分面搜索对于现代搜索应用来说,与自动补全、拼写纠正和搜索关键词高亮同样重要,尤其是在电子商务产品中。

当处理大量数据和各种相互关联的属性时,例如尺寸、颜色、制造商或其他因素,分面搜索就派上用场了。在查询海量数据时,搜索结果常常包含许多不符合用户预期的条目。分面搜索使最终用户能够明确定义他们希望搜索结果满足的条件。
在 Manticore Search 中,有一项优化功能,它会保留原始查询的结果集,并在每个分面计算中重复使用。由于聚合操作应用于已计算好的文档子集,因此速度很快,总执行时间通常仅比初始查询稍长一些。分面可以添加到任何查询中,分面可以是任何属性或表达式。分面结果包括分面值和分面计数。可以通过在查询末尾声明分面,使用 SQL SELECT 语句访问分面。
分面值可以来自属性、JSON 属性内的 JSON 属性或表达式。分面值也可以使用别名,但别名在所有结果集(主查询结果集和其他分面结果集)中必须是唯一的。分面值源自聚合的属性/表达式,但也可以来自另一个属性/表达式。
FACET {expr_list} [BY {expr_list} ] [DISTINCT {field_name}] [ORDER BY {expr | FACET()} {ASC | DESC}] [LIMIT [offset,] count]
多个分面声明必须用空格分隔。
分面可以在 aggs 节点中定义:
"aggs" :
{
"group name" :
{
"terms" :
{
"field":"attribute name",
"size": 1000
}
"sort": [ {"attribute name": { "order":"asc" }} ]
}
}
其中:
group name是分配给聚合的别名field值必须包含要进行分面的属性或表达式的名称- 可选的
size指定结果中包含的最大桶数。未指定时,继承主查询的限制。更多详细信息可以在分面结果大小部分找到。 - 可选的
sort指定一个属性数组和/或附加属性,使用与主查询中的"sort"参数相同的语法。
结果集将包含一个 aggregations 节点,其中包含返回的分面,key 是聚合值,doc_count 是聚合计数。
"aggregations": {
"group name": {
"buckets": [
{
"key": 10,
"doc_count": 1019
},
{
"key": 9,
"doc_count": 954
},
{
"key": 8,
"doc_count": 1021
},
{
"key": 7,
"doc_count": 1011
},
{
"key": 6,
"doc_count": 997
}
]
}
}
- SQL
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SELECT *, price AS aprice FROM facetdemo LIMIT 10 FACET price LIMIT 10 FACET brand_id LIMIT 5;+------+-------+----------+---------------------+------------+-------------+---------------------------------------+------------+--------+
| id | price | brand_id | title | brand_name | property | j | categories | aprice |
+------+-------+----------+---------------------+------------+-------------+---------------------------------------+------------+--------+
| 1 | 306 | 1 | Product Ten Three | Brand One | Six_Ten | {"prop1":66,"prop2":91,"prop3":"One"} | 10,11 | 306 |
| 2 | 400 | 10 | Product Three One | Brand Ten | Four_Three | {"prop1":69,"prop2":19,"prop3":"One"} | 13,14 | 400 |
...
| 9 | 560 | 6 | Product Two Five | Brand Six | Eight_Two | {"prop1":90,"prop2":84,"prop3":"One"} | 13,14 | 560 |
| 10 | 229 | 9 | Product Three Eight | Brand Nine | Seven_Three | {"prop1":84,"prop2":39,"prop3":"One"} | 12,13 | 229 |
+------+-------+----------+---------------------+------------+-------------+---------------------------------------+------------+--------+
10 rows in set (0.00 sec)
+-------+----------+
| price | count(*) |
+-------+----------+
| 306 | 7 |
| 400 | 13 |
...
