我试图确定每列大表中的总存储量。它有多个nvarchar。
一列是nvarchar（max），在导入时，XML的文本放在其中。正确处理记录后。该列再次清空为空字符串。
在SQL Server“顶级表的磁盘使用情况”报告中，我看到以下内容。
金额记录：1 808 604
保留（KB）：15 209 272
数据（KB）：14 466 776
指数（KB）：731 896
未使用（KB）：10 600
所以我正在寻找如何找到表中大量数据的位置。因为nvarchar（max）列几乎都是空的。
我对该表中的所有列进行了求和（datalength（columnname））。并将所有列值相加。
这给了我：499 344 838字节= 0.499344838千兆字节
所以我现在想知道：
编辑：我已经完成了一些插入数据的测试（参见下面的循环）
通过这个测试，它没有那么多的数据差异，+ - 23 vs 27 MB。
我将尝试在生产表上进行重建，但我需要安排它。
Edit2：我做了一个循环测试1000次：插入100 + set xml =''其中xml <>''结果之后是264.008KB数据。如果我那么重建，它会下降到22.944KB。
所以看起来重建可以提供解决方案。但是对于这对生产环境的密集程度有什么想法吗？如果我需要执行它，是否可以在我的应用程序中检测到它？
带索引的表定义
CREATE TABLE [dbo].[BATCH](
[BATCH_PID] [bigint] IDENTITY(1,1) NOT NULL,
[XML_CREATION_DATE] [datetime] NULL,
[BATCH_REFERENCE] [nvarchar](50) NULL,
[SOURCE] [nvarchar](50) NULL,
[DOCUMENT_CLASS_FID] [int] NULL,
[XML_NAME] [nvarchar](150) NULL,
[XML_TYPE] [int] NULL,
[XML] [nvarchar](max) NULL,
[NUM_OF_DOCUMENTS] [int] NULL,
[NUM_OF_IMAGES] [int] NULL,
[PRIORITY] [int] NULL,
[STATUS] [int] NULL,
[USER_FID] [int] NULL,
[EXTENAL_USER] [nvarchar](50) NULL,
[REMARKS] [nvarchar](max) NULL,
[XML_PATH] [nvarchar](max) NULL,
[BATCH_CREATION_DATE] [datetime] NULL,
[BATCH_PROCESS_DATE] [datetime] NULL,
[Action] [int] NULL,
[IMPORT_LOCATION_FID] [bigint] NULL,
[QUARANTINE_LOCATION_FID] [bigint] NULL,
[QUARANTINE_DATE] [datetime] NULL,
[QUARANTINE] [bit] NULL,
[DOCS_ON_ERROR] [varchar](255) NULL,
[CAPTURE_XML] [nvarchar](max) NULL,
[IGNORE_PAC] [bit] NULL,
[APPLICATION] [int] NULL,
[EXTRA_INFO] [nvarchar](max) NULL,
[INPUT_TEXT] [nvarchar](max) NULL,
[PROCESS_TIME_BATCH] [int] NULL,
[PROCESS_TIME_DOCUMENT] [int] NULL,
[PROCESS_TIME_IMAGE] [int] NULL,
[BATCH_SIZE] [int] NULL,
[RULES] [nvarchar](1000) NULL,
[KEEP_XML] [bit] NULL,
PRIMARY KEY CLUSTERED
(
[BATCH_PID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
CREATE NONCLUSTERED INDEX [IDX_BATCH_Action] ON [dbo].[BATCH]
(
[Action] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO
CREATE NONCLUSTERED INDEX [IDX_BATCH_BATCH_CREATION_DATE] ON [dbo].[BATCH]
(
[BATCH_CREATION_DATE] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO
CREATE NONCLUSTERED INDEX [IDX_BATCH_BATCH_SIZE] ON [dbo].[BATCH]
(
[BATCH_SIZE] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO
CREATE NONCLUSTERED INDEX [IDX_BATCH_DOCUMENT_CLASS_FID] ON [dbo].[BATCH]
(
[DOCUMENT_CLASS_FID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO
CREATE NONCLUSTERED INDEX [IDX_BATCH_IMPORT_LOCATION_FID] ON [dbo].[BATCH]
(
[IMPORT_LOCATION_FID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO
CREATE NONCLUSTERED INDEX [IDX_BATCH_PRIORITY] ON [dbo].[BATCH]
(
[PRIORITY] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO
CREATE NONCLUSTERED INDEX [IDX_BATCH_PROCESS_TIME_BATCH] ON [dbo].[BATCH]
(
[PROCESS_TIME_BATCH] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO
CREATE NONCLUSTERED INDEX [IDX_BATCH_PROCESS_TIME_DOCUMENT] ON [dbo].[BATCH]
(
[PROCESS_TIME_DOCUMENT] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO
CREATE NONCLUSTERED INDEX [IDX_BATCH_PROCESS_TIME_IMAGE] ON [dbo].[BATCH]
(
[PROCESS_TIME_IMAGE] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO
CREATE NONCLUSTERED INDEX [IDX_BATCH_QUARANTINE] ON [dbo].[BATCH]
(
[QUARANTINE] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO
CREATE NONCLUSTERED INDEX [IDX_BATCH_QUARANTINE_LOCATION_FID] ON [dbo].[BATCH]
(
[QUARANTINE_LOCATION_FID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO
SET ANSI_PADDING ON
GO
CREATE NONCLUSTERED INDEX [IDX_BATCH_SOURCE] ON [dbo].[BATCH]
(
[SOURCE] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO
CREATE NONCLUSTERED INDEX [IDX_BATCH_STATUS] ON [dbo].[BATCH]
(
[STATUS] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO
CREATE NONCLUSTERED INDEX [IDX_BATCH_USER_FID] ON [dbo].[BATCH]
(
[USER_FID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO
SET ANSI_PADDING ON
GO
CREATE NONCLUSTERED INDEX [IDX_BATCH_XML_NAME] ON [dbo].[BATCH]
(
[XML_NAME] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO
我还创建了一个简单的循环来插入数据
declare @numInserts int = 10000
declare @buildvarchar int = 10000
declare @maxvarchar nvarchar(max) = N'X'
begin
while @buildvarchar > 0
begin
set @maxvarchar = @maxvarchar + N'X'
set @buildvarchar = @buildvarchar - 1
end
while @numInserts > 0
begin
INSERT [dbo].[BATCH] ([XML_CREATION_DATE], [BATCH_REFERENCE], [SOURCE], [DOCUMENT_CLASS_FID], [XML_NAME], [XML_TYPE], [XML], [NUM_OF_DOCUMENTS], [NUM_OF_IMAGES], [PRIORITY], [STATUS], [USER_FID], [EXTENAL_USER], [REMARKS], [XML_PATH], [BATCH_CREATION_DATE], [BATCH_PROCESS_DATE], [Action], [IMPORT_LOCATION_FID], [QUARANTINE_LOCATION_FID], [QUARANTINE_DATE], [QUARANTINE], [DOCS_ON_ERROR], [CAPTURE_XML], [IGNORE_PAC], [APPLICATION], [EXTRA_INFO], [INPUT_TEXT], [PROCESS_TIME_BATCH], [PROCESS_TIME_DOCUMENT], [PROCESS_TIME_IMAGE], [BATCH_SIZE], [RULES], [KEEP_XML])
VALUES (CAST(N'2017-09-21T14:56:46.000' AS DateTime), N'', N'iDesk', 1, N'21-09-2017-14-44-58-501574', 2,
@maxvarchar, 0, 0, 1, 9, 1, N'', N'', N'D:\BaseDir\', CAST(N'2017-09-21T14:56:46.000' AS DateTime), CAST(N'2017-09-21T14:56:46.000' AS DateTime), 3, 1, 0, CAST(N'1900-01-01T00:00:00.000' AS DateTime), 0, N'1', NULL, NULL, 4, NULL, N'', 412, 0, 0, 0, N'', 0)
set @numInserts = @numInserts - 1
end
end
通过以下声明，我设法将表大小减小到27GB。
ALTER TABLE批处理REBUILD WITH（ONLINE = OFF）
看起来SQL不会自动重用空间。
我没有找到解决方案，如何检测它是否会提前清理。 sum数据长度查询差异就像400MB差异。
•是否无法用sum计算内容的大小（datalength（..））
创建只包含一列和一个值的表。
CREATE TABLE [dbo].[BATCH2] ([BATCH_PID] INT)
INSERT INTO [BATCH2] VALUES (1)
SELECT DATALENGTH(BATCH_PID) FROM BATCH2
这将返回4，因为我们知道INT Storage是4 byte。
如果我们使用，sp_spaceused BATCH2
您会注意到数据列是8KB。为什么？
我们知道数据存储在页面中，每页占用8KB。
所以在我们的例子中，即使一行也需要1页，即8KB。
因此datalength将为您提供大小数据。
•该计算是否正确，报告中使用的其他+ - 14GB在哪里？
如果我们第一次插入10000行，然后说删除/更新一些长度不一的行，那么sp_spaceused BATCH2可能无法返回正确的值，因为内存不能用Insert/Update/Delete回收。当我们删除某些行或更新某些行时，可能会有一些未使用的行页面中的内存，或者由于大量更新可能会有更多页面。
但它不会立即反映出来。
所以我们不时需要Rebuild Index专门用这么多索引表。
因此，一旦我们重建索引，索引是orgainise，数据在数据页和索引页中组织，丢失的内存被回收。
ALTER INDEX ALL ON [dbo].[BATCH] reorganize
所以sp_spaceused BATCH现在会提供正确的数据。