ジョインが多いほど、PSQLクエリの結果は少なくなります

Question

次のpsqlテーブルがあります。実際には、およそ20億行があります。

id word  lemma  pos    textid country_genre  
1 Stuffing stuff  vvg    190568 AN   
2 her  her  appge   190568 AN   
3 key  key  nn1    190568 AN   
4 into  into  ii    190568 AN   
5 the  the  at    190568 AN   
6 lock  lock  nn1    190568 AN   
7 she  she  appge   190568 AN   
8 pushed  push  vvd    190568 AN   
9 her  her  appge   190568 AN   
10 way  way  nn1    190568 AN   
11 into  into  ii    190568 AN   
12 the  the  appge   190568 AN   
13 house  house  nn1    190568 AN   
14 .      .    190568 AN   
15 She  she  appge   190568 AN   
16 had  have  vhd    190568 AN   
17 also  also  rr    190568 AN   
18 cajoled cajole  vvd    190568 AN   
19 her  her  appge   190568 AN   
20 way  way  nn1    190568 AN   
21 into  into  ii    190568 AN   
22 the  the  at    190568 AN   
23 home  home  nn1    190568 AN   
24 .      .    190568 AN   
.. ...  ...  ..    ...  .. 

私は言葉のサイド・バイ・サイドですべての「道」-idiomsといくつかの列「country_genre」、「補題」からのデータと「POS」を示しており、以下の表を作成したいと思います。

country_genre word word  word  lemma  pos  word  word  word  word  word  lemma  pos  word  word  
AN   lock she  pushed  push  vvd  her  way  into  the  house  house  nn1  .   she 
AN   had also  cajoled cajole  vvd  her  way  into  the  home  home  nn1  .   A   
AN   tried to   force  force  vvi  her  way  into  the  palace  palace  nn1  ,   officials 

私は（ボヘミアンのおかげ：https://stackoverflow.com/a/47496945/3957383！）：次のコードを使用し

copy(

SELECT 
    c1.id, c1.country_genre, c1.textid, c1.wordid, c1.word, c2.word, c3.word, c4.word, c4.lemma, c4.pos, c5.word, c6.word, c7.word, c8.word, c9.word, c9.lemma, c9.pos, c10.word, c11.word 

FROM 

orderedflatcorpus AS c1 
JOIN orderedflatcorpus AS c2 ON c1.id + 1 = c2.id 
JOIN orderedflatcorpus AS c3 ON c1.id + 2 = c3.id 
JOIN orderedflatcorpus AS c4 ON c1.id + 3 = c4.id 
JOIN orderedflatcorpus AS c5 ON c1.id + 4 = c5.id 
JOIN orderedflatcorpus AS c6 ON c1.id + 5 = c6.id 
JOIN orderedflatcorpus AS c7 ON c1.id + 6 = c7.id 
JOIN orderedflatcorpus AS c8 ON c1.id + 7 = c8.id 
JOIN orderedflatcorpus AS c9 ON c1.id + 8 = c9.id 
JOIN orderedflatcorpus AS c10 ON c1.id + 9 = c10.id 
JOIN orderedflatcorpus AS c11 ON c1.id + 10 = c11.id 

WHERE 

c4.pos LIKE 'vv%' 
AND c5.pos = 'appge' 
AND c6.word = 'way' 
AND c7.pos LIKE 'i%' 
AND c8.word = 'the' 
AND c9.pos LIKE 'n%' 
) 

TO 

'/home/postgres/Results/OUTPUT.csv' 
DELIMITER E'\t' 
csv header; 

このクエリは、18706体の関連構造を返します。

Iはよりコンテキスト（代わりに11ワードの21）を抽出するが、以前のものとそうでない場合は等しく、次のコードを使用する場合は、心配何かが起こる：私は18555関連構造を得ます。

copy(
SELECT c1.id, c1.country_genre, c1.textid, c1.wordid, c1.word, c1.pos, c2.word, c2.pos, c3.word, c3.pos, c4.word, c4.pos, c5.word, c5.pos, c6.word, c6.pos, 
c7.word, c7.pos, c8.word, c8.pos, c8.lemma, c9.word, c9.pos, c10.word, c10.pos, c11.word, c11.pos, c12.word, c12.pos, c13.word, c13.pos, c13.lemma, c14.word, 
c14.pos, c15.word, c15.pos, c16.word, c16.pos, c17.word, c17.pos, c18.word, c18.pos, c19.word, c19.pos, c20.word, c20.pos, c21.word, c21.pos 