| 229 | 9 |
| 595 | 10 |
+-------+----------+
10 rows in set (0.00 sec)
+----------+----------+
| brand_id | count(*) |
+----------+----------+
| 1 | 1013 |
| 10 | 998 |
| 5 | 1007 |
| 8 | 1033 |
| 7 | 965 |
+----------+----------+
5 rows in set (0.00 sec)可以通过聚合另一个属性或表达式对数据进行分面。例如,如果文档同时包含品牌ID和名称,我们可以在分面中返回品牌名称,但聚合品牌ID。这可以通过使用 FACET {expr1} BY {expr2} 来实现。
- SQL
SELECT * FROM facetdemo FACET brand_name by brand_id;+------+-------+----------+---------------------+-------------+-------------+---------------------------------------+------------+
| id | price | brand_id | title | brand_name | property | j | categories |
+------+-------+----------+---------------------+-------------+-------------+---------------------------------------+------------+
| 1 | 306 | 1 | Product Ten Three | Brand One | Six_Ten | {"prop1":66,"prop2":91,"prop3":"One"} | 10,11 |
| 2 | 400 | 10 | Product Three One | Brand Ten | Four_Three | {"prop1":69,"prop2":19,"prop3":"One"} | 13,14 |
....
| 19 | 855 | 1 | Product Seven Two | Brand One | Eight_Seven | {"prop1":63,"prop2":78,"prop3":"One"} | 10,11,12 |
| 20 | 31 | 9 | Product Four One | Brand Nine | Ten_Four | {"prop1":79,"prop2":42,"prop3":"One"} | 12,13,14 |
+------+-------+----------+---------------------+-------------+-------------+---------------------------------------+------------+
20 rows in set (0.00 sec)
+-------------+----------+
| brand_name | count(*) |
+-------------+----------+
| Brand One | 1013 |
| Brand Ten | 998 |
| Brand Five | 1007 |
| Brand Nine | 944 |
| Brand Two | 990 |
| Brand Six | 1039 |
| Brand Three | 1016 |
| Brand Four | 994 |
| Brand Eight | 1033 |
| Brand Seven | 965 |
+-------------+----------+
10 rows in set (0.00 sec)如果需要从 FACET 返回的桶中移除重复项,可以使用 DISTINCT field_name,其中 field_name 是您希望用于去重的字段。如果您对分布式表进行 FACET 查询,并且不确定表中是否有唯一的ID(表应该是本地的且具有相同的模式),也可以是 id(这是默认值)。
如果查询中有多个 FACET 声明,field_name 在所有声明中应该相同。
DISTINCT 会在 count(*) 列之前返回一个额外的列 count(distinct ...),使您无需进行另一个查询即可获得两个结果。
- SQL
- JSON
SELECT brand_name, property FROM facetdemo FACET brand_name distinct property;+-------------+----------+
| brand_name | property |
+-------------+----------+
| Brand Nine | Four |
| Brand Ten | Four |
| Brand One | Five |
| Brand Seven | Nine |
| Brand Seven | Seven |
| Brand Three | Seven |
| Brand Nine | Five |
| Brand Three | Eight |
| Brand Two | Eight |
| Brand Six | Eight |
| Brand Ten | Four |
| Brand Ten | Two |
| Brand Four | Ten |
| Brand One | Nine |
| Brand Four | Eight |
| Brand Nine | Seven |
| Brand Four | Five |
| Brand Three | Four |
| Brand Four | Two |
| Brand Four | Eight |
+-------------+----------+
20 rows in set (0.00 sec)
+-------------+--------------------------+----------+
| brand_name | count(distinct property) | count(*) |
+-------------+--------------------------+----------+
| Brand Nine | 3 | 3 |
| Brand Ten | 2 | 3 |
| Brand One | 2 | 2 |
| Brand Seven | 2 | 2 |
| Brand Three | 3 | 3 |
| Brand Two | 1 | 1 |
| Brand Six | 1 | 1 |
| Brand Four | 4 | 5 |
+-------------+--------------------------+----------+
8 rows in set (0.00 sec)- SQL
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SELECT * FROM facetdemo FACET INTERVAL(price,200,400,600,800) AS price_range ;+------+-------+----------+---------------------+-------------+-------------+---------------------------------------+------------+-------------+
| id | price | brand_id | title | brand_name | property | j | categories | price_range |
+------+-------+----------+---------------------+-------------+-------------+---------------------------------------+------------+-------------+
| 1 | 306 | 1 | Product Ten Three | Brand One | Six_Ten | {"prop1":66,"prop2":91,"prop3":"One"} | 10,11 | 1 |
...
