp_leaf2_ksize;
       continue;
     }
 
-    node = NODEPTR(mp, i);
-    payload_size += NODESIZE + node->mn_ksize;
+    MDBX_node *node = NODEPTR(mp, i);
+    payload_size += NODESIZE + NODEKSZ(node);
 
-    if (IS_BRANCH(mp)) {
+    if (type == MDBX_page_branch) {
       rc = mdbx_env_walk(ctx, dbi, NODEPGNO(node), deep);
       if (rc)
         return rc;
       continue;
     }
 
-    assert(IS_LEAF(mp));
-    if (node->mn_flags & F_BIGDATA) {
-      MDBX_page *omp;
-      pgno_t *opg;
-      size_t over_header, over_payload, over_unused;
+    assert(type == MDBX_page_leaf);
+    switch (node->mn_flags) {
+    case 0 /* usual node */: {
+      payload_size += NODEDSZ(node);
+    } break;
 
+    case F_BIGDATA /* long data on the large/overflow page */: {
       payload_size += sizeof(pgno_t);
-      opg = NODEDATA(node);
-      rc = mdbx_page_get(&mc, *opg, &omp, NULL);
+
+      MDBX_page *op;
+      pgno_t large_pgno;
+      memcpy(&large_pgno, NODEDATA(node), sizeof(pgno_t));
+      rc = mdbx_page_get(&mc, large_pgno, &op, NULL);
       if (rc)
         return rc;
-      if (*opg != omp->mp_pgno)
+
+      if (large_pgno != op->mp_pgno)
         return MDBX_CORRUPTED;
+
       /* LY: Don't use mask here, e.g bitwise
        * (P_BRANCH|P_LEAF|P_LEAF2|P_META|P_OVERFLOW|P_SUBP).
        * Pages should not me marked dirty/loose or otherwise. */
-      if (P_OVERFLOW != omp->mp_flags)
+      if (P_OVERFLOW != op->mp_flags)
         return MDBX_CORRUPTED;
 
-      over_header = PAGEHDRSZ;
-      over_payload = NODEDSZ(node);
-      over_unused = pgno2bytes(ctx->mw_txn->mt_env, omp->mp_pages) -
-                    over_payload - over_header;
+      const size_t over_header = PAGEHDRSZ;
+      const size_t over_payload = NODEDSZ(node);
+      const size_t over_unused = pgno2bytes(ctx->mw_txn->mt_env, op->mp_pages) -
+                                 over_payload - over_header;
 
-      rc = ctx->mw_visitor(*opg, omp->mp_pages, ctx->mw_user, dbi,
-                           "overflow-data", 1, over_payload, over_header,
+      rc = ctx->mw_visitor(large_pgno, op->mp_pages, ctx->mw_user, dbi,
+                           pgno2bytes(ctx->mw_txn->mt_env, op->mp_pages),
+                           MDBX_page_large, 1, over_payload, over_header,
                            over_unused);
-      if (rc)
-        return rc;
-      continue;
-    }
+    } break;
 
-    payload_size += NODEDSZ(node);
-    if (node->mn_flags & F_SUBDATA) {
-      MDBX_db *db = NODEDATA(node);
-      char *name = NULL;
+    case F_SUBDATA /* sub-db */: {
+      const size_t namelen = NODEKSZ(node);
+      if (namelen == 0 || NODEDSZ(node) != sizeof(MDBX_db))
+        return MDBX_CORRUPTED;
+      payload_size += sizeof(MDBX_db);
 
