提高大型表上的 SQL Server 查询性能 [英] Improve SQL Server query performance on large tables
本文介绍了提高大型表上的 SQL Server 查询性能的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我有一个相对较大的表(目前有 200 万条记录)，想知道是否可以提高临时查询的性能.ad-hoc 这个词在这里很关键.添加索引不是一个选项(最常查询的列上已经有索引).
I have a relatively large table (currently 2 million records) and would like to know if it's possible to improve performance for ad-hoc queries. The word ad-hoc being key here. Adding indexs is not an option (there are already indexs on the columns which are queried most commonly).
运行一个简单的查询来返回最近更新的 100 条记录:
Running a simple query to return the 100 most recently updated records:
select top 100 * from ER101_ACCT_ORDER_DTL order by er101_upd_date_iso desc
需要几分钟.请参阅下面的执行计划:
Takes several minutes. See execution plan below:
表扫描的其他详细信息:
Additional detail from the table scan:
SQL Server Execution Times:
CPU time = 3945 ms, elapsed time = 148524 ms.
运行 sql server 2008 r2 x64 的服务器非常强大(来自内存 48GB ram，24 核处理器).
The server is pretty powerful (from memory 48GB ram, 24 core processor) running sql server 2008 r2 x64.
更新
我发现这段代码可以创建一个包含 1,000,000 条记录的表.我想我可以然后在几个不同的服务器上运行 SELECT TOP 100 * FROM testEnvironment ORDER BY mailAddress DESC 来确定我的磁盘访问速度在服务器上是否很差.
I found this code to create a table with 1,000,000 records. I thought i could then run SELECT TOP 100 * FROM testEnvironment ORDER BY mailAddress DESC on a few different servers to find out if my disk access speeds were poor on the server.
WITH t1(N) AS (SELECT 1 UNION ALL SELECT 1),
t2(N) AS (SELECT 1 FROM t1 x, t1 y),
t3(N) AS (SELECT 1 FROM t2 x, t2 y),
Tally(N) AS (SELECT TOP 98 ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) FROM t3 x, t3 y),
Tally2(N) AS (SELECT TOP 5 ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) FROM t3 x, t3 y),
Combinations(N) AS (SELECT DISTINCT LTRIM(RTRIM(RTRIM(SUBSTRING(poss,a.N,2)) + SUBSTRING(vowels,b.N,1)))
FROM Tally a
CROSS JOIN Tally2 b
CROSS APPLY (SELECT 'B C D F G H J K L M N P R S T V W Z SCSKKNSNSPSTBLCLFLGLPLSLBRCRDRFRGRPRTRVRSHSMGHCHPHRHWHBWCWSWTW') d(poss)
CROSS APPLY (SELECT 'AEIOU') e(vowels))
SELECT IDENTITY(INT,1,1) AS ID, a.N + b.N AS N
INTO #testNames
FROM Combinations a
CROSS JOIN Combinations b;
SELECT IDENTITY(INT,1,1) AS ID, firstName, secondName
INTO #testNames2
FROM (SELECT firstName, secondName
FROM (SELECT TOP 1000 --1000 * 1000 = 1,000,000 rows
N AS firstName
FROM #testNames
ORDER BY NEWID()) a
CROSS JOIN (SELECT TOP 1000 --1000 * 1000 = 1,000,000 rows
N AS secondName
FROM #testNames
ORDER BY NEWID()) b) innerQ;
SELECT firstName, secondName,
firstName + '.' + secondName + '@fake.com' AS eMail,
CAST((ABS(CHECKSUM(NEWID())) % 250) + 1 AS VARCHAR(3)) + ' ' AS mailAddress,
(ABS(CHECKSUM(NEWID())) % 152100) + 1 AS jID,
IDENTITY(INT,1,1) AS ID
INTO #testNames3
FROM #testNames2
SELECT IDENTITY(INT,1,1) AS ID, firstName, secondName, eMail,
mailAddress + b.N + b.N AS mailAddress
INTO testEnvironment
FROM #testNames3 a
INNER JOIN #testNames b ON a.jID = b.ID;
--CLEAN UP USELESS TABLES
DROP TABLE #testNames;
DROP TABLE #testNames2;
DROP TABLE #testNames3;
但是在三个测试服务器上，查询几乎是立即运行的.谁能解释一下?