+------+-------+----------+---------------------+-------------+-------------+---------------------------------------+------------+-------------+
20 rows in set (0.00 sec)
+-------------+----------+
| price_range | count(*) |
+-------------+----------+
| 0 | 1885 |
| 3 | 1973 |
| 4 | 2100 |
| 2 | 1999 |
| 1 | 2043 |
+-------------+----------+
5 rows in set (0.01 sec)- SQL
SELECT *,INTERVAL(price,200,400,600,800) AS price_range FROM facetdemo
FACET price_range AS price_range,brand_name ORDER BY brand_name asc;+------+-------+----------+---------------------+-------------+-------------+---------------------------------------+------------+-------------+
| id | price | brand_id | title | brand_name | property | j | categories | price_range |
+------+-------+----------+---------------------+-------------+-------------+---------------------------------------+------------+-------------+
| 1 | 306 | 1 | Product Ten Three | Brand One | Six_Ten | {"prop1":66,"prop2":91,"prop3":"One"} | 10,11 | 1 |
...
+------+-------+----------+---------------------+-------------+-------------+---------------------------------------+------------+-------------+
20 rows in set (0.00 sec)
+--------------+-------------+----------+
| fprice_range | brand_name | count(*) |
+--------------+-------------+----------+
| 1 | Brand Eight | 197 |
| 4 | Brand Eight | 235 |
| 3 | Brand Eight | 203 |
| 2 | Brand Eight | 201 |
| 0 | Brand Eight | 197 |
| 4 | Brand Five | 230 |
| 2 | Brand Five | 197 |
| 1 | Brand Five | 204 |
| 3 | Brand Five | 193 |
| 0 | Brand Five | 183 |
| 1 | Brand Four | 195 |
...Facets可以通过构造固定大小的桶来对值进行直方图聚合。 键函数是:
key_of_the_bucket = interval + offset * floor ( ( value - offset ) / interval )
直方图参数interval必须为正数,直方图参数offset必须为正数且小于interval。默认情况下,桶以数组形式返回。直方图参数keyed使得响应以字典形式返回桶键。
- SQL
- JSON
- JSON 2
SELECT COUNT(*), HISTOGRAM(price, {hist_interval=100}) as price_range FROM facets GROUP BY price_range ORDER BY price_range ASC;+----------+-------------+
| count(*) | price_range |
+----------+-------------+
| 5 | 0 |
| 5 | 100 |
| 1 | 300 |
| 4 | 400 |
| 1 | 500 |
| 3 | 700 |
| 1 | 900 |
+----------+-------------+Facets可以对日期直方图值进行聚合,这与普通直方图类似。不同之处在于,区间由日期或时间表达式指定。此类表达式需要特殊支持,因为区间长度不总是固定的。值会根据以下键函数四舍五入到最近的桶:
key_of_the_bucket = interval * floor ( value / interval )
直方图参数calendar_interval理解月份具有不同的天数。
与calendar_interval不同,fixed_interval参数使用固定数量的单位,无论其在日历中的位置如何,都不会偏离。但是fixed_interval无法处理如周或月这样的单位,因为月不是一个固定数量。尝试为fixed_interval指定如周或月这样的单位将导致错误。
接受的区间在日期直方图表达式中描述。默认情况下,桶以数组形式返回。直方图参数keyed使得响应以字典形式返回桶键。
- SQL
- JSON
SELECT count(*), DATE_HISTOGRAM(tm, {calendar_interval='month'}) AS months FROM idx_dates GROUP BY months ORDER BY months ASC+----------+------------+
| count(*) | months |
+----------+------------+
| 442 | 1485907200 |
| 744 | 1488326400 |
| 720 | 1491004800 |
| 230 | 1493596800 |
+----------+------------+- SQL
- JSON
- JSON 2
SELECT COUNT(*), RANGE(price, {range_to=150},{range_from=150,range_to=300},{range_from=300}) price_range FROM facets GROUP BY price_range ORDER BY price_range ASC;+----------+-------------+