-      if (!(node->mn_flags & F_DUPDATA)) {
-        name = NODEKEY(node);
-        ptrdiff_t namelen = (char *)db - name;
-        name = memcpy(alloca(namelen + 1), name, namelen);
-        name[namelen] = 0;
+      MDBX_db db;
+      memcpy(&db, NODEDATA(node), sizeof(db));
+      char *name = memcpy(alloca(namelen + 1), NODEKEY(node), namelen);
+      name[namelen] = 0;
+      rc = mdbx_env_walk(ctx, name, db.md_root, deep + 1);
+    } break;
+
+    case F_SUBDATA | F_DUPDATA /* dupsorted sub-tree */: {
+      if (NODEDSZ(node) != sizeof(MDBX_db))
+        return MDBX_CORRUPTED;
+      payload_size += sizeof(MDBX_db);
+
+      MDBX_db db;
+      memcpy(&db, NODEDATA(node), sizeof(db));
+      rc = mdbx_env_walk(ctx, dbi, db.md_root, deep + 1);
+    } break;
+
+    case F_DUPDATA /* short sub-page */: {
+      if (NODEDSZ(node) < PAGEHDRSZ)
+        return MDBX_CORRUPTED;
+
+      MDBX_page *sp = NODEDATA(node);
+      const int nsubkeys = NUMKEYS(sp);
+      size_t subheader_size =
+          IS_LEAF2(sp) ? PAGEHDRSZ : PAGEHDRSZ + sp->mp_lower;
+      size_t subunused_size = SIZELEFT(sp);
+      size_t subpayload_size = 0;
+      size_t subalign_bytes = 0;
+      MDBX_page_type_t subtype;
+
+      switch (sp->mp_flags & ~P_DIRTY /* ignore for sub-pages */) {
+      case P_LEAF | P_SUBP:
+        subtype = MDBX_subpage_leaf;
+        break;
+      case P_LEAF | P_LEAF2 | P_SUBP:
+        subtype = MDBX_subpage_dupfixed_leaf;
+        break;
+      default:
+        return MDBX_CORRUPTED;
       }
-      rc = mdbx_env_walk(ctx, (name && name[0]) ? name : dbi, db->md_root,
-                         deep + 1);
-      if (rc)
-        return rc;
+
+      for (int j = 0; j < nsubkeys;
+           subalign_bytes += ((subpayload_size + subalign_bytes) & 1), j++) {
+
+        if (subtype == MDBX_subpage_dupfixed_leaf) {
+          /* LEAF2 pages have no mp_ptrs[] or node headers */
+          subpayload_size += sp->mp_leaf2_ksize;
+        } else {
+          assert(subtype == MDBX_subpage_leaf);
+          MDBX_node *subnode = NODEPTR(sp, j);
+          subpayload_size += NODESIZE + NODEKSZ(subnode) + NODEDSZ(subnode);
+          if (subnode->mn_flags != 0)
+            return MDBX_CORRUPTED;
+        }
+      }
+
+      rc = ctx->mw_visitor(pgno, 0, ctx->mw_user, dbi, NODEDSZ(node), subtype,
+                           nsubkeys, subpayload_size, subheader_size,
+                           subunused_size + subalign_bytes);
+      header_size += subheader_size;
+      unused_size += subunused_size;
+      payload_size += subpayload_size;
+      align_bytes += subalign_bytes;
+    } break;
+
+    default:
+      return MDBX_CORRUPTED;
     }
+
+    if (unlikely(rc))
+      return rc;
   }
 
-  return ctx->mw_visitor(mp->mp_pgno, 1, ctx->mw_user, dbi, type, nkeys,
+  return ctx->mw_visitor(mp->mp_pgno, 1, ctx->mw_user, dbi,
+                         ctx->mw_txn->mt_env->me_psize, type, nkeys,
                          payload_size, header_size, unused_size + align_bytes);
 }
 
@@ -11998,16 +12051,17 @@ int __cold mdbx_env_pgwalk(MDBX_txn *txn, MDBX_pgvisitor_func *visitor,
   ctx.mw_user = user;
   ctx.mw_visitor = visitor;
 
-  int rc = visitor(0, NUM_METAS, user, "meta", "meta", NUM_METAS,
-                   sizeof(MDBX_meta) * NUM_METAS, PAGEHDRSZ * NUM_METAS,
-                   (txn->mt_env->me_psize - sizeof(MDBX_meta) - PAGEHDRSZ) *
-                       NUM_METAS);
+  int rc = visitor(
+      0, NUM_METAS, user, "meta", pgno2bytes(txn->mt_env, NUM_METAS),
+      MDBX_page_meta, NUM_METAS, sizeof(MDBX_meta) * NUM_METAS,
+      PAGEHDRSZ * NUM_METAS,
+      (txn->mt_env->me_psize - sizeof(MDBX_meta) - PAGEHDRSZ) * NUM_METAS);
   if (!rc)
     rc = mdbx_env_walk(&ctx, "free", txn->mt_dbs[FREE_DBI].md_root, 0);
   if (!rc)
     rc = mdbx_env_walk(&ctx, "main", txn->mt_dbs[MAIN_DBI].md_root, 0);
   if (!rc)
-    rc = visitor(P_INVALID, 0, user, NULL, NULL, 0, 0, 0, 0);
+    rc = visitor(P_INVALID, 0, user, NULL, 0, MDBX_page_void, 0, 0, 0, 0);
   return rc;
 }
 