FROM 

orderedflatcorpus AS c1 
JOIN orderedflatcorpus AS c2 ON c1.id + 1 = c2.id 
JOIN orderedflatcorpus AS c3 ON c1.id + 2 = c3.id 
JOIN orderedflatcorpus AS c4 ON c1.id + 3 = c4.id 
JOIN orderedflatcorpus AS c5 ON c1.id + 4 = c5.id 
JOIN orderedflatcorpus AS c6 ON c1.id + 5 = c6.id 
JOIN orderedflatcorpus AS c7 ON c1.id + 6 = c7.id 
JOIN orderedflatcorpus AS c8 ON c1.id + 7 = c8.id 
JOIN orderedflatcorpus AS c9 ON c1.id + 8 = c9.id 
JOIN orderedflatcorpus AS c10 ON c1.id + 9 = c10.id 
JOIN orderedflatcorpus AS c11 ON c1.id + 10 = c11.id 
JOIN orderedflatcorpus AS c12 ON c1.id + 11 = c12.id 
JOIN orderedflatcorpus AS c13 ON c1.id + 12 = c13.id 
JOIN orderedflatcorpus AS c14 ON c1.id + 13 = c14.id 
JOIN orderedflatcorpus AS c15 ON c1.id + 14 = c15.id 
JOIN orderedflatcorpus AS c16 ON c1.id + 15 = c16.id 
JOIN orderedflatcorpus AS c17 ON c1.id + 16 = c17.id 
JOIN orderedflatcorpus AS c18 ON c1.id + 17 = c18.id 
JOIN orderedflatcorpus AS c19 ON c1.id + 18 = c19.id 
JOIN orderedflatcorpus AS c20 ON c1.id + 19 = c20.id 
JOIN orderedflatcorpus AS c21 ON c1.id + 20 = c21.id 

WHERE 

c8.pos LIKE 'vv%' 
AND c9.pos = 'appge' 
AND c10.word = 'way' 
AND c11.pos LIKE 'i%' 
AND c12.word = 'the' 
AND c13.pos LIKE 'n%' 
) 
TO '/home/postgres/Results/OUTPUT.csv' DELIMITER E'\t' csv header; 

2番目のクエリで見つからない行は見ましたが、除外されているパターンは検出できません。

いずれかがここで起こっかもしれないもののアイデアを持っていますか？ありがとう！

Answer 1

PostgresJOINは、INNER JOINに相当する。例えば、thisを参照してください。

言い換えれば、あなたのクエリが結果を持っているすべてのONの述語との一致が必要です。さらにJOINSを追加すると、一致しなかった述語​​がONとなり、結果の量が減少します。

JOINからLEFT JOIN（別名LEFT OUTER JOIN）に変更して、より多くの結果が得られるかどうかを確認してください。あなたの例のデータと結果から欠落しているものの例を見ずに

は、問題になる可能性がある他に何を言うのは難しいですし。

Answer 2

ピルホの答えは正しい - 限り、それまで通ります。ただし、外部結合への結合を変更するだけでは問題が解決されないことがあります。

まず、2つのクエリのためのwhere条件が異なっているので、私は、彼らが同じ結果セットを返すことを前提とする理由がありません。

2番目のクエリは、行に正確に21ワードを探している - ない19ワードではなく、13ワード。したがって、パターンがドキュメントの終わりにある場合、パターンは見つかりません。

あなたの条件に基づいて、行に表示する必要がある13語があります（あなたの条件に「13」を得るためには、私は推測しています、オプションの7行です。そして外部結合：

FROM orderedflatcorpus c1 JOIN 
    orderedflatcorpus c2 
    ON c1.id + 1 = c2.id JOIN 
    orderedflatcorpus c3 
    ON c1.id + 2 = c3.id JOIN 
    orderedflatcorpus c4 
    ON c1.id + 3 = c4.id JOIN 
    orderedflatcorpus c5 
    ON c1.id + 4 = c5.id JOIN 
    orderedflatcorpus c6 
    ON c1.id + 5 = c6.id JOIN 
    orderedflatcorpus c7 
    ON c1.id + 6 = c7.id JOIN 
    orderedflatcorpus c8 
    ON c1.id + 7 = c8.id JOIN 
    orderedflatcorpus c9 
    ON c1.id + 8 = c9.id JOIN 
    orderedflatcorpus c10 
    ON c1.id + 9 = c10.id JOIN 
    orderedflatcorpus c11 
    ON c1.id + 10 = c11.id JOIN 
    orderedflatcorpus c12 
    ON c1.id + 11 = c12.id JOIN 
    orderedflatcorpus c13 
    ON c1.id + 12 = c13.id 
    orderedflatcorpus c14 
    ON c1.id + 13 = c14.id LEFT JOIN 
    orderedflatcorpus c15 
    ON c1.id + 14 = c15.id LEFT JOIN 
    orderedflatcorpus c16 
    ON c1.id + 15 = c16.id LEFT JOIN 
    orderedflatcorpus c17 
    ON c1.id + 16 = c17.id LEFT JOIN 
    orderedflatcorpus c18 
    ON c1.id + 17 = c18.id LEFT JOIN 
    orderedflatcorpus c19 
    ON c1.id + 18 = c19.id LEFT JOIN 
    orderedflatcorpus c20 
    ON c1.id + 19 = c20.id LEFT JOIN 
    orderedflatcorpus c21 
    ON c1.id + 20 = c21.id 
WHERE c8.pos LIKE 'vv%' AND 
     c9.pos = 'appge' AND 
     c10.word = 'way' AND 
     c11.pos LIKE 'i%' AND 
     c12.word = 'the' AND 
     c13.pos LIKE 'n%' ; 

次へ：私はcountryおよび/またはtextidがjoin条件の一部であるべきと思われる