But on the three test servers the query ran almost instantaneously. Can anyone explain this?
更新 2
感谢您的评论 - 请让他们继续发表...他们让我尝试将主键索引从非聚集更改为聚集，结果相当有趣(和意外?).
Thank you for the comments- please keep them coming... they led me to try changing the primary key index from non-clustered to clustered with rather interesting (and unexpected?) results.
非集群:
SQL Server Execution Times:
CPU time = 3634 ms, elapsed time = 154179 ms.
集群:
SQL Server Execution Times:
CPU time = 2650 ms, elapsed time = 52177 ms.
这怎么可能?er101_upd_date_iso 列没有索引如何使用聚集索引扫描?
How is this possible? Without an index on the er101_upd_date_iso column how can a clustered index scan be used?
更新 3
根据要求 - 这是创建表脚本:
As requested- this is the create table script:
CREATE TABLE [dbo].[ER101_ACCT_ORDER_DTL](
[ER101_ORG_CODE] [varchar](2) NOT NULL,
[ER101_ORD_NBR] [int] NOT NULL,
[ER101_ORD_LINE] [int] NOT NULL,
[ER101_EVT_ID] [int] NULL,
[ER101_FUNC_ID] [int] NULL,
[ER101_STATUS_CDE] [varchar](2) NULL,
[ER101_SETUP_ID] [varchar](8) NULL,
[ER101_DEPT] [varchar](6) NULL,
[ER101_ORD_TYPE] [varchar](2) NULL,
[ER101_STATUS] [char](1) NULL,
[ER101_PRT_STS] [char](1) NULL,
[ER101_STS_AT_PRT] [char](1) NULL,
[ER101_CHG_COMMENT] [varchar](255) NULL,
[ER101_ENT_DATE_ISO] [datetime] NULL,
[ER101_ENT_USER_ID] [varchar](10) NULL,
[ER101_UPD_DATE_ISO] [datetime] NULL,
[ER101_UPD_USER_ID] [varchar](10) NULL,
[ER101_LIN_NBR] [int] NULL,
[ER101_PHASE] [char](1) NULL,
[ER101_RES_CLASS] [char](1) NULL,
[ER101_NEW_RES_TYPE] [varchar](6) NULL,
[ER101_RES_CODE] [varchar](12) NULL,
[ER101_RES_QTY] [numeric](11, 2) NULL,
[ER101_UNIT_CHRG] [numeric](13, 4) NULL,
[ER101_UNIT_COST] [numeric](13, 4) NULL,
[ER101_EXT_COST] [numeric](11, 2) NULL,
[ER101_EXT_CHRG] [numeric](11, 2) NULL,
[ER101_UOM] [varchar](3) NULL,
[ER101_MIN_CHRG] [numeric](11, 2) NULL,
[ER101_PER_UOM] [varchar](3) NULL,
[ER101_MAX_CHRG] [numeric](11, 2) NULL,
[ER101_BILLABLE] [char](1) NULL,
[ER101_OVERRIDE_FLAG] [char](1) NULL,
[ER101_RES_TEXT_YN] [char](1) NULL,
[ER101_DB_CR_FLAG] [char](1) NULL,
[ER101_INTERNAL] [char](1) NULL,
[ER101_REF_FIELD] [varchar](255) NULL,
[ER101_SERIAL_NBR] [varchar](50) NULL,
[ER101_RES_PER_UNITS] [int] NULL,
[ER101_SETUP_BILLABLE] [char](1) NULL,
[ER101_START_DATE_ISO] [datetime] NULL,
[ER101_END_DATE_ISO] [datetime] NULL,
[ER101_START_TIME_ISO] [datetime] NULL,
[ER101_END_TIME_ISO] [datetime] NULL,
[ER101_COMPL_STS] [char](1) NULL,
[ER101_CANCEL_DATE_ISO] [datetime] NULL,
[ER101_BLOCK_CODE] [varchar](6) NULL,
[ER101_PROP_CODE] [varchar](8) NULL,
[ER101_RM_TYPE] [varchar](12) NULL,
[ER101_WO_COMPL_DATE] [datetime] NULL,
[ER101_WO_BATCH_ID] [varchar](10) NULL,
[ER101_WO_SCHED_DATE_ISO] [datetime] NULL,
[ER101_GL_REF_TRANS] [char](1) NULL,
[ER101_GL_COS_TRANS] [char](1) NULL,
[ER101_INVOICE_NBR] [int] NULL,
[ER101_RES_CLOSED] [char](1) NULL,
[ER101_LEAD_DAYS] [int] NULL,
[ER101_LEAD_HHMM] [int] NULL,
[ER101_STRIKE_DAYS] [int] NULL,
[ER101_STRIKE_HHMM] [int] NULL,
[ER101_LEAD_FLAG] [char](1) NULL,
[ER101_STRIKE_FLAG] [char](1) NULL,
[ER101_RANGE_FLAG] [char](1) NULL,
[ER101_REQ_LEAD_STDATE] [datetime] NULL,
[ER101_REQ_LEAD_ENDATE] [datetime] NULL,
[ER101_REQ_STRK_STDATE] [datetime] NULL,
[ER101_REQ_STRK_ENDATE] [datetime] NULL,
[ER101_LEAD_STDATE] [datetime] NULL,
[ER101_LEAD_ENDATE] [datetime] NULL,
[ER101_STRK_STDATE] [datetime] NULL,
[ER101_STRK_ENDATE] [datetime] NULL,
[ER101_DEL_MARK] [char](1) NULL,
[ER101_USER_FLD1_02X] [varchar](2) NULL,
[ER101_USER_FLD1_04X] [varchar](4) NULL,
[ER101_USER_FLD1_06X] [varchar](6) NULL,
[ER101_USER_NBR_060P] [int] NULL,
[ER101_USER_NBR_092P] [numeric](9, 2) NULL,
[ER101_PR_LIST_DTL] [numeric](11, 2) NULL,
[ER101_EXT_ACCT_CODE] [varchar](8) NULL,
[ER101_AO_STS_1] [char](1) NULL,
[ER101_PLAN_PHASE] [char](1) NULL,
[ER101_PLAN_SEQ] [int] NULL,
[ER101_ACT_PHASE] [char](1) NULL,
[ER101_ACT_SEQ] [int] NULL,
[ER101_REV_PHASE] [char](1) NULL,
[ER101_REV_SEQ] [int] NULL,
[ER101_FORE_PHASE] [char](1) NULL,
[ER101_FORE_SEQ] [int] NULL,
[ER101_EXTRA1_PHASE] [char](1) NULL,
[ER101_EXTRA1_SEQ] [int] NULL,