diff --git a/src/tools/mdbx_chk.c b/src/tools/mdbx_chk.c
index b4161746..d7e80c58 100644
--- a/src/tools/mdbx_chk.c
+++ b/src/tools/mdbx_chk.c
@@ -241,84 +241,112 @@ static uint64_t problems_pop(struct problem *list) {
 }
 
 static int pgvisitor(uint64_t pgno, unsigned pgnumber, void *ctx,
-                     const char *dbi_name, const char *type, size_t nentries,
+                     const char *dbi_name, size_t page_size,
+                     MDBX_page_type_t pagetype, size_t nentries,
                      size_t payload_bytes, size_t header_bytes,
                      size_t unused_bytes) {
   (void)ctx;
+  if (pagetype == MDBX_page_void)
+    return MDBX_SUCCESS;
 
-  if (type) {
-    uint64_t page_bytes = payload_bytes + header_bytes + unused_bytes;
-    size_t page_size = (size_t)pgnumber * envstat.ms_psize;
-    walk_dbi_t *dbi = pagemap_lookup_dbi(dbi_name);
-    if (!dbi)
-      return MDBX_ENOMEM;
+  uint64_t page_bytes = payload_bytes + header_bytes + unused_bytes;
+  walk_dbi_t *dbi = pagemap_lookup_dbi(dbi_name);
+  if (!dbi)
+    return MDBX_ENOMEM;
 
-    if (verbose > 2 && (!only_subdb || strcmp(only_subdb, dbi_name) == 0)) {
-      if (pgnumber == 1)
-        print("     %s-page %" PRIu64, type, pgno);
-      else
-        print("     %s-span %" PRIu64 "[%u]", type, pgno, pgnumber);
-      print(" of %s: header %" PRIiPTR ", payload %" PRIiPTR
-            ", unused %" PRIiPTR "\n",
-            dbi_name, header_bytes, payload_bytes, unused_bytes);
-    }
+  walk.pgcount += pgnumber;
+  const char *pagetype_caption;
+  switch (pagetype) {
+  default:
+    problem_add("page", pgno, "unknown page-type", "%u", (unsigned)pagetype);
+    pagetype_caption = "unknown";
+    break;
+  case MDBX_page_meta:
+    pagetype_caption = "meta";
+    break;
+  case MDBX_page_large:
+    pagetype_caption = "large";
+    break;
+  case MDBX_page_branch:
+    pagetype_caption = "branch";
+    break;
+  case MDBX_page_leaf:
+    pagetype_caption = "leaf";
+    break;
+  case MDBX_page_dupfixed_leaf:
+    pagetype_caption = "leaf-dupfixed";
+    break;
+  case MDBX_subpage_leaf:
+    pagetype_caption = "subleaf-dupsort";
+    break;
+  case MDBX_subpage_dupfixed_leaf:
+    pagetype_caption = "subleaf-dupfixed";
+    break;
+  }
 
-    walk.pgcount += pgnumber;
+  if (verbose > 2 && (!only_subdb || strcmp(only_subdb, dbi_name) == 0)) {
+    if (pgnumber == 1)
+      print("     %s-page %" PRIu64, pagetype_caption, pgno);
+    else
+      print("     %s-span %" PRIu64 "[%u]", pagetype_caption, pgno, pgnumber);
+    print(" of %s: header %" PRIiPTR ", payload %" PRIiPTR ", unused %" PRIiPTR
+          "\n",
+          dbi_name, header_bytes, payload_bytes, unused_bytes);
+  }
 
-    if (unused_bytes > page_size)
-      problem_add("page", pgno, "illegal unused-bytes",
-                  "%u < %" PRIuPTR " < %u", 0, unused_bytes, envstat.ms_psize);
+  if (unused_bytes > page_size)
+    problem_add("page", pgno, "illegal unused-bytes", "%u < %" PRIuPTR " < %u",
+                0, unused_bytes, envstat.ms_psize);
 
