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小編給大家分享一下如何使用系統(tǒng)SQL實(shí)體自動(dòng)創(chuàng)建非聚集索引,相信大部分人都還不怎么了解,因此分享這篇文章給大家參考一下,希望大家閱讀完這篇文章后大有收獲,下面讓我們一起去了解一下吧!
一直以來(lái),關(guān)于索引的常見(jiàn)問(wèn)題是:判斷哪部分索引對(duì)保證數(shù)據(jù)庫(kù)的良好性能是必需的。在本文中,筆者將提供針對(duì)該問(wèn)題的解決方案。本文用例中的所有代碼都基于名為dm_db_missing_index_details
的 SQL Server 系統(tǒng)視圖。
在開(kāi)始安裝前,進(jìn)一步了解 dm_db_missing_index_details
會(huì)更有益處。
dm_db_missing_index_details
會(huì)返回缺失索引的細(xì)節(jié)信息。在本文中,我們將更關(guān)注以下幾列:
index_handle:它是一個(gè)獨(dú)特的跨服務(wù)器標(biāo)識(shí)符,并且標(biāo)志一個(gè)特定的缺失索引。
equality_columns:包含用于相等謂詞的所有列
inequality_columns:包含用于其他比較的所有列
included columns索引中所包含的查詢必要出現(xiàn)列
statement: 補(bǔ)充完整索引缺失的表名
本系統(tǒng)的實(shí)現(xiàn)基于以下三個(gè)實(shí)體:
一個(gè)可以計(jì)算出待創(chuàng)建索引名稱的簡(jiǎn)單函數(shù)
一個(gè)用于簡(jiǎn)化 dm_db_missing_index_details
的用戶視圖
一個(gè)為每個(gè)索引創(chuàng)建聲明的進(jìn)程
筆者選擇將這個(gè)系統(tǒng)分為三段進(jìn)程,但實(shí)際上合并存儲(chǔ)過(guò)程和視圖也是可行的。筆者之所以沒(méi)有選擇后一種做法是因?yàn)橄朐趧?chuàng)建索引之前先從業(yè)務(wù)邏輯檢查一下存在哪些索引。
函數(shù) fn_Index_CreateIndexName
在這個(gè)函數(shù)中,有三個(gè)輸入?yún)?shù):
@equality_columns @equality_columns @index_handlE
該函數(shù)的目的是為每個(gè)期望創(chuàng)建的索引都創(chuàng)建一個(gè)唯一名稱。
因此,首先拼接@equality_columns
和@equality_columns
兩個(gè)輸入變量,如果拼接后所得結(jié)果超過(guò)120個(gè)字符,那就截取至第120個(gè)字符。
為什么是120個(gè)字符?
因?yàn)樵赟QL Server中,命名最大長(zhǎng)度為128個(gè)字符。這個(gè)函數(shù)在 @index_handlE 名字結(jié)尾添加字段以便保證唯一的索引名。
CREATE FUNCTION [dbo].[fn_Index_CreateIndexName] (@equality_columns NVARCHAR(4000), _ @Inequality_columns NVARCHAR(4000), @index_handlE INT) RETURNS VARCHAR(128) AS BEGIN DECLARE @IndexName NVARCHAR(255) SET @IndexName = ISNULL(@equality_columns,@Inequality_columns) SET @IndexName = LTRIM(REPLACE(@IndexName,'[','_')) SET @IndexName = RTRIM(REPLACE(@IndexName,']','_')) SET @IndexName = REPLACE(@IndexName,',','') SET @IndexName = REPLACE(@IndexName,'_ _','_') IF LEN(@IndexName) > 120 BEGIN SET @IndexName = SUBSTRING(@IndexName,0,120) END SET @IndexName = @IndexName + CAST(@index_handlE AS NVARCHAR(15)) RETURN @IndexName END
視圖 vw_Index_MissingIndex
該視圖基于dm_db_missing_index_details
和 sys.databases 表,并使用fn_Index_CreateIndexName
函數(shù)來(lái)計(jì)算缺失的索引名。
CREATE VIEW [dbo].[vw_Index_MissingIndex] AS SELECT '[' + d.name + ']' as DBName, [dbo].[fn_Index_CreateIndexName]_ (mid.equality_columns,mid.Inequality_columns,mid.index_handlE) AS ID, REPLACE(mid.equality_columns,',',' ASC,') AS equality_columns, REPLACE(mid.Inequality_columns,',',' ASC,') AS Inequality_columns, mid.Included_columns, mid.[statement] FROM sys.dm_db_missing_index_details mid INNER JOIN sys.databases d on d.database_id = mid.database_id
