如何解决CTE被多次呼叫了?
我的任务是调查一个非常慢的SQL查询。如果我对CTE的理解是正确的,则每次在外部查询中调用CTE时都会调用它们。
WITH
UserAccount
AS
(
SELECT uaa.AccountId FROM Paymentinitiation.UserAccountAccess uaa
WHERE uaa.UserId = @userId
),CTE_TransactionId (TransactionId)
AS
(
SELECT TOP 100 TransactionId
FROM Paymentinitiation.TransactionMetaDataDebit T
JOIN UserAccount UA ON T.AccountId = UA.AccountId
WHERE T.TransactionId < @seekPoint ORDER BY T.TransactionId DESC
)
SELECT
PT.Id,InstructionId,ContractReference,CpgReference,ModuleTypeId,ProductType,PT.ModifiedAt,VirtualAccountId,CounterpartyExchangeRate
FROM Paymentinitiation.PaymentTransactions PT
JOIN CTE_TransactionId P ON PT.Id = P.TransactionId
此查询将导致执行计划带有嵌套循环和大量执行。
所以我的问题确实是-CTE是否由于在集合中的earch行上执行而导致查询阻塞?
还是我看错了?
非常感谢。
解决方法
我认为您希望得到这样的结果
with CTE_TransactionId (TransactionId) AS (
SELECT TOP 100 TransactionId
FROM PaymentInitiation.UserAccountAccess uaa
join PaymentInitiation.TransactionMetaDataDebit T on uaa.AccountId=T.AccountId
WHERE UAA.UserId=@userId
and T.TransactionId < @seekPoint
ORDER BY T.TransactionId DESC)
SELECT
PT.Id,InstructionId,ContractReference,CpgReference,ModuleTypeId,ProductType,PT.ModifiedAt,VirtualAccountId,CounterpartyExchangeRate
FROM PaymentInitiation.PaymentTransactions PT
join CTE_TransactionId P ON PT.Id = P.TransactionId;
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