Query Not Using Index
Jul 23, 2005
Hi,
I have a table t1 with columns a,b,c,d,e,f,g,h,i,j,k,l
I have created a clustered index on a,b,d,e which forms the primary
key. I have created a covering index on all the columns of t1. There
are 1 million rows in this table.
My query chooses the TOP20 rows based on some filter conditions. When
I use an "ORDER BY 1", it uses the clustered index and I get the result
in 1 second, whereas it takes around 1minute 48seconds when I use an
"ORDER BY b or any other column". It is not using the covering / the
clustered index.
What is the best way to index this table so that it uses the index and
I get the result within the shortest possible time (just like that of
ORDER BY 1 which take hardly a second).
Thanks..
Sridhar
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Nov 14, 2006
the query:
SELECT a.AssetGuid, a.Name, a.LocationGuid
FROM Asset a WHERE a.AssociationGuid IN (
SELECT ada.DataAssociationGuid FROM AssociationDataAssociation ada
WHERE ada.AssociationGuid = '568B40AD-5133-4237-9F3C-F8EA9D472662')
takes 30-60 seconds to run on my machine, due to a clustered index scan on our an index on asset [about half a million rows]. For this particular association less than 50 rows are returned.
expanding the inner select into a list of guids the query runs instantly:
SELECT a.AssetGuid, a.Name, a.LocationGuid
FROM Asset a WHERE a.AssociationGuid IN (
'0F9C1654-9FAC-45FC-9997-5EBDAD21A4B4',
'52C616C0-C4C5-45F4-B691-7FA83462CA34',
'C95A6669-D6D1-460A-BC2F-C0F6756A234D')
It runs instantly because of doing a clustered index seek [on the same index as the previous query] instead of a scan. The index in question IX_Asset_AssociationGuid is a nonclustered index on Asset.AssociationGuid.
The tables involved:
Asset, represents an asset. Primary key is AssetGuid, there is an index/FK on Asset.AssociationGuid. The asset table has 28 columns or so...
Association, kind of like a place, associations exist in a tree where one association can contain any number of child associations. Each association has a ParentAssociationGuid pointing to its parent. Only leaf associations contain assets.
AssociationDataAssociation, a table consisting of two columns, AssociationGuid, DataAssociationGuid. This is a table used to quickly find leaf associations [DataAssociationGuid] beneath a particular association [AssociationGuid]. In the above case the inner select () returns 3 rows.
I'd include .sqlplan files or screenshots, but I don't see a way to attach them.
I understand I can specify to use the index manually [and this also runs instantly], but for such a simple query it is peculiar it is necesscary. This is the query with the index specified manually:
SELECT a.AssetGuid, a.Name, a.LocationGuid
FROM Asset a WITH (INDEX (IX_Asset_AssociationGuid)) WHERE
a.AssociationGuid IN (
SELECT ada.DataAssociationGuid FROM AssociationDataAssociation ada
WHERE ada.AssociationGuid = '568B40AD-5133-4237-9F3C-F8EA9D472662')
To repeat/clarify my question, why might this not be doing a clustered index seek with the first query?
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Oct 20, 2006
please explain the differences btween this logical & phisicall operations that we can see therir graphical icons in execution plan tab in Management Studio
thank you in advance
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May 9, 2006
MS SQL Server 2000 SP3
I'm not the most knowledgable DBA, I've had to learn almost completely on my own, AND on a production server, because it's the only MS SQL Server I have access to.
Everything was fine before I took down the production server for maintenance. Someone suggested that I re-index my tables because I was having some performance issues with a particularly large table (it didn't help that table btw), so I did re-index.
Now, Everything works wonderfully, except for the performance issue mentioned AND one other thing that is going horribly wrong.
Here is the table:
create table ABMcontactlink
(
classifier varchar(20) not null, /* Classification of contact. */
transmitter varchar(36) not null,
contact integer not null, /* Link to ABMcontact (detail) table */
primary key (classifier,transmitter,contact),
foreign key (contact) references ABMcontacts(identifier),
group_name varchar(20) null,
priority smallint null, /* Authorization level. */
type smallint null, /* Autoalarm or Manual */
last_modification_date datetime, /* Date/time record last touched */
last_modification_id varchar(40) /* Who last touched record */
)
go
create index IndexABMcontactlink on
ABMcontactlink(classifier,transmitter)
go
create index CandidateABMcontactlink on
ABMcontactlink(transmitter)
go
As you can see, I have the primary key, which creates a clustered index, PK_ABMContactlink_Some Number, and two other indexes.
