CREATE TABLE `t100mb4a` (

  `a` varchar(1000) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci DEFAULT NULL,

  KEY `a` (`a`(575))

) ENGINE=Aria;

MariaDB [test]>  SELECT COUNT(*) FROM t100mb4a;

+----------+

| COUNT(*) |

+----------+

| 10001000 |

+----------+

MariaDB [test]> SELECT COUNT(DISTINCT a) FROM t100mb4a;

+-------------------+

| COUNT(DISTINCT a) |

+-------------------+

|            999665 |

+-------------------+

+---------------------------+----------------+----------------+

| VARIABLE_NAME             | SESSION_VALUE  | GLOBAL_VALUE   |

+---------------------------+----------------+----------------+

| TMP_MEMORY_TABLE_SIZE     | 16777216       | 16777216       |

| HISTOGRAM_SIZE            | 254            | 254            |

| MAX_HEAP_TABLE_SIZE       | 1048576        | 1048576        |

| HISTOGRAM_TYPE            | DOUBLE_PREC_HB | DOUBLE_PREC_HB |

| ANALYZE_SAMPLE_PERCENTAGE | 100.000000     | 100.000000     |

+---------------------------+----------------+----------------+

set @@rand_seed1=1, @@rand_seed2=333;

ANALYZE TABLE t100mb4a PERSISTENT FOR COLUMNS (a) INDEXES ();

select db_name, table_name, column_name, min_value, max_value, nulls_ratio, avg_length, avg_frequency, hist_size, hist_type, hex(histogram) from mysql.column_stats where db_name="test" and table_name="t100mb4a"\G

       db_name: test

    table_name: t100mb4a

   column_name: a

     min_value: !ѩᜃ昔뤙檂儰���䤱锪㽇綡또ᒯ䙶∃흩췄繘ສ쾇ḁ븬宛遂븵օ嬿⃘錺糘뛋᪯扇鬖辰ⶬ㘈蕢䥵蛎앨䗜ු瑎ᭋⱉ诋㕛栣桞톫���퐵笽⪊ᄈ홊﬛揩˸欝歀휩ぅắࣙ탮棌∟烳츢댔ᒽ

     max_value: ￿���倅࢏㭹཯魾���烑ꖙ鳠哇툁ᩯས﹬젯䰧둔ꁰӴ㢲ౚ鑭쁒Δ튪ზ���⅞์䟿볘흺ﺚ燓㸏걜륢馔폼噳㔈،翢沆鼵

   nulls_ratio: 0.0000

    avg_length: 224.1367

 avg_frequency: 10.0044

     hist_size: 254

     hist_type: DOUBLE_PREC_HB

hex(histogram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

       db_name: test

    table_name: t100mb4a

   column_name: a

     min_value: !ѩᜃ昔뤙檂儰���䤱锪㽇綡또ᒯ䙶∃흩췄繘ສ쾇ḁ븬宛遂븵օ嬿⃘錺糘뛋᪯扇鬖辰ⶬ㘈蕢䥵蛎앨䗜ු瑎ᭋⱉ诋㕛栣桞톫���퐵笽⪊ᄈ홊﬛揩˸欝歀휩ぅắࣙ탮棌∟烳츢댔ᒽ

     max_value: ￿���倅࢏㭹཯魾���烑ꖙ鳠哇툁ᩯས﹬젯䰧둔ꁰӴ㢲ౚ鑭쁒Δ튪ზ���⅞์䟿볘흺ﺚ燓㸏걜륢馔폼噳㔈،翢沆鼵

   nulls_ratio: 0.0000

    avg_length: 224.1367

 avg_frequency: 1.0843

     hist_size: 254

     hist_type: DOUBLE_PREC_HB

hex(histogram): 2000200020002000200020002400240024002400240000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000