mdbx: добавление гистограммы количества multi-значений/дубликатов в chk.

Author: erthink

mdbx.h

@@ -6541,6 +6541,8 @@ typedef struct MDBX_chk_table {
     struct MDBX_chk_histogram key_len;
     /// Values length histogram
     struct MDBX_chk_histogram val_len;
+    /// Number of multi-values (aka duplicates) histogram
+    struct MDBX_chk_histogram multival;
   } histogram;
 } MDBX_chk_table_t;
 

src/chk.c

@@ -1139,6 +1139,7 @@ __cold static int chk_db(MDBX_chk_scope_t *const scope, MDBX_dbi dbi, MDBX_chk_t
   const size_t maxkeysize = mdbx_env_get_maxkeysize_ex(env, tbl->flags);
   MDBX_val prev_key = {nullptr, 0}, prev_data = {nullptr, 0};
   MDBX_val key, data;
+  size_t dups_count = 0;
   err = mdbx_cursor_get(cursor, &key, &data, MDBX_FIRST);
   while (err == MDBX_SUCCESS) {
     err = chk_check_break(scope);
@@ -1162,6 +1163,12 @@ __cold static int chk_db(MDBX_chk_scope_t *const scope, MDBX_dbi dbi, MDBX_chk_t
     }
 
     if (prev_key.iov_base) {
+      if (key.iov_base == prev_key.iov_base)
+        dups_count += 1;
+      else {
+        histogram_acc(dups_count, &tbl->histogram.multival);
+        dups_count = 0;
+      }
       if (prev_data.iov_base && !bad_data && (tbl->flags & MDBX_DUPFIXED) && prev_data.iov_len != data.iov_len) {
         chk_object_issue(scope, "entry", record_count, "different data length", "%" PRIuPTR " != %" PRIuPTR,
                          prev_data.iov_len, data.iov_len);
@@ -1248,17 +1255,27 @@ __cold static int chk_db(MDBX_chk_scope_t *const scope, MDBX_dbi dbi, MDBX_chk_t
     err = mdbx_cursor_get(cursor, &key, &data, MDBX_NEXT);
   }
 
+  if (prev_key.iov_base)
+    histogram_acc(dups_count, &tbl->histogram.multival);
+
   err = (err != MDBX_NOTFOUND) ? chk_error_rc(scope, err, "mdbx_cursor_get") : MDBX_SUCCESS;
   if (err == MDBX_SUCCESS && record_count != db->items)
     chk_scope_issue(scope, "different number of entries %" PRIuSIZE " != %" PRIu64, record_count, db->items);
 bailout:
   if (cursor) {
     if (handler) {
-      if (tbl->histogram.key_len.count) {
+      if (record_count) {
         MDBX_chk_line_t *line = chk_line_begin(scope, MDBX_chk_info);
         line = histogram_dist(line, &tbl->histogram.key_len, "key length density", "0/1", false);
         chk_line_feed(line);
         line = histogram_dist(line, &tbl->histogram.val_len, "value length density", "0/1", false);
+        if (tbl->histogram.multival.amount) {
+          chk_line_feed(line);
+          line = histogram_dist(line, &tbl->histogram.multival, "number of multi-values density", "single", false);
+          chk_line_feed(line);
+          line = chk_print(line, "number of keys %" PRIuSIZE ", average values per key %.1f",
+                           tbl->histogram.multival.count, record_count / (double)tbl->histogram.multival.count);
+        }
         chk_line_end(line);
       }
       if (scope->stage == MDBX_chk_maindb)