日付でソートされた和集合 CTE に基づいて前の行の値を返すのは遅いです。
<p>从以下的体育比赛表格中：</p>
<table class="s-table">
<thead>
<tr>
<th>id_</th>
<th>p1_id</th>
<th>p2_id</th>
<th>match_date</th>
<th>p1_stat</th>
<th>p2_stat</th>
</tr>
</thead>
<tbody>
<tr>
<td>852666</td>
<td>1</td>
<td>2</td>
<td>01/01/1997</td>
<td>1301</td>
<td>249</td>
</tr>
<tr>
<td>852842</td>
<td>1</td>
<td>2</td>
<td>13/01/1997</td>
<td>2837</td>
<td>2441</td>
</tr>
<tr>
<td>853471</td>
<td>2</td>
<td>1</td>
<td>05/05/1997</td>
<td>1474</td>
<td>952</td>
</tr>
<tr>
<td>4760</td>
<td>2</td>
<td>1</td>
<td>25/05/1998</td>
<td>1190</td>
<td>1486</td>
</tr>
<tr>
<td>6713</td>
<td>2</td>
<td>1</td>
<td>18/01/1999</td>
<td>2084</td>
<td>885</td>
</tr>
<tr>
<td>9365</td>
<td>2</td>
<td>1</td>
<td>01/11/1999</td>
<td>2894</td>
<td>2040</td>
</tr>
<tr>
<td>11456</td>
<td>1</td>
<td>2</td>
<td>15/05/2000</td>
<td>2358</td>
<td>1491</td>
</tr>
<tr>
<td>13022</td>
<td>1</td>
<td>2</td>
<td>14/08/2000</td>
<td>2722</td>
<td>2401</td>
</tr>
<tr>
<td>29159</td>
<td>1</td>
<td>2</td>
<td>26/08/2002</td>
<td>431</td>
<td>2769</td>
</tr>
<tr>
<td>44915</td>
<td>1</td>
<td>2</td>
<td>07/10/2002</td>
<td>1904</td>
<td>482</td>
</tr>
</tbody>
</table>
<p>对于选定的比赛id_，我希望返回两位选手在他们各自上一场比赛中的统计数据，无论该选手在上一场比赛中是p1还是p2。请参考下面的预期输出，其中id_ = 11456：</p>
<table class="s-table">
<thead>
<tr>
<th>id_</th>
<th>p1_id</th>
<th>p2_id</th>
<th>match_date</th>
<th>p1_stat</th>
<th>p2_stat</th>
<th>p1_prev_stat</th>
<th>p2_prev_stat</th>
</tr>
</thead>
<tbody>
<tr>
<td>11456</td>
<td>1</td>
<td>2</td>
<td>15/05/2000</td>
<td>2358</td>
<td>1491</td>
<td>2040</td>
<td>2894</td>
</tr>
</tbody>
</table>
<p>在这个大小的表上，以下的SQL语句完全正常运行：</p>
<pre class="brush:php;toolbar:false;">WITH cte_1 AS (
(
SELECT
id_,
match_date,
p1_id AS player_id,
p1_stat AS stat
FROM
test.match_table
UNION ALL
SELECT
id_,
match_date,
p2_id AS player_id,
p2_stat AS stat
FROM
test.match_table
)
),
cte_2 AS (
SELECT
id_,
player_id,
LAG(stat) OVER (
PARTITION BY player_id
ORDER BY
match_date,
id_
) AS prev_stat
FROM
cte_1
)
SELECT
m.*,
cte_p1.prev_stat AS p1_prev_stat,
cte_p2.prev_stat AS p2_prev_stat
FROM
test.match_table AS m
JOIN cte_2 AS cte_p1 ON cte_p1.id_ = m.id_
AND cte_p1.player_id = m.p1_id
JOIN cte_2 AS cte_p2 ON cte_p2.id_ = m.id_
AND cte_p2.player_id = m.p2_id
WHERE m.id_ = 11456
ORDER BY m.match_date</pre>
<p>然而，实际的表格有130万行，大约需要12秒的时间。根据这个回答，问题似乎是CTE加载了所有或大部分的表格行，而不仅仅是需要的行。然而，解决方案并没有涵盖这种情况。</p><p>是否有人能提供一些建议，以改善性能？、</p><p>以下是创建小表格的SQL语句：</p><p><br /></p>
<pre class="brush:php;toolbar:false;">CREATE TABLE `match_table` (
`id_` int NOT NULL AUTO_INCREMENT,
`p1_id` int NOT NULL,
`p2_id` int NOT NULL,
`match_date` date NOT NULL,
`p1_stat` int DEFAULT NULL,
`p2_stat` int DEFAULT NULL,
PRIMARY KEY (`id_`),
KEY `ix__p1_id` (`p1_id`),
KEY `ix__p2_id` (`p2_id`),
KEY `ix__match_date` (`match_date`),
KEY `ix__comp` (`p1_id`, `p2_id`, `match_date`)
);
INSERT INTO `match_table`
VALUES
(
4760, 2, 1, '1998-05-25', 1190, 1486
),
(6713, 2, 1, '1999-01-18', 2084, 885),
(
9365, 2, 1, '1999-11-01', 2894, 2040
),
(
11456, 1, 2, '2000-05-15', 2358, 1491
),
(
13022, 1, 2, '2000-08-14', 2722, 2401
),
(
29159, 1, 2, '2002-08-26', 431, 2769
),
(
44915, 1, 2, '2002-10-07', 1904, 482
),
(
852666, 1, 2, '1997-01-01', 1301, 249
),
(
852842, 1, 2, '1997-01-13', 2837, 2441
),
(
853471, 2, 1, '1997-05-05', 1474, 952
);</pre>