存儲(chǔ)過(guò)程 usp_Index_MissingIndexCreationStatements
該存儲(chǔ)過(guò)程基于 vw_Index_MissingIndex
,并且輸出索引創(chuàng)建語(yǔ)句。
CREATE PROCEDURE [dbo].[usp_Index_MissingIndexCreationStatements] AS DECLARE @IndexCreationPlaceholder_Start AS NVARCHAR(MAX) DECLARE @IndexCreationPlaceholder_End AS NVARCHAR(MAX) -- PREPARE PLACEHOLDER SET @IndexCreationPlaceholder_Start = 'IF NOT EXISTS(SELECT * _ FROM {2}.sys.indexes WHERE [name] = ''IX_{0}'' ) BEGIN CREATE NONCLUSTERED INDEX [IX_{0}] ON {1}' SET @IndexCreationPlaceholder_End = ' 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] END;' + char(13) + char(10) -- STATEMENT CREATION SELECT DBName, CASE WHEN NOT mid.equality_columns IS NULL AND NOT mid.Inequality_columns IS NULL THEN REPLACE(REPLACE(REPLACE(@IndexCreationPlaceholder_Start,'{0}', _ mid.ID),'{1}',mid.[statement]),'{2}',mid.DBName) + ' ( ' + COALESCE(mid.equality_columns,'') + ' ASC,' + COALESCE(mid.Inequality_columns,'') + ' ASC )' + COALESCE('INCLUDE ( ' + mid.Included_columns + ' ) ','') + @IndexCreationPlaceholder_End WHEN mid.equality_columns IS NULL AND NOT mid.Inequality_columns IS NULL THEN REPLACE(REPLACE(REPLACE(@IndexCreationPlaceholder_Start,_ '{0}', mid.ID),'{1}',mid.[statement]),'{2}',mid.DBName) + ' ( ' + COALESCE(mid.Inequality_columns,'') + ' ASC ) ' + COALESCE('INCLUDE ( ' + mid.Included_columns + ' ) ','') + @IndexCreationPlaceholder_End WHEN NOT mid.equality_columns IS NULL AND mid.Inequality_columns IS NULL THEN REPLACE(REPLACE(REPLACE(@IndexCreationPlaceholder_Start,'{0}', _ mid.ID),'{1}',mid.[statement]),'{2}',mid.DBName) + ' ( ' + COALESCE(mid.equality_columns,'') + ' ASC ) ' + COALESCE('INCLUDE ( ' + mid.Included_columns + ' ) ','') + @IndexCreationPlaceholder_End ELSE NULL END AS Index_Creation_Statement, ' DROP INDEX [IX_' + mid.ID + '] ON ' + mid.[statement] _ + + char(13) + char(10) AS Index_Drop_Statement FROM [dbo].[vw_Index_MissingIndex] AS mid
-- CREATE FUNCTION fn_Index_CreateIndexName CREATE FUNCTION [dbo].[fn_Index_CreateIndexName] (@equality_columns NVARCHAR(4000), _ @Inequality_columns NVARCHAR(4000), @index_handlE INT) RETURNS VARCHAR(128) AS BEGIN DECLAR E @IndexName NVARCHAR(MAX) SET @IndexName = ISNULL(@equali ty_columns,@Inequality_columns) SET @IndexName = LTRIM(REPLACE(@IndexName,'[','_')) SET @IndexName = RTRIM(REPLACE(@IndexName,']','_')) SET @IndexName = REPLACE(@IndexName,',','') SET @IndexName = REPLACE(@IndexName,'_ _','_') IF LEN(@IndexName) > 120 BEGIN SET @IndexName = SUBSTRING(@IndexName,0,120) END SET @IndexName = @IndexName + CAST(@index_handlE AS NVARCHAR(15)) RETURN @IndexName END GO -- CREATE FUNCTION vw_Index_MissingIndex CREATE VIEW [dbo].