Вопрос по sql-server-2008, sql-server, sql – Повышение производительности запросов к SQL Server для больших таблиц

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У меня относительно большая таблица (в настоящее время 2 миллиона записей), и я хотел бы знать, возможно ли повысить производительность для специальных запросов. Словоad-hoc быть ключевым здесь. Добавление индексов не вариант (уже есть индексы по столбцам, которые запрашиваются чаще всего).

Выполнение простого запроса для возврата 100 последних обновленных записей:

select top 100 * from ER101_ACCT_ORDER_DTL order by er101_upd_date_iso desc

Занимает несколько минут. Смотрите план выполнения ниже:

enter image description here

Дополнительные детали из таблицы сканирования:

enter image description here

SQL Server Execution Times:
  CPU time = 3945 ms,  elapsed time = 148524 ms.

Сервер довольно мощный (из оперативной памяти 48 ГБ, 24-ядерный процессор) под управлением SQL Server 2008 R2 x64.

Update

Я нашел этот код для создания таблицы с 1 000 000 записей. Я думал, что мог тогда бежатьSELECT TOP 100 * FROM testEnvironment ORDER BY mailAddress DESC на нескольких разных серверах, чтобы узнать, были ли у меня низкие скорости доступа к диску на сервере.

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;

Но на трех тестовых серверах запрос выполнялся практически мгновенно. Кто-нибудь может объяснить это?

enter image description here

Update 2

Спасибо за комментарии - просьба держать их в курсе ... они заставили меня попробовать изменить индекс первичного ключа с некластеризованного на кластерный с довольно интересными (и неожиданными?) Результатами.

Некластерированных:

enter image description here

SQL Server Execution Times:
  CPU time = 3634 ms,  elapsed time = 154179 ms.

Кластерный:

enter image description here

SQL Server Execution Times:
  CPU time = 2650 ms,  elapsed time = 52177 ms.

Как это возможно? Без индекса в столбце er101_upd_date_iso как можно использовать сканирование кластерного индекса?

Update 3

По запросу - это скрипт создания таблицы:

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]

Размер таблицы составляет 2,8 ГБ, а размер индекса равен 3,9 ГБ.

Table Scan указывает наheap (без кластерного индекса) - поэтому первым шагом было бы добавитьgood, speedy кластерный индекс для вашей таблицы. Вторым этапом может быть выяснение, является ли некластерный индексer101_upd_date_iso поможет (и не вызовет других недостатков производительности) marc_s
Error: User Rate Limit Exceededer101_upd_date_iso столбец, вы также можете избавиться от & quot; Сортировать & quot; операция в вашем плане выполнения и ускорить вещи еще больше marc_s
Есть небольшие подсказки, когда вы наводите курсор мыши на элемент плана. Они показывают приблизительную стоимость ввода-вывода и процессора. Сначала я позабочусь о стоимости ввода / вывода. Grzegorz Gierlik
Error: User Rate Limit Exceeded Lee Tickett
Error: User Rate Limit Exceeded Solomon Rutzky

Ваш Ответ

9   ответов
2

Error: User Rate Limit Exceededselect top 100 * from ER101_ACCT_ORDER_DTL Lee Tickett
12

table scando not have an indexer101_upd_date_iso

there are already indexs on the columns which are queried most commonly

.

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Error: User Rate Limit Exceeded Lee Tickett
Error: User Rate Limit Exceededer101_upd_date_isoError: User Rate Limit Exceeded
Error: User Rate Limit ExceededoptimizeError: User Rate Limit Exceeded Lee Tickett
49

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 OFF is 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 have ANSI_PADDING ON, or at the very least have the same setting across all ALTER TABLE statements. Consider creating 2 additional File Groups: Tables and Indexes. It is best not to put your stuff in PRIMARY as 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 WHERE condition, 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 of VARCHAR(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 the SELECT list though that won't help the Scan issue. But do you ever really need all 238 columns at the same time anyway?

UPDATE

UPDATE 2

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 are NULL, then consider enabling the SPARSE option which became available in SQL Server 2008. Please see the MSDN page for Use Sparse Columns for details.
2

n how can a clustered index scan be used?

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Error: User Rate Limit ExceededError: User Rate Limit Exceeded

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Error: User Rate Limit Exceeded Lee Tickett
Error: User Rate Limit Exceeded
Error: User Rate Limit Exceeded Lee Tickett
1

-- From Glen Barry
-- Clear Wait Stats (consider clearing and running wait stats query again after a few minutes)
-- DBCC SQLPERF('sys.dm_os_wait_stats', CLEAR);

-- Check Task Counts to get an initial idea what the problem might be

-- Avg Current Tasks Count, Avg Runnable Tasks Count, Avg Pending Disk IO Count across all schedulers
-- Run several times in quick succession
SELECT AVG(current_tasks_count) AS [Avg Task Count], 
       AVG(runnable_tasks_count) AS [Avg Runnable Task Count],
       AVG(pending_disk_io_count) AS [Avg Pending DiskIO Count]
FROM sys.dm_os_schedulers WITH (NOLOCK)
WHERE scheduler_id < 255 OPTION (RECOMPILE);

-- Sustained values above 10 suggest further investigation in that area
-- High current_tasks_count is often an indication of locking/blocking problems
-- High runnable_tasks_count is a good indication of CPU pressure
-- High pending_disk_io_count is an indication of I/O pressure
Error: User Rate Limit Exceeded Lee Tickett
Error: User Rate Limit Exceeded Lee Tickett
7

ad-hoc

Defragment the table

As long as we have a clustered index then we can defragment the table using DBCC INDEXDEFRAG (deprecated) or preferably ALTER INDEX. This will minimize the number of disk reads required to scan the table and will improve speed.

