How to make SQL Server indexes take up less space?

I have a database created by some application. The entire database is more than 50 GB, some problems with backups occur, and my task is to get this database as little as possible.

Especially one table is very large (22 gb), of which 16.5 gb are taken by indices, the remaining 5.5 gb is data. It contains a little over 12 million rows.

Could you tell me if it is possible to reduce indexes? I have already tried rebuilding, reorganizing, recreating a clustered index, dbcc cleantable. I also know that the nvarchar type takes twice as much as the varchar, so I changed the column type to varchar, but thanks to this I only saved about 2 gb (1 gb for data and 1 gb for indexes).

Here is the sql for this table (fld0 and fld1 are always NULL):

CREATE TABLE [dbo].[DOC8](
 [ASSOCIATION] [nvarchar](64) NULL DEFAULT (NULL),
 [DOCID] [char](32) NOT NULL,
 [FLD0] [nvarchar](255) NULL DEFAULT (NULL),
 [FLD1] [nvarchar](2048) NULL DEFAULT (NULL),
 [FLD10] [nvarchar](255) NULL DEFAULT (NULL),
 [FLD2] [nvarchar](32) NULL DEFAULT (NULL),
 [FLD3] [nvarchar](255) NULL DEFAULT (NULL),
 [FLD4] [nvarchar](255) NULL DEFAULT (NULL),
 [FLD5] [datetime] NULL DEFAULT (NULL),
 [FLD6] [nvarchar](255) NULL DEFAULT (NULL),
 [FLD7] [nvarchar](255) NULL DEFAULT (NULL),
 [FLD8] [nvarchar](255) NULL DEFAULT (NULL),
 [FLD9] [datetime] NULL DEFAULT (NULL),
 [PARENTID] [char](32) NULL DEFAULT (NULL),
 [POOLID] [char](32) NULL DEFAULT (NULL),
 [PROPERTIES] [ntext] NULL DEFAULT (NULL),
 [FLD11] [nvarchar](255) NULL DEFAULT (NULL),
 [FLD12] [nvarchar](255) NULL DEFAULT (NULL),
PRIMARY KEY CLUSTERED 
(
 [DOCID] 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]
GO
SET ANSI_PADDING OFF
GO
CREATE NONCLUSTERED INDEX [DOC8_IDX_0] ON [dbo].[DOC8] 
(
 [ASSOCIATION] ASC,
 [PARENTID] ASC,
 [POOLID] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
GO
CREATE NONCLUSTERED INDEX [DOC8_IDX_1] ON [dbo].[DOC8] 
(
 [POOLID] ASC,
 [FLD0] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
GO
CREATE NONCLUSTERED INDEX [DOC8_IDX_10] ON [dbo].[DOC8] 
(
 [POOLID] ASC,
 [FLD11] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
GO
CREATE NONCLUSTERED INDEX [DOC8_IDX_11] ON [dbo].[DOC8] 
(
 [POOLID] ASC,
 [FLD12] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
GO
CREATE NONCLUSTERED INDEX [DOC8_IDX_2] ON [dbo].[DOC8] 
(
 [POOLID] ASC,
 [FLD2] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
GO
CREATE NONCLUSTERED INDEX [DOC8_IDX_3] ON [dbo].[DOC8] 
(
 [POOLID] ASC,
 [FLD3] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
GO
CREATE NONCLUSTERED INDEX [DOC8_IDX_4] ON [dbo].[DOC8] 
(
 [POOLID] ASC,
 [FLD4] ASC,
 [FLD5] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
GO
CREATE NONCLUSTERED INDEX [DOC8_IDX_5] ON [dbo].[DOC8] 
(
 [POOLID] ASC,
 [FLD6] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
GO
CREATE NONCLUSTERED INDEX [DOC8_IDX_6] ON [dbo].[DOC8] 
(
 [POOLID] ASC,
 [FLD7] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
GO
CREATE NONCLUSTERED INDEX [DOC8_IDX_7] ON [dbo].[DOC8] 
(
 [POOLID] ASC,
 [FLD8] ASC,
 [FLD9] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
GO
CREATE NONCLUSTERED INDEX [DOC8_IDX_8] ON [dbo].[DOC8] 
(
 [POOLID] ASC,
 [FLD10] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
GO
CREATE NONCLUSTERED INDEX [DOC8_IDX_9] ON [dbo].[DOC8] 
(
 [PARENTID] ASC,
 [POOLID] ASC,
 [DOCID] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
GO
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5 answers

Looking at a table definition

Primary key:

  • You have a clustered char index (32). These 32 bytes are mapped to each non-clustered index.

Columns:

  • Why char (32)? โ†’ varchar (32)
  • Why nvarchar ()? โ†’ varchar
  • Why is the date? โ†’ smalldatetime
  • Why ntext? โ†’ varchar (max)

Indices:

  • Can you use INCLUDE and not have key columns.

Your main problem is the poor choice of a clustered index. If you cannot fix it, almost everything else is pointless: if you do not delete the data ...

varchar, 2 22 . 9%, , - . , nvarchar...

int, 28 . 3,7 (12 12 000 000 28), - . .

...

. , , , , 50 , . , ?

+6

, , , , - .

/ , , .

, , , . , , ( ), . , , , ( , , ) .

+4

, [POOLID], [FLD]? , .

, DOCID .. - GUIDS . , guid, char32, indecies , , microsoft , , .

+1

, : - 5 451 477 4 088 609 - 15 361 391 6 003 094

, ( , -):

  • 9 nvarchar varchar - : 4 460 305 , - 14 456 383
  • , - : 4 460 305 , - 9 592 320
  • char (32) varchar (32) ntext varchar (max) - : 4 088 609 , : 9 294 117
  • indentity, , DOCID char (32), DOCID, - : 4 088 609 MB, : 6 003 094

, :)

0

Source: https://habr.com/ru/post/1782570/


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