[vw_Index_MissingIndex] AS SELECT '[' + d.name + ']' as DBName, [dbo].[fn_Index_CreateIndexName]_ (mid.equality_columns,mid.Inequality_columns,mid.index_handlE) AS ID, REPLACE(mid.equality_columns,',',' ASC,') AS equality_columns, REPLACE(mid.Inequality_columns,',',' ASC,') AS Inequality_columns, mid.Included_columns, mid.[statement] FROM sys.dm_db_missing_index_details mid INNER JOIN sys.databases d on d.database_id = mid.database_id GO CREATE PROCEDURE [dbo].[usp_Index_MissingIndexCreationStatements] AS DECLARE @IndexCreationPlaceholder_Start AS NVARCHAR(MAX) DECLARE @IndexCreationPlaceholder_End AS NVARCHAR(MAX) -- PREPARE PLACEHOLDER SET @IndexCreationPlaceholder_Start = 'IF NOT EXISTS_ (SELECT * FROM {2}.sys.indexes WHERE [name] = ''IX_{0}'' ) BEGIN CREATE NONCLUSTERED INDEX [IX_{0}] ON {1}' SET @IndexCreationPlaceholder_End = ' 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] END;' + char(13) + char(10) -- STATEMENT CREATION SELECT DBName, CASE WHEN NOT mid.equality_columns IS NULL AND NOT mid.Inequality_columns IS NULL THEN REPLACE(REPLACE(REPLACE(@IndexCreationPlaceholder_Start,'{0}', _ mid.ID),'{1}',mid.[statement]),'{2}',mid.DBName) + ' ( ' + COALESCE(mid.equality_columns,'') + ' ASC,' + COALESCE(mid.Inequality_columns,'') + ' ASC )' + COALESCE('INCLUDE ( ' + mid.Included_columns + ' ) ','') + @IndexCreationPlaceholder_End WHEN mid.equality_columns IS NULL AND NOT mid.Inequality_columns IS NULL THEN REPLACE(REPLACE(REPLACE(@IndexCreationPlaceholder_Start,'{0}', _ mid.ID),'{1}',mid.[statement]),'{2}',mid.DBName) + ' ( ' + COALESCE(mid.Inequality_columns,'') + ' ASC ) ' + COALESCE('INCLUDE ( ' + mid.Included_columns + ' ) ','') + @IndexCreationPlaceholder_End WHEN NOT mid.equality_columns IS NULL AND mid.Inequality_columns IS NULL THEN REPLACE(REPLACE(REPLACE(@IndexCreationPlaceholder_Start,'{0}', _ mid.ID),'{1}',mid.[statement]),'{2}',mid.DBName) + ' ( ' + COALESCE(mid.equality_columns,'') + ' ASC ) ' + COALESCE('INCLUDE ( ' + mid.Included_columns + ' ) ','') + @IndexCreationPlaceholder_End ELSE NULL END AS Index_Creation_Statement, ' DROP INDEX [IX_' + mid.ID + '] ON ' + mid.[statement] _ + + char(13) + char(10) AS Index_Drop_Statement FROM [dbo].[vw_Index_MissingIndex] AS mid GO
以上是“如何使用系統(tǒng)SQL實(shí)體自動(dòng)創(chuàng)建非聚集索引”這篇文章的所有內(nèi)容,感謝各位的閱讀!相信大家都有了一定的了解,希望分享的內(nèi)容對(duì)大家有所幫助,如果還想學(xué)習(xí)更多知識(shí),歡迎關(guān)注億速云行業(yè)資訊頻道!
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