Now, this is a very busy production database, and most quick short queries benefit more from CandidateABMContactlink than from the other two indexes.
Unfortunately, in this production system, and this table, seconds count ALOT, so when I have roughly 3000-4000 quereies an hour pulling information from this table, I personally beleive I need to keep CandidateABMContactlink, and I'm not willing to find out on a production server.
** Now to the Problem at Hand **
I have one query that kicks off about 7 times a day, used to take less than 1 minute before the re-index. NOW it takes 30 Minutes. And it drags the system to a crawl.
I did some looking into it, and this query is using CandidateABMContactlink, and it takes 30 minutes. If it uses PK_Abmcontactlink it finishes in under 45 seconds.
Most queries are simple, "Select Column_names from abmcontacts where identifier in (select contact from abmcontactlink where transmitter = 'XXXXXX')"
This one is:
select * from ABMcontacts where (
(last_modification_date >= '2006-04-28 04:40:03' and last_modification_date <= '2006-05-09 16:41:14')
and EXISTS(select contact from ABMcontactlink where contact = identifier
and EXISTS(select transmitter_id from ABMtransmitter where transmitter_id = transmitter and (dealer = 'XXXX'))))
or
(EXISTS(select contact from ABMcontactlink where
(last_modification_date >= '2006-04-28 04:40:03' and last_modification_date <= '2006-05-09 16:41:14')
and contact = identifier and EXISTS(select transmitter_id from ABMtransmitter where transmitter_id = transmitter and (dealer = 'XXXX'))))
I can't change the query, so how do I make it use the Index I want it to use without removing the index that it is using? (I know there are much better ways to write the above query, I'm not the culprit, if I could re-write it, I would)
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Aug 24, 2001
Hi,
I have 2 identical DB on the same server with the same indexes on both db, but when I run a query using query analyzer, on db A it will take 6 sec but run the same query on db B it will take 1 minute. I checked the indexes on all tables in 2 db's are the same.
I used show execution plan, it does show that it is not using some indexes on the 2nd db, I droped all indexes and rebuild them again, but the same result.
Any idea why it is taking so long on the other db.
Thanks
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Mar 12, 2001
I have a view (table_rol_contct) on a number of tables, one of which is a table of address data (table_address). This table has a unique, non-clustered index on Postcode, House Number and an Id column (idx_x_s_postcode). There is a clustered index on the Id column.
There are a number of queries which are run against this view, one of which selects addresses whose Postcode matches a full or partial Postcode entered through a Client Application.
This query :
Select distinct top 30
con.salutation+' '+con.first_name+' '+con.last_name as fullname,
con.title,
con.phone,
con.x_housename,
con.x_houseno,
con.x_housename+' '+con.x_houseno+' '+con.address+', '+con.address_2+' '+con.city as fulladdress,
from table_rol_contct con
where con.x_s_postcode like 'wf18%'
order by con.last_name asc, con.first_name asc
returns its results in under a second while this one:
Select distinct top 30
con.salutation+' '+con.first_name+' '+con.last_name as fullname,
con.title,
con.phone,
con.x_housename,
con.x_houseno,
con.x_housename+' '+con.x_houseno+' '+con.address+', '+con.address_2+' '+con.city as fulladdress,
from table_rol_contct con
where con.x_s_postcode like 'wf3%'
order by con.last_name asc, con.first_name asc
takes 38 seconds to returns its results.
The execution plans for these queries show that the slow query uses a Clustered Index Scan whereas the quick one uses an index seek on the ‘idx_x_s_postcode’ non-clustered index.
dbcc show_statistics (table_address, idx_x_s_postcode)
shows that this index has 300 steps with these representing the ones relevant to the above queries:
..., WF169AG, WF175NN, WF178BY, WF20HN, WF27ET, WF28TP, WF31PZ, WF34EF, WF42HL, ...
From this, you can see that ‘WF18%’ is wholly contained in a single step and the optimizer appears to happily perform an index seek, whereas ‘WF3%’ spans more than 1 so the optimizer seems to choose a clustered index scan.
Is there any way that I can force the use of the non-clustered index or, at least, make it more likely that the optimizer will use this index without coding an optimizer hint into the ‘Create View’ statement? The problem is that the view is used for other queries, all the queries run against it are generated from within a client application and the given search criteria could, for example, be ‘con.address’ rather than ‘con.x_s_postcode’.
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Aug 11, 2005
Hi,I am making as SELECT query to fill a repeater, and I need to retrieve the index of each line of the query.ie, I want to get a dataset like :"0", "dataCol1", "dataCol2" for the first line"1", "dataCol1", "dataCol2" for the second line"2", "dataCol1", "dataCol2" for the third lineetc.Anyone knows if there is a sql statement that does it ?ThanksJohann
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Nov 4, 2000
hi, what are the tools that I can use to Optimize the query/ index.
I know that if I am running a query on a table I create index on the fields where I use in the where clause, is this a right thinking.
Someone told me how do I determine what columns should be indexed, I told him the fields that I use in the where clause should be indexed to speed up the process of retrieving the data. ..... is this answer correct. if not please advice the correct one.
Thanks
Ahmed
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Feb 27, 2007
Not sure which forum too put this question
I have recently upgraded my Access Database too use SQL server 2005 using the upsizing wizard. I have selected too use SQL Linked tables instead off the ADP project for ease off conversion. So now the tables are on the SQL server and the queries are still local.
On off my Access forms which returns a datasheet view by accessing the a query is now running really slowly now SQL server is the backend, I was wondering if I can put an index on one of the tables too speed it up, as the query is local too Access will this work? Just wondering if anyone ever come across this.
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Jun 27, 2007
I am trying to resolve performance issues in a third party application. I have run the profiler and found a transaction that performs a table scan against a 6 million row table. This transaction occurs repeatedly, so I thought, just add an index on the columns in the where clause used here. After adding the index, I looked at the estimated execution plan in Query analyzer, and I find that it is still performing the table scan. If I run the query it takes over 60 seconds to run, if i add an index hint, it runs in under a second. I ran DBCC SHOW_STATISTICS to see if the statistics were up to date:
Statistics for INDEX 'IX_Finish_dept'.
Updated Rows Rows Sampled Steps Density Average key length
-------------------- -------------------- -------------------- ------ ------------------------ ------------------------
Jun 26 2007 5:18PM 6832336 6832336 150 2.1415579E-7 18.0
(1 row(s) affected)
All density Average Length Columns
------------------------ ------------------------ ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
2.1875491E-7 8.0 finish
1.9796084E-7 18.0 finish, dept
(2 row(s) affected)
RANGE_HI_KEY RANGE_ROWS EQ_ROWS DISTINCT_RANGE_ROWS AVG_RANGE_ROWS
------------------------------------------------------ ------------------------ ------------------------ -------------------- ------------------------
1900-01-01 00:00:00.000 0.0 106110.0 0 0.0
2001-02-01 17:00:00.000 54121.0 47.0 22951 2.3581107
2001-02-28 17:00:00.000 44436.0 22.0 18121 2.4520473
2001-04-06 00:00:00.000 56830.0 76.0 24902 2.2820544
2001-08-10 17:00:00.000 196491.0 19.0 88800 2.2127116
2001-09-02 17:00:00.000 33070.0 50.0 15289 2.162993
2001-10-05 17:04:59.997 57975.0 30.0 22882 2.5335402
2001-11-05 15:31:59.997 50178.0 21.0 20899 2.4008613
2001-12-10 17:00:00.000 55266.0 38.0 25114 2.2006052
2002-01-03 17:00:00.000 40322.0 51.0 18649 2.1620376
2002-02-25 17:00:00.000 86338.0 24.0 39266 2.1987979