[ER101_EXTRA2_PHASE] [char](1) NULL,
[ER101_EXTRA2_SEQ] [int] NULL,
[ER101_SETUP_MSTR_SEQ] [int] NULL,
[ER101_SETUP_ALTERED] [char](1) NULL,
[ER101_RES_LOCKED] [char](1) NULL,
[ER101_PRICE_LIST] [varchar](10) NULL,
[ER101_SO_SEARCH] [varchar](9) NULL,
[ER101_SSB_NBR] [int] NULL,
[ER101_MIN_QTY] [numeric](11, 2) NULL,
[ER101_MAX_QTY] [numeric](11, 2) NULL,
[ER101_START_SIGN] [char](1) NULL,
[ER101_END_SIGN] [char](1) NULL,
[ER101_START_DAYS] [int] NULL,
[ER101_END_DAYS] [int] NULL,
[ER101_TEMPLATE] [char](1) NULL,
[ER101_TIME_OFFSET] [char](1) NULL,
[ER101_ASSIGN_CODE] [varchar](10) NULL,
[ER101_FC_UNIT_CHRG] [numeric](13, 4) NULL,
[ER101_FC_EXT_CHRG] [numeric](11, 2) NULL,
[ER101_CURRENCY] [varchar](3) NULL,
[ER101_FC_RATE] [numeric](12, 5) NULL,
[ER101_FC_DATE] [datetime] NULL,
[ER101_FC_MIN_CHRG] [numeric](11, 2) NULL,
[ER101_FC_MAX_CHRG] [numeric](11, 2) NULL,
[ER101_FC_FOREIGN] [numeric](12, 5) NULL,
[ER101_STAT_ORD_NBR] [int] NULL,
[ER101_STAT_ORD_LINE] [int] NULL,
[ER101_DESC] [varchar](255) NULL
) ON [PRIMARY]
SET ANSI_PADDING OFF
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_PRT_SEQ_1] [varchar](12) NULL
SET ANSI_PADDING ON
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_PRT_SEQ_2] [varchar](120) NULL
SET ANSI_PADDING OFF
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_TAX_BASIS] [char](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_RES_CATEGORY] [char](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_DECIMALS] [char](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_TAX_SEQ] [varchar](7) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_MANUAL] [char](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_TR_LC_RATE] [numeric](12, 5) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_TR_FC_RATE] [numeric](12, 5) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_TR_PL_RATE] [numeric](12, 5) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_TR_DIFF] [char](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_TR_UNIT_CHRG] [numeric](13, 4) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_TR_EXT_CHRG] [numeric](13, 4) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_TR_MIN_CHRG] [numeric](13, 4) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_TR_MAX_CHRG] [numeric](13, 4) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_PL_UNIT_CHRG] [numeric](13, 4) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_PL_EXT_CHRG] [numeric](13, 2) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_PL_MIN_CHRG] [numeric](13, 2) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_PL_MAX_CHRG] [numeric](13, 2) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_TAX_RATE_TYPE] [char](1) NULL
SET ANSI_PADDING ON
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_ORDER_FORM] [varchar](2) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_FACTOR] [int] NULL
SET ANSI_PADDING OFF
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_MGMT_RPT_CODE] [varchar](6) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_ROUND_CHRG] [varchar](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_WHOLE_QTY] [varchar](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_SET_QTY] [numeric](15, 4) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_SET_UNITS] [numeric](15, 4) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_SET_ROUNDING] [varchar](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_SET_SUB] [varchar](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_TIME_QTY] [numeric](13, 4) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_GL_DISTR_PCT] [numeric](7, 4) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_REG_SEQ] [int] NULL
SET ANSI_PADDING ON
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_ALT_DESC] [varchar](255) NULL
SET ANSI_PADDING OFF
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_REG_ACCT] [varchar](8) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_DAILY] [varchar](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_AVG_UNIT_CHRG] [varchar](1) NULL
