Question

我可以使用哪种查询提示来提高OR查询的性能。

以下两个查询单独立即运行并返回0行。

SELECT * FROM AuditInfo ai
WHERE (ai.AppointmentIdForChange = 60231)
and ai.objectname = 'dbo.Appointments'

SELECT * FROM AuditInfo ai
WHERE (ai.AppointmentIdForKey = 60231)
and ai.objectname = 'dbo.Appointments'

AuditInfo是一个视图。

但是以下查询将永远运行（10分钟以上）

SELECT * FROM AuditInfo ai
WHERE (ai.AppointmentIdForKey= 60231 OR ai.AppointmentIdForChange = 60231)
and ai.objectname = 'dbo.Appointments'

我该如何改进？我可以使用查询提示吗？

在估计的执行计划中，我可以看到各个查询使用Key Looks，而带有OR语句的查询使用Index Seeks（占用了74％的成本）。

更新：

AuditInfo视图定义如下：

ALTER VIEW AuditInfo
AS
SELECT 
    ae.Id
    ,ae.AuditDateTime AS DateTime
    ,ae.ChangeTypeId
    ,ae.ObjectName
    ,aek.KeyName
    ,aek.KeyValue
    ,aek.KeyValueNumeric
    ,ae.UserId
    ,ae.HostName
    ,ae.ServerName
    ,aec.OldValue   
    ,(SELECT TOP 1 aecNewValue.OldValue AS Value
        FROM dbo.AuditEntries aeNewValue
        JOIN dbo.AuditEntryKeyValues aekNewValue ON aeNewValue.Id = aekNewValue.AuditEntryId AND aek.KeyName = aekNewValue.KeyName AND aek.KeyValueNumeric = aekNewValue.KeyValueNumeric
        JOIN dbo.AuditEntryChanges aecNewValue ON aeNewValue.Id = aecNewValue.AuditEntryId AND aec.ColumnName = aecNewValue.ColumnName
        WHERE aeNewValue.ChangeTypeId IN (0, 1) AND aeNewValue.AuditDateTime > ae.AuditDateTime AND aeNewValue.ObjectName = ae.ObjectName
        ORDER BY aeNewValue.AuditDateTime 
    ) AS NewValue
    ,appointmentForKey.AppointmentId AS AppointmentIdForKey, appointmentForChange.AppointmentId AS AppointmentIdForChange
FROM dbo.AuditEntries ae
JOIN dbo.AuditEntryKeyValues aek on ae.Id = aek.AuditEntryId
LEFT JOIN dbo.AuditEntryChanges aec on ae.Id = aec.AuditEntryId AND aec.ColumnName IN ('PatientId', 'AppointmentId')

-- Get AppointmentId
LEFT JOIN dbo.Appointments appointmentForKey ON aek.KeyName = 'AppointmentId' AND aek.KeyValueNumeric = appointmentForKey.AppointmentId
LEFT JOIN dbo.Appointments appointmentForChange ON aec.ColumnName = 'AppointmentId' AND aec.OldValueNumeric = appointmentForChange.AppointmentId

GROUP BY ae.Id, ae.AuditDateTime, ae.UserId, ae.ChangeTypeId, ae.ObjectName, ae.HostName, ae.ServerName, aek.KeyName, aek.KeyValue, aek.KeyValueNumeric, aec.OldValueNumeric, aec.OldValue, aec.ColumnName
,appointmentForKey.AppointmentId, appointmentForChange.AppointmentId

Answer 1

我知道您要求提供查询提示，但您可以将其作为两个带联合的查询

运行

SELECT * FROM AuditInfo ai
WHERE (ai.AppointmentIdForChange = 60231)
and ai.objectname = 'dbo.Appointments'
UNION
SELECT * FROM AuditInfo ai
WHERE (ai.AppointmentIdForKey = 60231)
and ai.objectname = 'dbo.Appointments'

至于它将在明天表演为了稳定，我会通过JOIN或OR取一个UNION 使用Union SQL可以一次执行一个，并且查询优化器获得愚蠢的可能性更小。

TSQL或查询计划提示

1 个答案: