RediSearch FT.AGGREGATE为何将条目归入错误分组？

核心问题：LOAD参数格式错误 #

你的FT.AGGREGATE命令中，LOAD后的数字6是错误的。LOAD命令里指定的数字代表后续要加载的字段数量，你实际只加载了questions和answers两个字段，因此应该写LOAD 2，或者直接省略该数字（Redis会自动识别字段数量）。

错误的数字导致Redis解析字段时出现异常，进而让@questions和@answers的取值不符合预期，最终引发分组错误。

修正后的查询命令 #

FT.AGGREGATE mySearch @answeredBy:{John} LOAD 2 $.results[*].question AS questions $.results[*].answer AS answers GROUPBY 2 @questions @answers REDUCE COUNT 0 AS numAnswers DIALECT 4

或者省略数字：

FT.AGGREGATE mySearch @answeredBy:{John} LOAD $.results[*].question AS questions $.results[*].answer AS answers GROUPBY 2 @questions @answers REDUCE COUNT 0 AS numAnswers DIALECT 4

额外说明：若需统计单个问答对的出现次数 #

如果你的真实需求是统计John回答过的每个问答对的总次数（比如「Who is a composer? -> Bach」出现2次，「Who is an athlete? -> Tiger Woods」出现1次），需要用UNWIND展开数组，而非直接加载整个数组：

FT.AGGREGATE mySearch @answeredBy:{John} LOAD $.results AS results UNWIND @results AS result LOAD $.result.question AS question $.result.answer AS answer GROUPBY 2 @question @answer REDUCE COUNT 0 AS numAnswers DIALECT 4

该命令会把每个文档中的results数组拆分成单个问答对象，再按问答对分组计数，得到精准的统计结果。

内容的提问来源于stack exchange，提问作者goose_lake