| count(*) | price_range |
+----------+-------------+
| 8 | 0 |
| 2 | 1 |
| 10 | 2 |
+----------+-------------+Facets可以对一组日期范围进行聚合,这与普通范围类似。不同之处在于,from和to值可以使用日期数学表达式表示。此聚合包括from值并排除每个范围的to值。将keyed属性设置为true使得响应以字典形式返回桶键,而不是数组。
- SQL
- JSON
SELECT COUNT(*), DATE_RANGE(tm, {range_to='2017||+2M/M'},{range_from='2017||+2M/M',range_to='2017||+5M/M'},{range_from='2017||+5M/M'}) AS points FROM idx_dates GROUP BY points ORDER BY points ASC;+----------+--------+
| count(*) | points |
+----------+--------+
| 442 | 0 |
| 1464 | 1 |
| 230 | 2 |
+----------+--------+Facets支持ORDER BY子句,就像标准查询一样。每个Facet可以有自己的排序方式,Facet的排序不会影响主结果集的排序,这由主查询的ORDER BY决定。排序可以基于属性名、计数(使用COUNT(*)、COUNT(DISTINCT attribute_name))或特殊的FACET()函数,该函数提供聚合数据值。默认情况下,带有ORDER BY COUNT(*)的查询将按降序排序。
- SQL
- JSON
SELECT * FROM facetdemo
FACET brand_name BY brand_id ORDER BY FACET() ASC
FACET brand_name BY brand_id ORDER BY brand_name ASC
FACET brand_name BY brand_id order BY COUNT(*) DESC;
FACET brand_name BY brand_id order BY COUNT(*);+------+-------+----------+---------------------+-------------+-------------+---------------------------------------+------------+
| id | price | brand_id | title | brand_name | property | j | categories |
+------+-------+----------+---------------------+-------------+-------------+---------------------------------------+------------+
| 1 | 306 | 1 | Product Ten Three | Brand One | Six_Ten | {"prop1":66,"prop2":91,"prop3":"One"} | 10,11 |
...
| 20 | 31 | 9 | Product Four One | Brand Nine | Ten_Four | {"prop1":79,"prop2":42,"prop3":"One"} | 12,13,14 |
+------+-------+----------+---------------------+-------------+-------------+---------------------------------------+------------+
20 rows in set (0.01 sec)
+-------------+----------+
| brand_name | count(*) |
+-------------+----------+
| Brand One | 1013 |
| Brand Two | 990 |
| Brand Three | 1016 |
| Brand Four | 994 |
| Brand Five | 1007 |
| Brand Six | 1039 |
| Brand Seven | 965 |
| Brand Eight | 1033 |
| Brand Nine | 944 |
| Brand Ten | 998 |
+-------------+----------+
10 rows in set (0.01 sec)
+-------------+----------+
| brand_name | count(*) |
+-------------+----------+
| Brand Eight | 1033 |
| Brand Five | 1007 |
| Brand Four | 994 |
| Brand Nine | 944 |
| Brand One | 1013 |
| Brand Seven | 965 |
| Brand Six | 1039 |
| Brand Ten | 998 |
| Brand Three | 1016 |
| Brand Two | 990 |
+-------------+----------+
10 rows in set (0.01 sec)
+-------------+----------+
| brand_name | count(*) |
+-------------+----------+
| Brand Six | 1039 |
| Brand Eight | 1033 |
| Brand Three | 1016 |
| Brand One | 1013 |
| Brand Five | 1007 |
| Brand Ten | 998 |
| Brand Four | 994 |
| Brand Two | 990 |
| Brand Seven | 965 |
| Brand Nine | 944 |
+-------------+----------+
10 rows in set (0.01 sec)默认情况下,每个Facet结果集仅限于20个值。可以通过LIMIT子句单独为每个Facet控制Facet值的数量,提供返回值的数量格式LIMIT count或使用偏移量LIMIT offset, count。