SET ANSI_PADDING ON
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_ALT_DESC2] [varchar](255) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_CONTRACT_SEQ] [int] NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_ORIG_RATE] [numeric](13, 4) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_DISC_PCT] [decimal](17, 10) NULL
SET ANSI_PADDING OFF
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_DTL_EXIST] [varchar](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_ORDERED_ONLY] [varchar](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_SHOW_STDATE] [varchar](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_SHOW_STTIME] [varchar](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_SHOW_ENDATE] [varchar](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_SHOW_ENTIME] [varchar](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_SHOW_RATE] [varchar](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_SHOW_UNITS] [varchar](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_BASE_RATE] [numeric](13, 4) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_COMMIT_QTY] [numeric](11, 2) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_MM_QTY_USED] [varchar](2) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_MM_CHRG_USED] [varchar](2) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_ITEM_TEXT_1] [varchar](50) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_ITEM_NBR_1] [numeric](13, 3) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_ITEM_NBR_2] [numeric](13, 3) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_ITEM_NBR_3] [numeric](13, 3) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_PL_BASE_RATE] [numeric](13, 4) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_REV_DIST] [varchar](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_COVER] [int] NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_RATE_TYPE] [varchar](2) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_USE_SEASONAL] [varchar](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_TAX_EI] [varchar](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_TAXES] [numeric](13, 2) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_FC_TAXES] [numeric](13, 2) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_PL_TAXES] [numeric](13, 2) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_FC_QTY] [numeric](13, 2) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_LEAD_HRS] [numeric](6, 2) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_STRIKE_HRS] [numeric](6, 2) NULL
SET ANSI_PADDING ON
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_CANCEL_USER_ID] [varchar](10) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_ST_OFFSET_HRS] [numeric](7, 2) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_EN_OFFSET_HRS] [numeric](7, 2) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_MEMO_FLAG] [varchar](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_MEMO_EXT_CHRG] [numeric](13, 4) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_MEMO_EXT_CHRG_PL] [numeric](13, 4) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_MEMO_EXT_CHRG_TR] [numeric](13, 4) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_MEMO_EXT_CHRG_FC] [numeric](13, 4) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_TIME_QTY_EDIT] [varchar](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_SURCHARGE_PCT] [decimal](17, 10) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_INCL_EXT_CHRG] [numeric](13, 4) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_INCL_EXT_CHRG_FC] [numeric](13, 4) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_CARRIER] [varchar](6) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_SETUP_ID2] [varchar](8) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_SHIPPABLE] [varchar](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_CHARGEABLE] [varchar](2) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_ITEM_NBR_ALLOW] [varchar](2) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_ITEM_NBR_START] [int] NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_ITEM_NBR_END] [int] NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_ITEM_SUPPLIER] [varchar](8) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_TRACK_ID] [varchar](40) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_REF_INV_NBR] [int] NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_NEW_ITEM_STS] [varchar](2) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_MSTR_REG_ACCT_CODE] [varchar](8) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_ALT_DESC3] [varchar](255) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_ALT_DESC4] [varchar](255) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_ALT_DESC5] [varchar](255) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_SETUP_ROLLUP] [varchar](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_MM_COST_USED] [varchar](2) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_AUTO_SHIP_RCD] [varchar](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_ITEM_FIXED] [varchar](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_ITEM_EST_TBD] [varchar](3) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_ROLLUP_PL_UNIT_CHRG] [numeric](13, 4) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_ROLLUP_PL_EXT_CHRG] [numeric](13, 2) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_GL_ORD_REV_TRANS] [varchar](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_DISCOUNT_FLAG] [varchar](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_SETUP_RES_TYPE] [varchar](6) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_SETUP_RES_CODE] [varchar](12) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_PERS_SCHED_FLAG] [varchar](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_PRINT_STAMP] [datetime] NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_SHOW_EXT_CHRG] [varchar](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_PRINT_SEQ_NBR] [int] NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_PAY_LOCATION] [varchar](3) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_MAX_RM_NIGHTS] [int] NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_USE_TIER_COST] [varchar](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_UNITS_SCHEME_CODE] [varchar](6) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_ROUND_TIME] [varchar](2) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_LEVEL] [int] NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_SETUP_PARENT_ORD_LINE] [int] NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_BADGE_PRT_STS] [varchar](1) NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_EVT_PROMO_SEQ] [int] NULL
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD [ER101_REG_TYPE] [varchar](12) NULL
/****** Object: Index [PK__ER101_ACCT_ORDER] Script Date: 04/15/2012 20:24:37 ******/
ALTER TABLE [dbo].[ER101_ACCT_ORDER_DTL] ADD CONSTRAINT [PK__ER101_ACCT_ORDER] PRIMARY KEY CLUSTERED
(
[ER101_ORD_NBR] ASC,
[ER101_ORD_LINE] ASC,
[ER101_ORG_CODE] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON, FILLFACTOR = 50) ON [PRIMARY]
表大小为 2.8 GB，索引大小为 3.9 GB.
The table is 2.8 GB in size with index size standing at 3.9 GB.
推荐答案
简单回答:NO.您无法帮助对 238 列的表进行临时查询，其中聚集索引的填充因子为 50%.
Simple Answer: NO. You cannot help ad hoc queries on a 238 column table with a 50% Fill Factor on the Clustered Index.
详细回答:
正如我在关于此主题的其他答案中所述，索引设计既是艺术又是科学，需要考虑的因素太多，几乎没有硬性规则.您需要考虑:DML 操作与 SELECT 的数量、磁盘子系统、表上的其他索引/触发器、表内数据的分布、使用 SARGable WHERE 条件的查询，以及其他一些我什至记不起来的事情现在.
As I have stated in other answers on this topic, Index design is both Art and Science and there are so many factors to consider that there are few, if any, hard and fast rules. You need to consider: the volume of DML operations vs SELECTs, disk subsystem, other indexes / triggers on the table, distribution of data within the table, are queries using SARGable WHERE conditions, and several other things that I can't even remember right now.
