【中文说明】用于根据数据库表结构、慢查询和执行计划评估 SQL 索引方案，重点处理复合索引顺序、覆盖列、可搜索性和冗余风险。使用时粘贴 schema、SQL、EXPLAIN 输出及数据库类型，模型会按等值、排序、范围条件分析建议，并指出低选择性或重复索引的代价。 Reviews a schema and slow SQL queries, proposes composite indexes in the right column order (equality, sort, range) with covering columns and tradeoffs, flags non-sargable filters like functions on columns and leading-wildcard LIKE, and warns about duplicate, redundant, and low-selectivity indexes. Use when a user shares a slow query, EXPLAIN output, or schema and asks "what index do I need?" or "too many indexes?". Includes a tested stdlib Python helper.
