如何优化我的 Firebird SQL 查询？

Question

数据库：Firebird 3.0

此查询用于 select 符合特定条件的记录，以检测哪些 DEVICEID 的 LAST_TICK 大于 DEVICEID={INTEGER VALUE} 知道其他 DEVICEID 的

这里是 SQL 查询：

select 
    a.TABELA, 
    a.DEVICEID,
    (select LAST_TICK from KNOWLEDGE b where b.DEVICEID={INTEGER VALUE} and b.CROSSID=a.DEVICEID and b.TABELA=a.TABELA) as MEU_TICK,
    max(LAST_TICK) as MAX_TICK 
from 
    KNOWLEDGE a 
where 
    a.DEVICEID=a.CROSSID 
group by
    a.TABELA, a.DEVICEID 
having 
    max(LAST_TICK) > (select LAST_TICK from KNOWLEDGE b where b.DEVICEID={INTEGER VALUE} and b.CROSSID=a.DEVICEID and b.TABELA=a.TABELA) 
order by 
    a.TABELA

只有11条记录的性能统计；

Plan
PLAN (B INDEX (PK_KNOWLEDGE))
PLAN (B INDEX (PK_KNOWLEDGE))
PLAN SORT (A NATURAL)

------ Performance info ------
Prepare time = 0ms
Execute time = 0ms
Current memory = 36.473.632
Max memory = 36.729.200
Memory buffers = 2.048
Reads from disk to cache = 0
Writes from cache to disk = 0
Fetches from cache = 65

Select Expression
-> Singularity Check
    -> Filter
        -> Table "KNOWLEDGE" as "B" Access By ID
            -> Bitmap
                -> Index "PK_KNOWLEDGE" Unique Scan
Select Expression
-> Singularity Check
    -> Filter
        -> Table "KNOWLEDGE" as "B" Access By ID
            -> Bitmap
                -> Index "PK_KNOWLEDGE" Unique Scan
Select Expression
-> Filter
    -> Aggregate
        -> Sort (record length: 214, key length: 176)
            -> Filter
                -> Table "KNOWLEDGE" as "A" Full Scan

*** 编辑 1： DDL：

CREATE TABLE KNOWLEDGE (
DEVICEID   "INTEGER" NOT NULL /* "INTEGER" = INTEGER */,
TABELA     VARCHAR40 NOT NULL /* VARCHAR40 = VARCHAR(40) */,
CROSSID    "INTEGER" NOT NULL /* "INTEGER" = INTEGER */,
LAST_TICK  "INTEGER" NOT NULL /* "INTEGER" = INTEGER */
);
ALTER TABLE KNOWLEDGE ADD CONSTRAINT PK_KNOWLEDGE PRIMARY KEY (DEVICEID, TABELA, CROSSID);
CREATE INDEX KNOWLEDGE_IDX1 ON KNOWLEDGE (TABELA);
CREATE INDEX KNOWLEDGE_IDX2 ON KNOWLEDGE (DEVICEID, CROSSID);

示例数据：

INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (4, 'PESSOAS', 4, 11);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (4, 'PESSOAS', 5, 47);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (4, 'PESSOAS', 6, 118);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (4, 'PESSOAS', 7, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (4, 'PESSOAS', 8, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (4, 'PESSOAS', 9, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (4, 'PESSOAS', 10, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (4, 'PESSOAS', 11, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (4, 'PESSOAS', 12, 5);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (5, 'PESSOAS', 4, 11);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (5, 'PESSOAS', 5, 47);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (5, 'PESSOAS', 6, 118);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (5, 'PESSOAS', 7, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (5, 'PESSOAS', 8, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (5, 'PESSOAS', 9, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (5, 'PESSOAS', 10, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (5, 'PESSOAS', 11, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (5, 'PESSOAS', 12, 5);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (6, 'PESSOAS', 4, 11);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (6, 'PESSOAS', 5, 47);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (6, 'PESSOAS', 6, 118);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (6, 'PESSOAS', 7, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (6, 'PESSOAS', 8, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (6, 'PESSOAS', 9, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (6, 'PESSOAS', 10, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (6, 'PESSOAS', 11, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (6, 'PESSOAS', 12, 5);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (7, 'PESSOAS', 4, 11);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (7, 'PESSOAS', 5, 47);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (7, 'PESSOAS', 6, 118);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (7, 'PESSOAS', 7, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (7, 'PESSOAS', 8, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (7, 'PESSOAS', 9, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (7, 'PESSOAS', 10, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (7, 'PESSOAS', 11, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (7, 'PESSOAS', 12, 5);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (8, 'PESSOAS', 4, 11);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (8, 'PESSOAS', 5, 47);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (8, 'PESSOAS', 6, 118);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (8, 'PESSOAS', 7, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (8, 'PESSOAS', 8, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (8, 'PESSOAS', 9, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (8, 'PESSOAS', 10, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (8, 'PESSOAS', 11, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (8, 'PESSOAS', 12, 5);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (9, 'PESSOAS', 4, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (9, 'PESSOAS', 5, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (9, 'PESSOAS', 6, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (9, 'PESSOAS', 7, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (9, 'PESSOAS', 8, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (9, 'PESSOAS', 9, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (9, 'PESSOAS', 10, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (9, 'PESSOAS', 11, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (9, 'PESSOAS', 12, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (10, 'PESSOAS', 4, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (10, 'PESSOAS', 5, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (10, 'PESSOAS', 6, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (10, 'PESSOAS', 7, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (10, 'PESSOAS', 8, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (10, 'PESSOAS', 9, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (10, 'PESSOAS', 10, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (10, 'PESSOAS', 11, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (10, 'PESSOAS', 12, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (11, 'PESSOAS', 4, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (11, 'PESSOAS', 5, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (11, 'PESSOAS', 6, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (11, 'PESSOAS', 7, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (11, 'PESSOAS', 8, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (11, 'PESSOAS', 9, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (11, 'PESSOAS', 10, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (11, 'PESSOAS', 11, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (11, 'PESSOAS', 12, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (12, 'PESSOAS', 4, 11);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (12, 'PESSOAS', 5, 47);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (12, 'PESSOAS', 6, 118);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (12, 'PESSOAS', 7, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (12, 'PESSOAS', 8, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (12, 'PESSOAS', 9, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (12, 'PESSOAS', 10, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (12, 'PESSOAS', 11, 0);
INSERT INTO KNOWLEDGE (DEVICEID, TABELA, CROSSID, LAST_TICK)
           VALUES (12, 'PESSOAS', 12, 10);