我可以说，如果不了解表本身、其索引、触发器等，就无法对有关此主题的问题提供任何帮助.现在您已经发布了表定义(仍在等待索引但表定义单独指出 99% 的问题)我可以提供一些建议.
I can say that no help can be given for questions on this topic without an understanding of the Table itself, its indexes, triggers, etc. Now that you have posted the table definition (still waiting on the Indexes but the Table definition alone points to 99% of the issue) I can offer some suggestions.
首先，如果表定义是准确的(238 列，50% 填充因子)，那么您几乎可以忽略此处的其余答案/建议；-).很抱歉在这里不那么政治化，但说真的，这是一场不知道具体细节的疯狂追逐.现在我们看到了表定义，即使测试查询(更新 #1)运行得如此之快，为什么一个简单的查询会花费这么长时间就变得非常清楚了.
First, if the table definition is accurate (238 columns, 50% Fill Factor) then you can pretty much ignore the rest of the answers / advice here ;-). Sorry to be less-than-political here, but seriously, it's a wild goose chase without knowing the specifics. And now that we see the table definition it becomes quite a bit clearer as to why a simple query would take so long, even when the test queries (Update #1) ran so quickly.
这里(以及在许多性能不佳的情况下)的主要问题是糟糕的数据建模.238列不禁止，就像999个索引不禁止一样，但通常也不是很明智.
The main problem here (and in many poor-performance situations) is bad data modeling. 238 columns is not prohibited just like having 999 indexes is not prohibited, but it is also generally not very wise.
建议:
- 首先，这张桌子确实需要改造.如果这是一个数据仓库表，那么也许可以，但如果不是，那么这些字段真的需要分解成几个表，这些表都可以具有相同的 PK.您将拥有一个主记录表，而子表只是基于共同关联属性的相关信息，这些表的 PK 与主表的 PK 相同，因此也与主表的 FK 相同.主表和所有子表之间将存在一对一的关系.
ANSI_PADDING OFF的使用令人不安，更不用说由于随着时间的推移添加了各种列而导致的表内不一致.不确定您现在是否可以解决该问题，但理想情况下，您将始终具有ANSI_PADDING ON，或者至少在所有ALTER TABLE语句中具有相同的设置.- 考虑创建 2 个额外的文件组:表和索引.最好不要把你的东西放在
PRIMARY中，因为这是 SQL SERVER 存储关于你的对象的所有数据和元数据的地方.您在[Tables]上创建表和聚集索引(因为这是表的数据)，并在[Indexes] 上创建所有非聚集索引 - 将填充因子从 50% 增加.这个低数字很可能是您的索引空间大于数据空间的原因.执行索引重建将重新创建最多 4k(总页面大小为 8k 页面大小)的数据页面用于您的数据，以便您的表分布在一个广阔的区域.
- 如果大多数或所有查询在
WHERE条件中都有ER101_ORG_CODE"，则考虑将其移至聚集索引的前导列.假设它比ER101_ORD_NBR"更常用.如果更频繁地使用ER101_ORD_NBR"，则保留它.看起来，假设字段名称意味着OrganizationCode"和OrderNumber"，那么OrgCode"是一个更好的分组，其中可能包含多个OrderNumbers". - 次要问题，但如果ER101_ORG_CODE"始终为 2 个字符，则使用
CHAR(2)而不是VARCHAR(2)因为它会在跟踪可变宽度大小并加起来超过数百万行的行标题. - 正如这里的其他人所提到的，使用
SELECT *会影响性能.不仅因为它需要 SQL Server 返回所有列，因此无论您的其他索引如何，都更有可能进行聚集索引扫描，而且还需要 SQL Server 花费时间转到表定义并转换*到所有列名中.在SELECT列表中指定所有 238 个列名称应该稍微更快，尽管这无助于扫描问题.但是您真的需要同时使用所有 238 列吗?
- First, this table really needs to be remodeled. If this is a data warehouse table then maybe, but if not then these fields really need to be broken up into several tables which can all have the same PK. You would have a master record table and the child tables are just dependent info based on commonly associated attributes and the PK of those tables is the same as the PK of the master table and hence also FK to the master table. There will be a 1-to-1 relationship between master and all child tables.
