Sphinx 实时分词索引搜索

我创建了一个索引：

index berni_filter2
{
    rt_mem_limit    = 512M
    type            = rt
    path            = /var/lib/sphinxsearch/data/berni_filter

    rt_attr_uint    = product_id
    rt_attr_uint    = store_id
    rt_field        = product_name
    rt_attr_json    = attributes

    prefix_fields   = product_name
    expand_keywords = 1
    min_infix_len   = 2
    dict            = keywords
}

我正在尝试使用 SphinxQL 按名称查找产品：

SELECT product_id FROM berni_filter2 WHERE store_id = 0 AND MATCH ('@product_name mothercare')

该查询运行良好，但我还想搜索“mother”以查找包含“mothercare”的产品。试过：

SELECT product_id FROM berni_filter2 WHERE store_id = 0 AND MATCH ('@product_name mother')
SELECT product_id FROM berni_filter2 WHERE store_id = 0 AND MATCH ('@product_name mother*')
SELECT product_id FROM berni_filter2 WHERE store_id = 0 AND MATCH ('@product_name *mother*')

我还将 min_infix_len 更改为 min_prefix_len。什么都不管用。