我有一个由以下文档组成的单桶(Couchbase Community 6.5版)。
employee {
type: "Employee"
}
X {
type: "X",
employeeId: string,
date: string
}
Y {
type: "Y",
employeeId: string,
date: string
}
Z {
type: "Z",
employeeId: string,
date: string
}
我需要得到两个日期之间与每个雇员相关联的文档总数(X,Y,Z)。
我写了下面的查询,可以使用,但执行时间很慢。
CREATE INDEX `index_X` ON `bucket`(`type`,`date`, `employeeId`)
WHERE type = "X"
CREATE INDEX `index_Y` ON `bucket`(`type`,`date`, `employeeId`)
WHERE type = "Y"
CREATE INDEX `index_Z` ON `bucket`(`type`,`date`, `employeeId`)
WHERE type = "Z"
SELECT META(employee).id,
x.totalX,
y.totalY,
z.totalZ,
FROM `bucket` employee
LEFT JOIN (
SELECT obj.employeeId,
COUNT(obj.employeeId) AS totalX
FROM `bucket` obj
WHERE obj.type = "X"
AND obj.date BETWEEN "startDate" AND "endDate"
GROUP BY obj.employeeId) x ON x.employeeId = META(employee).id
LEFT JOIN (
SELECT obj.employeeId,
COUNT(obj.employeeId) AS totalY
FROM `bucket` obj
WHERE obj.type = "Y"
AND obj.date BETWEEN "startDate" AND "endDate"
GROUP BY obj.employeeId) y ON y.employeeId = META(employee).id
LEFT JOIN (
SELECT obj.employeeId,
COUNT(obj.employeeId) AS totalZ
FROM `bucket` obj
WHERE obj.type = "Z"
AND obj.date BETWEEN "startDate" AND "endDate"
GROUP BY obj.employeeId) z ON z.employeeId = META(employee).id
WHERE employee.type = "Employee"
我也试过下面的方法,但这个查询完全超时!
CREATE INDEX `index_X` ON `bucket`(`type`,`date`, `employeeId`)
WHERE type = "X"
CREATE INDEX `index_Y` ON `bucket`(`type`,`date`, `employeeId`)
WHERE type = "Y"
CREATE INDEX `index_Z` ON `bucket`(`type`,`date`, `employeeId`)
WHERE type = "Z"
SELECT META(employee).id,
COUNT(x.employeeId),
COUNT(y.employeeId),
COUNT(z.employeeId)
FROM `bucket` employee
LEFT JOIN `bucket` x ON x.employeeId = META(employee).id
AND x.type = "X"
AND x.date BETWEEN "startDate" AND "endDate"
LEFT JOIN `bucket` y ON y.employeeId = META(employee).id
AND y.type = "Y"
AND y.date BETWEEN "startDate" AND "endDate"
LEFT JOIN `bucket` z ON z.employeeId = META(employee).id
AND z.type = "Z"
AND z.date BETWEEN "startDate" AND "endDate"
WHERE employee.type = "Employee"
GROUP BY META(employee).id
谁能给我一个更理想的路线?
对于这两个查询,我可以看到我的索引正在被使用,但我也可以在我的查询计划中看到,对于每一个连接,一个 "NestedLoopJoin "正在与前一个连接连锁。这可能是问题所在吗?
我还是个写n1ql查询的新手,想找出最有效的方法,所以欢迎任何建议。
CREATE INDEX `index_1` ON `agrigistics_dev`(`employeeId`, type, `date`) WHERE type IN ["X", "Y", "Z"];
SELECT META(employee).id,
SUM(CASE x.type = "X" THEN 1 ELSE 0 END) xcount,
SUM(CASE x.type = "Y" THEN 1 ELSE 0 END) ycount,
SUM(CASE x.type = "Z" THEN 1 ELSE 0 END) zcount
FROM `bucket` employee
LEFT JOIN `bucket` x
ON x.employeeId = META(employee).id AND x.type IN ["X", "Y", "Z"] AND x.date BETWEEN "startDate" AND "endDate"
WHERE employee.type = "Employee"
GROUP BY META(employee).id;
为了避免case-cade嵌套循环连接或连接爆炸,在这种情况下使用CTE(6.5)
CREATE INDEX `index_1` ON `agrigistics_dev`(type, date, `employeeId`) WHERE type IN ["X", "Y", "Z"];
WITH etype AS (SELECT x.employeeId,
SUM(CASE x.type = "X" THEN 1 ELSE 0 END) xcount,
SUM(CASE x.type = "Y" THEN 1 ELSE 0 END) ycount,
SUM(CASE x.type = "Z" THEN 1 ELSE 0 END) zcount
FROM `bucket` x
WHERE x.type IN ["X", "Y", "Z"] AND x.date BETWEEN "startDate" AND "endDate"
GROUP BY x.employeeId)
SELECT META(employee).id,
SUM(y.xcount) xcount,
SUM(y.ycount) ycount,
SUM(y.zcount) zcount
FROM `bucket` AS employee
LEFT JOIN etype AS y ON y.employeeId = META(employee).id
WHERE employee.type = "Employee"
GROUP BY META(employee).id;