COMMIT WORK;

逻辑细节：

用于数据同步算法。此知识 table 包含系统中注册的每个设备的知识（上次更新时间），并将其存储在服务器中。客户端设备连接到服务器并发送更新的记录，服务器更新其知识 table 以反映这些变化。然后其他客户端设备连接到服务器以获取这些更改并更新其本地数据库。

知识的逻辑table是这样的：

D-嘿服务器，我是设备 4，我想知道是否有新的东西给我？

S-K，稍等，我查一下。嘿数据库服务器，从知识 table 中获取所有记录，即 DEVICEID 的 LAST_TICK 比我自己的知识 (CROSSID=DEVICEID) 更高，同时在该查询中放入设备自己的知识，因此它服务器更容易为这些记录构建查询。

DB- 当然，这是列表

S- 很好，现在从这些 table 中获取所有那些 update_tick 高于设备 4 知识的记录。

Db- 是的，就是这样。

S-嘿设备，获取这些记录并更新它

d- np，完成。谢谢大佬..

使用上面提供的测试数据，无论我们在 {INTEGER VALUE} 中提供什么设备 ID，结果都应该是包含值的单行： { TABELA: "PESSOAS", DEVICEID: 12, MEU_TICK: 5, MAX_TICK: 12}

Answer 1

您可以像这样创建一个 cte：

With cte_base AS (
select distinct LAST_TICK 
from KNOWLEDGE b 
where b.DEVICEID={INTEGER VALUE} and b.CROSSID=a.DEVICEID 
and b.TABELA=a.TABELA
)

select 
    a.TABELA, 
    a.DEVICEID,
    cte_base.LAST_TICK as MEU_TICK,
    max(LAST_TICK) as MAX_TICK 
from 
    KNOWLEDGE a 
where 
    a.DEVICEID=a.CROSSID 
group by
    a.TABELA, a.DEVICEID 
having 
    max(LAST_TICK) > (cte_base.LAST_TICK) 
order by 
    a.TABELA

Answer 2

一项可能会提高性能的非常简单的更改正在更改

group by
    a.TABELA, a.DEVICEID

到

group by
    a.DEVICEID, a.TABELA

这将允许优化器使用 PK_KNOWLEDGE 进行聚合所需的排序。

将您的查询重写为：

可实现进一步优化

with max_tick as (
    select 
       TABELA,
       DEVICEID,
       MAX(LAST_TICK) as MAX_TICK
    from KNOWLEDGE
    where DEVICEID = CROSSID
    group by DEVICEID, TABELA
)
select 
   a.TABELA,
   a.DEVICEID,
   a.MAX_TICK,
   b.LAST_TICK AS MEU_TICK
from max_tick a
inner join KNOWLEDGE b 
   on a.DEVICEID = b.CROSSID AND a.TABELA = b.TABELA and a.MAX_TICK > b.LAST_TICK
where b.DEVICEID = {INTEGER VALUE}
order by a.TABELA

但我不能 100% 确定此查询是否等效，因为您的示例数据没有提供足够的变化来测试它。

如何优化我的 Firebird SQL 查询？

How can I optimize my Firebird SQL query?

sql

firebird

firebird-3.0