Use the fastest disks possible. You don't say what disks you're using but if you can use SSDs.

Optimize tempdb. Put tempdb on the fastest disks possible, again SSDs. See this SO Article and this RedGate article.

As stated in other answers, using a more selective query will return less data, and should be therefore be faster.

weren'tad-hocmost

Add a single column index to each column. This should give SQL Server at least something to work with to improve the speed for the majority of queries, but won't be optimal. Add specific indexes for the most common queries so they are optimized. Add additional specific indexes as required by monitoring for poorly performing queries.

Edit

0

50

осу).

Lack of index

Отсутствие индекса наer101_upd_date_iso колонка самая важная вещь, какError: User Rate Limit Exceeded уже упомянул.

Без сопоставления индекса (отсутствие которого может привести к сканированию таблиц) невозможно выполнить быстрые запросы для больших таблиц.

Если вы не можете добавить индексы (по разным причинам, включаяthere is no point in creating index for just one ad-hoc queryError: User Rate Limit Exceeded

1. Use temporary tables

Error: User Rate Limit ExceededcachedError: User Rate Limit Exceeded

Error: User Rate Limit Exceeded

-- copy records from last month to temporary table
INSERT INTO
   #my_temporary_table
SELECT
    *
FROM
    er101_acct_order_dtl WITH (NOLOCK)
WHERE 
    er101_upd_date_iso > DATEADD(month, -1, GETDATE())

-- you can add any index you need on temp table
CREATE INDEX idx_er101_upd_date_iso ON #my_temporary_table(er101_upd_date_iso)

-- run other queries on temporary table (which can be indexed)
SELECT TOP 100
    * 
FROM 
    #my_temporary_table 
ORDER BY 
    er101_upd_date_iso DESC

Error: User Rate Limit Exceeded

Easy to do for any subset of data. Easy to manage -- it's temporary and it's table. Doesn't affect overall system performance like view. Temporary table can be indexed. You don't have to care about it -- it's temporary :).

Минусы:

It's snapshot of data -- but probably this is good enough for most ad-hoc queries. 2. Common table expression -- CTE

Лично я пользуюсьКТР много для специальных запросов - это очень помогает при построении (и тестировании) запроса по частям.

Error: User Rate Limit ExceededWITH).

Error: User Rate Limit Exceeded

Easy to build starting from big view and then selecting and filtering what really you need. Easy to test.

Минусы:

Some people dislike CDE -- CDE queries seem to be long and difficult to understand. 3. Create views

Error: User Rate Limit Exceeded

Вы можете создавать виды илиError: User Rate Limit ExceededError: User Rate Limit Exceeded

Error: User Rate Limit Exceeded

Easy to do. It's up to date with source data.

Error: User Rate Limit Exceeded

Possible only for defined subset of data. Could be inefficient for large tables with high rate of updates. Not so easy to manage. Can affect overall system pe,rformance. I am not sure indexed views are available in every version of MS SQL. Selecting all columns

Error: User Rate Limit Exceededstar query (SELECT * FROMError: User Rate Limit Exceeded

Error: User Rate Limit Exceeded

Я бы попробовал заменить*Error: User Rate Limit Exceeded

Error: User Rate Limit Exceededcommon data expression):

;WITH recs AS (
    SELECT TOP 100 
        id as rec_id -- select primary key only
    FROM 
        er101_acct_order_dtl 
    ORDER BY 
        er101_upd_date_iso DESC
)
SELECT
    er101_acct_order_dtl.*
FROM
    recs
    JOIN
      er101_acct_order_dtl
    ON
      er101_acct_order_dtl.id = recs.rec_id
ORDER BY 
    er101_upd_date_iso DESC 
Dirty reads

Error: User Rate Limit Exceededdirty readsError: User Rate Limit ExceededError: User Rate Limit ExceededWITH (NOLOCK).

Error: User Rate Limit ExceededError: User Rate Limit ExceededError: User Rate Limit Exceeded

SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED

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Error: User Rate Limit Exceededdirty readsError: User Rate Limit Exceeded

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Error: User Rate Limit ExceededSELECT *Error: User Rate Limit Exceeded
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0

Error: User Rate Limit Exceeded
Error: User Rate Limit Exceededmsdn.microsoft.com/en-us/library/ms181714(v=sql.105).aspxError: User Rate Limit Exceededsocial.msdn.microsoft.com/Forums/en-US/transactsql/thread/…

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