- The use of
ANSI_PADDING OFFis disturbing, not to mention inconsistent within the table due to the various column additions over time. Not sure if you can fix that now, but ideally you would always haveANSI_PADDING ON, or at the very least have the same setting across allALTER TABLEstatements. - Consider creating 2 additional File Groups: Tables and Indexes. It is best not to put your stuff in
PRIMARYas that is where SQL SERVER stores all of its data and meta-data about your objects. You create your Table and Clustered Index (as that is the data for the table) on[Tables]and all Non-Clustered indexes on[Indexes] - Increase the Fill Factor from 50%. This low number is likely why your index space is larger than your data space. Doing an Index Rebuild will recreate the data pages with a max of 4k (out of the total 8k page size) used for your data so your table is spread out over a wide area.
- If most or all queries have "ER101_ORG_CODE" in the
WHEREcondition, then consider moving that to the leading column of the clustered index. Assuming that it is used more often than "ER101_ORD_NBR". If "ER101_ORD_NBR" is used more often then keep it. It just seems, assuming that the field names mean "OrganizationCode" and "OrderNumber", that "OrgCode" is a better grouping that might have multiple "OrderNumbers" within it. - Minor point, but if "ER101_ORG_CODE" is always 2 characters, then use
CHAR(2)instead ofVARCHAR(2)as it will save a byte in the row header which tracks variable width sizes and adds up over millions of rows. - As others here have mentioned, using
SELECT *will hurt performance. Not only due to it requiring SQL Server to return all columns and hence be more likely to do a Clustered Index Scan regardless of your other indexes, but it also takes SQL Server time to go to the table definition and translate*into all of the column names. It should be slightly faster to specify all 238 column names in theSELECTlist though that won't help the Scan issue. But do you ever really need all 238 columns at the same time anyway?
祝你好运！
更新
为了如何提高临时查询的大表的性能"问题的完整性，应该注意的是，虽然它对这种特定情况没有帮助，但如果有人使用 SQL Server 2012(或更新的那个时候到了)并且如果表没有被更新，那么使用列存储索引是一种选择.有关该新功能的更多详细信息，请查看此处:http://msdn.microsoft.com/en-us/library/gg492088.aspx(我相信这些是从 SQL Server 2014 开始可更新的).
UPDATE
For the sake of completeness to the question "how to improve performance on a large table for ad-hoc queries", it should be noted that while it will not help for this specific case, IF someone is using SQL Server 2012 (or newer when that time comes) and IF the table is not being updated, then using Columnstore Indexes is an option. For more details on that new feature, look here:
http://msdn.microsoft.com/en-us/library/gg492088.aspx (I believe these were made to be updateable starting in SQL Server 2014).
更新 2
其他注意事项是:
UPDATE 2
Additional considerations are:
- 对聚集索引启用压缩.此选项在 SQL Server 2008 中可用，但仅作为企业版功能.但是，从 SQL Server 2016 SP1 开始，数据压缩可用所有版本！请参阅 MSDN 页面了解数据压缩 有关行和页面压缩的详细信息.
- 如果您不能使用数据压缩，或者它不会为特定表提供太多好处，那么如果您有一个固定长度类型的列 (
INT,BIGINT、TINYINT、SMALLINT、CHAR、NCHAR、BINARY、DATETIME、SMALLDATETIME、MONEY等)以及超过 50% 的行是NULL，然后考虑启用在 SQL Server 2008 中可用的SPARSE选项.请参阅 MSDN 页面以了解 使用稀疏列 了解详情.
- Enable compression on the Clustered Index. This option became available in SQL Server 2008, but as an Enterprise Edition-only feature. However, as of SQL Server 2016 SP1, Data Compression was made available in all editions! Please see the MSDN page for Data Compression for details on Row and Page Compression.
- If you cannot use Data Compression, or if it won't provide much benefit for a particular table, then IF you have a column of a fixed-length type (
INT,BIGINT,TINYINT,SMALLINT,CHAR,NCHAR,BINARY,DATETIME,SMALLDATETIME,MONEY, etc) and well over 50% of the rows areNULL, then consider enabling theSPARSEoption which became available in SQL Server 2008. Please see the MSDN page for Use Sparse Columns for details.
这篇关于提高大型表上的 SQL Server 查询性能的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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