-    if (header_bytes < (int)sizeof(long) ||
-        (size_t)header_bytes >= envstat.ms_psize - sizeof(long))
-      problem_add("page", pgno, "illegal header-length",
-                  "%" PRIuPTR " < %" PRIuPTR " < %" PRIuPTR, sizeof(long),
-                  header_bytes, envstat.ms_psize - sizeof(long));
-    if (payload_bytes < 1) {
-      if (nentries > 1) {
-        problem_add("page", pgno, "zero size-of-entry",
-                    "payload %" PRIuPTR " bytes, %" PRIuPTR " entries",
-                    payload_bytes, nentries);
-        if ((size_t)header_bytes + unused_bytes < page_size) {
-          /* LY: hush a misuse error */
-          page_bytes = page_size;
-        }
-      } else {
-        problem_add("page", pgno, "empty",
-                    "payload %" PRIuPTR " bytes, %" PRIuPTR " entries",
-                    payload_bytes, nentries);
-        dbi->pages.empty += 1;
+  if (header_bytes < (int)sizeof(long) ||
+      (size_t)header_bytes >= envstat.ms_psize - sizeof(long))
+    problem_add("page", pgno, "illegal header-length",
+                "%" PRIuPTR " < %" PRIuPTR " < %" PRIuPTR, sizeof(long),
+                header_bytes, envstat.ms_psize - sizeof(long));
+  if (payload_bytes < 1) {
+    if (nentries > 1) {
+      problem_add("page", pgno, "zero size-of-entry",
+                  "payload %" PRIuPTR " bytes, %" PRIuPTR " entries",
+                  payload_bytes, nentries);
+      if ((size_t)header_bytes + unused_bytes < page_size) {
+        /* LY: hush a misuse error */
+        page_bytes = page_size;
       }
-    }
-
-    if (page_bytes != page_size) {
-      problem_add("page", pgno, "misused",
-                  "%" PRIu64 " != %" PRIu64 " (%" PRIuPTR "h + %" PRIuPTR
-                  "p + %" PRIuPTR "u)",
-                  page_size, page_bytes, header_bytes, payload_bytes,
-                  unused_bytes);
-      if (page_size > page_bytes)
-        dbi->lost_bytes += page_size - page_bytes;
     } else {
-      dbi->payload_bytes += payload_bytes + header_bytes;
-      walk.total_payload_bytes += payload_bytes + header_bytes;
+      problem_add("page", pgno, "empty",
+                  "payload %" PRIuPTR " bytes, %" PRIuPTR " entries",
+                  payload_bytes, nentries);
+      dbi->pages.empty += 1;
     }
+  }
 
-    if (pgnumber) {
-      do {
-        if (pgno >= lastpgno)
-          problem_add("page", pgno, "wrong page-no", "%" PRIu64 " > %" PRIu64,
-                      pgno, lastpgno);
-        else if (walk.pagemap[pgno])
-          problem_add("page", pgno, "already used", "in %s",
-                      walk.dbi[walk.pagemap[pgno]].name);
-        else {
-          walk.pagemap[pgno] = (short)(dbi - walk.dbi);
-          dbi->pages.total += 1;
-        }
-        ++pgno;
-      } while (--pgnumber);
-    }
+  if (page_bytes != page_size) {
+    problem_add("page", pgno, "misused",
+                "%" PRIu64 " != %" PRIu64 " (%" PRIuPTR "h + %" PRIuPTR
+                "p + %" PRIuPTR "u)",
+                page_size, page_bytes, header_bytes, payload_bytes,
+                unused_bytes);
+    if (page_size > page_bytes)
+      dbi->lost_bytes += page_size - page_bytes;
+  } else {
+    dbi->payload_bytes += payload_bytes + header_bytes;
+    walk.total_payload_bytes += payload_bytes + header_bytes;
+  }
+
+  if (pgnumber) {
+    do {
+      if (pgno >= lastpgno)
+        problem_add("page", pgno, "wrong page-no", "%" PRIu64 " > %" PRIu64,
+                    pgno, lastpgno);
+      else if (walk.pagemap[pgno])
+        problem_add("page", pgno, "already used", "in %s",
+                    walk.dbi[walk.pagemap[pgno]].name);
+      else {
+        walk.pagemap[pgno] = (short)(dbi - walk.dbi);
+        dbi->pages.total += 1;
+      }
+      ++pgno;
+    } while (--pgnumber);
   }
 
   return user_break ? MDBX_EINTR : MDBX_SUCCESS;