particularly novel, other options in the market provide fairly similar features in this particular respect (Vitess and CRDB). It is instead a combination of these market-defining focuses and additional features based on traffic and need, but most of these solutions do not automatically scale across nodes. Vitess CRDB PHXSQL 5 SPECIFIC FEATURES TIDB MYSQL COMPATIBILITY ECOSYSTEM REAL-TIME ANALYTICS HIGH LEVEL highlight that there exists a range of solutions that are up to date and supported. So for example Vitess has an Operator tool, this lacks support which results in issues while trying to set it up with

merge MySQL shards into TiDB· · · · · · · · · · · · · · · · · · · · · · 788 6.1.4 Migrate data from Vitess to TiDB · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 788 6.1.5 Migrate data from Migrate and Merge MySQL Shards of Large Datasets to TiDB · · · · · · · 835 6.4.6 Migrate Data from Vitess to TiDB · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 853 6.4.7 Migrate Data from Large Datasets to TiDB 6.1.4 Migrate data from Vitess to TiDB To migrate data from Vitess to TiDB, the following guide is available: • Migrate Data from Vitess to TiDB 6.1.5 Migrate data from files to TiDB

从大数据量分库分表 MySQL 合并迁移数据到 TiDB · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · 648 6.4.6 从 Vitess 迁移数据到 TiDB · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · DM 进行增量数据 (Binlog) 的分 表同步。 • 从大数据量分库分表 MySQL 合并迁移数据到 TiDB 6.1.3.1 将数据从 Vitess 迁移到 TiDB 将数据从 Vitess 迁移到 TiDB，可参考以下文档： • 从 Vitess 迁移数据到 TiDB 6.1.4 从文件迁移数据到 TiDB • 从 CSV 文件迁移数据到 TiDB • 从 SQL 文件迁移数据到 6 从 Vitess 迁移数据到 TiDB 本文档介绍了将数据从 Vitess 迁移到 TiDB 时可以采用的工具。 由于 Vitess 的后端基于 MySQL，当从 Vitess 迁移数据到 TiDB 时，你可以直接使用 MySQL 适用的迁移数据工具， 如Dumpling、TiDB Lightning 和TiDB Data Migration (DM)。需要注意的是，针对 Vitess 中的每个分片，你都需要进行

disable this behavior, refer to Telemetry. 2.2.3 Improvements • TiDB – Support the built-in function VITESS_HASH() #23915 – Support pushing down data of the enumerated type to TiKV to improve perfor- mance information. VITESS_HASH( �→ str) The VITESS_HASH function returns the hash of a string that is compatible with Vitess’ HASH function. This is intended to help the data migration from Vitess. 12.11.4.19 this behavior, refer to Telemetry. 14.2.6.3 Improvements • TiDB – Support the built-in function VITESS_HASH() #23915 – Support pushing down data of the enumerated type to TiKV to improve perfor- mance

_expression_index | +--------------------------------------------+ | lower, md5, reverse, upper, vitess_hash | +--------------------------------------------+ 1 row in set (0.00 sec) 1780 For the functions the cluster. VITESS_HASH( �→ str) The VITESS_HASH function returns the hash of a string that is compatible with Vitess’ HASH function. This is intended to help the data migration from Vitess. 12.11.4.19 this behavior, refer to Telemetry. 14.5.6.3 Improvements • TiDB – Support the built-in function VITESS_HASH() #23915 – Support pushing down data of the enumerated type to TiKV to improve perfor- mance

_expression_index | +--------------------------------------------+ | lower, md5, reverse, upper, vitess_hash | +--------------------------------------------+ 1 row in set (0.00 sec) 1712 For the functions the cluster. VITESS_HASH( �→ str) The VITESS_HASH function returns the hash of a string that is compatible with Vitess’ HASH function. This is intended to help the data migration from Vitess. 12.11.4.19 this behavior, refer to Telemetry. 14.4.6.3 Improvements • TiDB – Support the built-in function VITESS_HASH() #23915 – Support pushing down data of the enumerated type to TiKV to improve perfor- mance

tidb_allow_function_for_expression_index New in v5.2.0 • Scope: NONE • Default value: lower, md5, reverse, upper, vitess_hash • This variable is used to show the functions that are allowed to be used for creating expression _expression_index | +--------------------------------------------+ | lower, md5, reverse, upper, vitess_hash | 2367 +--------------------------------------------+ 1 row in set (0.00 sec) For the functions the cluster. VITESS_HASH( �→ str) The VITESS_HASH function returns the hash of a string that is compatible with Vitess’ HASH function. This is intended to help the data migration from Vitess. 12.11.4.19

json_storage_size, json_type, json_unquote, json_ �→ valid, lower, md5, reverse, tidb_shard, upper, vitess_hash • This read-only variable is used to show the functions that are allowed to be used for creating JSON_TYPE() • JSON_UNQUOTE() • JSON_VALID() • LOWER() • MD5() • REVERSE() • TIDB_SHARD() • UPPER() • VITESS_HASH() For the functions that are not included in the above list, those functions are not fully utc_timestamp | | uuid | | uuid_short | | uuid_to_bin | | validate_password_strength | | version | | vitess_hash | | week | | weekday | | weekofyear | | weight_string | | xor | | year | | yearweek |

json_storage_size, json_type, json_unquote, json_ �→ valid, lower, md5, reverse, tidb_shard, upper, vitess_hash • This read-only variable is used to show the functions that are allowed to be used for creating JSON_TYPE() • JSON_UNQUOTE() • JSON_VALID() • LOWER() 4078 • MD5() • REVERSE() • TIDB_SHARD() • UPPER() • VITESS_HASH() For the functions that are not included in the above list, those functions are not fully utc_timestamp | | uuid | | uuid_short | | uuid_to_bin | | validate_password_strength | | version | | vitess_hash | | week | | weekday | | weekofyear | | weight_string | | xor | | year | | yearweek |

xpression_index | +--------------------------------------------+ | lower, md5, reverse, upper, vitess_hash | +--------------------------------------------+ 1 row in set (0.00 sec) 对于以上变量返回结果之外的函数 TS 函数用于在集群中查询 一组 SQL Digest 所对应的 SQL 语句的归一化形式 （即去除格式和参数后的形式）。 VITESS_HASH(str) VITESS_HASH 函数返回与 Vitess 的 HASH 函数兼容的 字符串哈希值，有助于从 Vitess 迁移数据。 12.11.4.19.1 示例 下面为部分以上函数的示例。 TIDB_DECODE_KEY TIDB_DECODE_KEY TiDB 在遥测中新增收集集群请求的运行状态，包括执行情况、失败情况等。 若要了解所收集的信息详情及如何禁用该行为，请参见遥测文档。 14.4.6.3 提升改进 • TiDB – 支持 VITESS_HASH() 函数 #23915 – 支持枚举类型下推到 TiKV ，提升 WHERE 子句中使用枚举类型时的性能 #23619 – 支持 RENAME USER 语法 #23648 –