数据库维护每天重建索引

Question

我的数据库大约是 2.5TB。每天运行重建索引是一个好习惯吗？

我们每天删除大约 20 GB 的数据 & 同时我们删除分区 & 我们将添加新分区。运行重建索引需要 8 小时，有时需要 24 小时。在此期间，日志文件增加到 300 GB。

我们需要将数据库碎片的每日报告发送给客户。看到 99% 或 98% 的人都会害怕。请建议。

表大小为 70GB，对于此表碎片级别，每天将是 99%。不知道是什么让客户要求每日报告碎片级别，但他每天都需要它。

Answer 1

首先，您应该考虑page_count索引的 。如果page_count小于 1000（或您决定的任何值），那么您应该忽略 index。

我们有一个维护脚本来分析page_count索引的碎片并遵循以下准则：-

• 小于10%的逻辑碎片，什么都不做
• 10% 到 30% 的逻辑碎片，重新组织它（使用ALTER INDEX … REORGANIZE）
• 超过 30% 的逻辑碎片，重建它（使用ALTER INDEX … REBUILD）（ONLINE= ON对于企业版）

这是找出您目前所在位置的入门：-

SELECT dbtables.[name] AS 'Table'
    ,dbindexes.[name] AS 'Index'
    ,indexstats.avg_fragmentation_in_percent
    ,CASE 
        WHEN indexstats.avg_fragmentation_in_percent < 10
            THEN 'NOTHING'
        WHEN indexstats.avg_fragmentation_in_percent >= 10
            AND indexstats.avg_fragmentation_in_percent < 30
            THEN 'REORGANIZE'
        WHEN indexstats.avg_fragmentation_in_percent >= 30
            THEN 'REBUILD'
        END
    ,indexstats.page_count
FROM sys.dm_db_index_physical_stats(DB_ID(), NULL, NULL, NULL, NULL) AS indexstats
INNER JOIN sys.tables dbtables ON dbtables.[object_id] = indexstats.[object_id]
INNER JOIN sys.schemas dbschemas ON dbtables.[schema_id] = dbschemas.[schema_id]
INNER JOIN sys.indexes AS dbindexes ON dbindexes.[object_id] = indexstats.[object_id]
    AND indexstats.index_id = dbindexes.index_id
WHERE indexstats.database_id = DB_ID()
    AND page_count > 1000
    AND dbindexes.NAME IS NOT NULL
ORDER BY indexstats.avg_fragmentation_in_percent DESC

这一切都取决于您的要求。如果您每周只重建一次，对性能有何影响？你能在重建后每周发送一次报告吗？我会在测试环境（如果可能）中对性能进行基准测试，如果它不会降级太多，则每周只执行一次索引维护。

代理工作可能是这样的：-

DECLARE @Indexes AS TABLE (
    ID INT IDENTITY(1, 1) NOT NULL
    ,TableNm VARCHAR(500) NOT NULL
    ,IndexNm VARCHAR(500) NOT NULL
    ,FragPerc DECIMAL(16, 3) NOT NULL
    ,RecAction VARCHAR(50) NOT NULL
    ,PageCount INT NOT NULL
    )
INSERT INTO @Indexes
SELECT dbtables.[name] AS 'Table'
    ,dbindexes.[name] AS 'Index'
    ,indexstats.avg_fragmentation_in_percent
    ,CASE 
        WHEN indexstats.avg_fragmentation_in_percent < 10 --change all levels to your requirement
            THEN 'NOTHING'
        WHEN indexstats.avg_fragmentation_in_percent >= 10
            AND indexstats.avg_fragmentation_in_percent < 30
            THEN 'REORGANIZE'
        WHEN indexstats.avg_fragmentation_in_percent >= 30
            THEN 'REBUILD'
        END
    ,indexstats.page_count
FROM sys.dm_db_index_physical_stats(DB_ID(), NULL, NULL, NULL, NULL) AS indexstats
INNER JOIN sys.tables dbtables ON dbtables.[object_id] = indexstats.[object_id]
INNER JOIN sys.schemas dbschemas ON dbtables.[schema_id] = dbschemas.[schema_id]
INNER JOIN sys.indexes AS dbindexes ON dbindexes.[object_id] = indexstats.[object_id]
    AND indexstats.index_id = dbindexes.index_id
WHERE indexstats.database_id = DB_ID()
    AND page_count > 1000
    AND dbindexes.NAME IS NOT NULL
ORDER BY indexstats.avg_fragmentation_in_percent DESC

DELETE FROM @Indexes WHERE RecAction = 'NOTHING'

DECLARE @sql AS VARCHAR(MAX)
DECLARE @whilecount AS INT = 1
DECLARE @rowcount AS INT = (
        SELECT MAX(ID)
        FROM @Indexes
        )
DECLARE @IndexNm AS VARCHAR(500)
DECLARE @TableNm AS VARCHAR(500)
DECLARE @RecAction AS VARCHAR(50)

WHILE @whilecount <= @rowcount
BEGIN
    SET @IndexNm = (
            SELECT IndexNm
            FROM @Indexes
            WHERE ID = @whilecount
            )
    SET @TableNm = (
            SELECT TableNm
            FROM @Indexes
            WHERE ID = @whilecount
            )
    SET @RecAction = (
            SELECT RecAction
            FROM @Indexes
            WHERE ID = @whilecount
            )

    IF @RecAction = 'REBUILD'
    BEGIN
        SET @sql = 'ALTER INDEX [' + @IndexNm + '] ON [' + @TableNm + '] REBUILD WITH (FILLFACTOR = 98, ONLINE = ON);' --change depending on SQL version
    END
    ELSE IF @RecAction = 'REORGANIZE'
    BEGIN
        SET @sql = 'ALTER INDEX [' + @IndexNm + '] ON [' + @TableNm + '] REORGANIZE;'
    END

    EXECUTE (@sql);

    SET @whilecount += 1
END