返回的最大Facet值数量受查询的max_matches设置限制。如果您想实现动态max_matches(限制max_matches为偏移量+每页以提高性能),必须考虑到过低的max_matches值可能会影响Facet值的数量。在这种情况下,应使用足以覆盖Facet值数量的最小max_matches值。
- SQL
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SELECT * FROM facetdemo
FACET brand_name BY brand_id ORDER BY FACET() ASC LIMIT 0,1
FACET brand_name BY brand_id ORDER BY brand_name ASC LIMIT 2,4
FACET brand_name BY brand_id order BY COUNT(*) DESC LIMIT 4;+------+-------+----------+---------------------+-------------+-------------+---------------------------------------+------------+
| id | price | brand_id | title | brand_name | property | j | categories |
+------+-------+----------+---------------------+-------------+-------------+---------------------------------------+------------+
| 1 | 306 | 1 | Product Ten Three | Brand One | Six_Ten | {"prop1":66,"prop2":91,"prop3":"One"} | 10,11 |
...
| 20 | 31 | 9 | Product Four One | Brand Nine | Ten_Four | {"prop1":79,"prop2":42,"prop3":"One"} | 12,13,14 |
+------+-------+----------+---------------------+-------------+-------------+---------------------------------------+------------+
20 rows in set (0.01 sec)
+-------------+----------+
| brand_name | count(*) |
+-------------+----------+
| Brand One | 1013 |
+-------------+----------+
1 rows in set (0.01 sec)
+-------------+----------+
| brand_name | count(*) |
+-------------+----------+
| Brand Four | 994 |
| Brand Nine | 944 |
| Brand One | 1013 |
| Brand Seven | 965 |
+-------------+----------+
4 rows in set (0.01 sec)
+-------------+----------+
| brand_name | count(*) |
+-------------+----------+
| Brand Six | 1039 |
| Brand Eight | 1033 |
| Brand Three | 1016 |
+-------------+----------+
3 rows in set (0.01 sec)当使用SQL时,带有 facets 的搜索会返回多个结果集。MySQL客户端/库/连接器所使用的 必须 支持多个结果集,以便访问 facets 结果集。
内部,FACET 是执行多查询的一个快捷方式,其中第一个查询包含主要搜索查询,批次中的其余查询各自包含聚类。正如多查询的情况一样,对于带有 facets 的搜索,常见的查询优化可以启动,这意味着搜索查询只执行一次,而 facets 则在搜索查询结果上操作,每个 facet 只增加总查询时间的一小部分。
要检查 facets 搜索是否以优化模式运行,可以在 查询日志 中查找,其中所有记录的查询将包含一个 xN 字符串,N 是优化组中运行的查询数量。或者,可以检查 SHOW META 语句的输出,该语句将显示一个 multiplier 指标:
- SQL
SELECT * FROM facetdemo FACET brand_id FACET price FACET categories;
SHOW META LIKE 'multiplier';+------+-------+----------+---------------------+-------------+-------------+---------------------------------------+------------+
| id | price | brand_id | title | brand_name | property | j | categories |
+------+-------+----------+---------------------+-------------+-------------+---------------------------------------+------------+
| 1 | 306 | 1 | Product Ten Three | Brand One | Six_Ten | {"prop1":66,"prop2":91,"prop3":"One"} | 10,11 |
...
+----------+----------+
| brand_id | count(*) |
+----------+----------+
| 1 | 1013 |
...
+-------+----------+
| price | count(*) |
+-------+----------+
| 306 | 7 |
...
+------------+----------+
| categories | count(*) |
+------------+----------+
| 10 | 2436 |
...
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| multiplier | 4 |
+---------------+-------+
1 row in set (0.00 sec)