SphinxSearch完全匹配排名(SphinxSearch exact match ranking)

 我注意到使用Sphinx 2.2.8的排序顺序中有一个奇怪的行为（与v2.3.1-beta相同的结果）。 
 
 我希望精确匹配出现在第一个位置（我为此设置了index_exact_words和expan_keywords）。 
 
 这对我下面的第一个例子有两行有效。 但是如果我添加更多行，权重会更改，我的完全匹配结果（id = 1）会比其他近似值更低！ 
 
 例如，索引这两个单词（一些带有形态学libstemmer_fr的法语单词）： 
 
source nptest
{
        type                    = pgsql
        sql_host                = localhost
        sql_user                = myuser
        sql_pass                = mypassword
        sql_db                  = mydb
        sql_port                = 5432

        sql_query               = \
                                  SELECT 1, 'chien' AS val \
                                  UNION \
                                  SELECT 2, 'chienne'

        sql_field_string = val
}

index nptest
{
        type                    = plain
        mlock                   = 1
        source                  = nptest
        path                    = /var/lib/sphinx/data/nptest
        morphology              = libstemmer_fr
        index_exact_words       = 1
        expand_keywords         = 1
}
 
 索引后（indexer --rotate nptest）： 
 
mysql> SELECT id, val, weight() FROM nptest WHERE match('chien');
+------+---------+----------+
| id   | val     | weight() |
+------+---------+----------+
|    1 | chien   |     1500 |
|    2 | chienne |     1428 |
+------+---------+----------+
2 rows in set (0.00 sec)
 
 “chien”这个词的排名高于“chienne”=>这就是我的预期。 
 
 现在我向db添加更多行： 
 
source nptest
{
        type                    = pgsql
        sql_host                = localhost
        sql_user                = myuser
        sql_pass                = mypassword
        sql_db                  = mydb
        sql_port                = 5432

        sql_query               = \
                SELECT 1, 'chien' AS val \
                UNION \
                SELECT 2, 'chienne' \
                UNION \
                SELECT 3, 'un beau chien' \
                UNION \
                SELECT 4, 'chien-loup'

        sql_field_string = val
}


mysql> SELECT id, val, weight() FROM nptest WHERE match('chien');
+------+---------------+----------+
| id   | val           | weight() |
+------+---------------+----------+
|    2 | chienne       |     1402 |
|    1 | chien         |     1373 |
|    3 | un beau chien |     1373 |
|    4 | chien-loup    |     1373 |
+------+---------------+----------+
4 rows in set (0.00 sec)
 
 重新索引后，最高级别现在是“chienne”！ 
 
 这是正常的行为（如果是这样的原因？）或者它是一个错误？ 如果它不是错误，我怎样才能确保完全匹配将获得最高排名？ 

I noticed a strange behavior in the sort order using Sphinx 2.2.8 (same result with v2.3.1-beta).
 
I expect exact matching to appear on first position (I set index_exact_words and expan_keywords for that).
 
That works well on my first example below with two rows. But if I add more rows, weights change and my exact match result (id=1) gets a lower rank than other approximate one!
 
For example, indexing these 2 words (some french words with morphology libstemmer_fr):
 
source nptest
{
        type                    = pgsql
        sql_host                = localhost
        sql_user                = myuser
        sql_pass                = mypassword
        sql_db                  = mydb
        sql_port                = 5432

        sql_query               = \
                                  SELECT 1, 'chien' AS val \
                                  UNION \
                                  SELECT 2, 'chienne'

        sql_field_string = val
}

index nptest
{
        type                    = plain
        mlock                   = 1
        source                  = nptest
        path                    = /var/lib/sphinx/data/nptest
        morphology              = libstemmer_fr
        index_exact_words       = 1
        expand_keywords         = 1
}
 
After indexing (indexer --rotate nptest):
 
mysql> SELECT id, val, weight() FROM nptest WHERE match('chien');
+------+---------+----------+
| id   | val     | weight() |
+------+---------+----------+
|    1 | chien   |     1500 |
|    2 | chienne |     1428 |
+------+---------+----------+
2 rows in set (0.00 sec)
 
The word "chien" has a higher rank than "chienne" => that's what I expected.
 
Now I add more rows to my db:
 
source nptest
{
        type                    = pgsql
        sql_host                = localhost
        sql_user                = myuser
        sql_pass                = mypassword
        sql_db                  = mydb
        sql_port                = 5432

        sql_query               = \
                SELECT 1, 'chien' AS val \
                UNION \
                SELECT 2, 'chienne' \
                UNION \
                SELECT 3, 'un beau chien' \
                UNION \
                SELECT 4, 'chien-loup'

        sql_field_string = val
}


mysql> SELECT id, val, weight() FROM nptest WHERE match('chien');
+------+---------------+----------+
| id   | val           | weight() |
+------+---------------+----------+
|    2 | chienne       |     1402 |
|    1 | chien         |     1373 |
|    3 | un beau chien |     1373 |
|    4 | chien-loup    |     1373 |
+------+---------------+----------+
4 rows in set (0.00 sec)
 
After reindexing the highest rank is now on "chienne"!
 
Is this a normal behaviour (if so why?) or is it a bug? If it is not a bug, how can I ensure that exact matching will get the highest rank ?

原文：https://stackoverflow.com/questions/29073517