2002-08-15 06:11:00.000 296085.0 166.0 124526 2.3776772
2002-10-07 21:18:59.997 88727.0 826.0 39017 2.2740018
2002-12-17 16:59:00.000 127671.0 6.0 53314 2.3946545
2003-01-16 07:15:00.000 62206.0 71.0 24604 2.5281854
2003-01-21 07:15:00.000 8287.0 43.0 3661 2.2629712
2003-01-27 07:15:00.000 10402.0 68.0 4265 2.4389215
2003-01-31 07:15:00.000 9127.0 73.0 3784 2.4113607
2003-02-05 00:00:00.000 8362.0 327.0 3500 2.3891428
2003-02-10 00:00:00.000 8846.0 262.0 3230 2.7386997
2003-02-14 00:00:00.000 10018.0 51.0 4107 2.4386563
2003-02-20 00:00:00.000 10388.0 91.0 4686 2.2168159
2003-02-26 00:00:00.000 10571.0 69.0 4330 2.4407759
2003-03-03 00:00:00.000 10476.0 261.0 4423 2.3679929
2003-03-06 00:00:00.000 8858.0 594.0 3183 2.7829092
2003-04-02 00:00:00.000 57681.0 275.0 38622 1.4934366
2003-04-05 00:00:00.000 10539.0 29.0 8776 1.2008888
2003-04-09 00:00:00.000 9880.0 1324.0 7193 1.3735576
2003-04-12 00:00:00.000 8953.0 195.0 7737 1.1571668
2003-04-16 00:00:00.000 8385.0 177.0 7154 1.1719078
2003-04-21 00:00:00.000 8920.0 173.0 7756 1.1500773
2003-04-24 00:00:00.000 8563.0 156.0 7320 1.169649
2003-04-29 00:00:00.000 8462.0 137.0 7414 1.1412003
2003-05-02 00:00:00.000 9625.0 140.0 8363 1.1509027
2003-05-06 00:00:00.000 8208.0 904.0 6557 1.251792
2003-05-09 00:00:00.000 9211.0 119.0 7986 1.1533934
2003-05-19 00:00:00.000 19623.0 123.0 17290 1.1348679
2003-05-22 00:00:00.000 9568.0 246.0 8357 1.1449084
2003-05-28 00:00:00.000 9599.0 169.0 8553 1.1221651
2003-06-02 00:00:00.000 10937.0 174.0 9599 1.1393895
2003-07-11 00:00:00.000 99592.0 999.0 83573 1.1916767
2003-07-29 00:00:00.000 42434.0 111.0 33918 1.2510761
2003-08-21 00:00:00.000 59580.0 323.0 50756 1.1738282
2003-09-12 00:00:00.000 51779.0 1407.0 44298 1.1688789
2003-09-25 00:00:00.000 30655.0 255.0 26924 1.138533
2003-10-12 00:00:00.000 44573.0 968.0 37746 1.1808668
2003-10-28 00:00:00.000 38358.0 532.0 32689 1.1734222
2003-11-11 00:00:00.000 35158.0 145.0 28124 1.2500622
2003-12-04 00:00:00.000 61304.0 787.0 52882 1.1592383
2003-12-18 00:00:00.000 44462.0 221.0 39493 1.1257913
2004-01-06 00:00:00.000 56617.0 998.0 49471 1.1444252
2004-02-04 00:00:00.000 96694.0 537.0 83182 1.162425
2004-03-05 00:00:00.000 90850.0 716.0 78693 1.1544864
2004-03-23 00:00:00.000 48969.0 125.0 43450 1.1270195
2004-07-05 00:00:00.000 301725.0 1405.0 258824 1.1657491
2004-08-06 00:00:00.000 95079.0 1419.0 75445 1.2602259
2004-09-03 00:00:00.000 88056.0 193.0 68403 1.2873119
2004-09-23 01:30:12.997 57515.0 8.0 42891 1.3409261
2004-10-11 00:00:00.000 57204.0 116.0 40241 1.4215
2004-10-15 00:00:00.000 17702.0 186.0 12774 1.3856752
2004-10-19 00:00:00.000 9556.0 125.0 7305 1.3079661
2004-10-21 00:00:00.000 8898.0 133.0 6299 1.4126052
2004-10-25 00:00:00.000 8878.0 104.0 6372 1.3930645
2004-10-27 00:00:00.000 11904.0 252.0 6056 1.9656539
2004-10-29 00:00:00.000 8866.0 99.0 6551 1.3533812
2004-11-02 15:22:47.997 12287.0 1.0 9791 1.2547998
2004-11-05 13:16:50.997 12287.0 1.0 10013 1.2269822
2004-11-09 23:52:48.000 12284.0 4.0 9200 1.3352174
2004-11-12 17:17:59.997 12287.0 1.0 9360 1.3127136
2004-11-22 06:58:06.997 24575.0 1.0 19742 1.244745
2004-11-25 01:57:00.000 12287.0 1.0 8822 1.392768
2004-11-30 21:34:59.997 12287.0 1.0 9128 1.3459306
2004-12-03 13:21:24.000 12287.0 1.0 9085 1.3523003
2004-12-07 04:05:21.000 12285.0 5.0 9488 1.2947934
2004-12-09 13:25:00.000 12285.0 5.0 8993 1.3659106
2004-12-13 07:21:46.000 12282.0 10.0 9461 1.2981714
2004-12-15 18:41:23.000 12287.0 2.0 9112 1.3482937
2005-02-04 14:41:36.997 178768.0 58.0 133439 1.3396883
2005-02-23 00:00:00.000 51107.0 29.0 38624 1.3231586
2005-03-10 23:06:17.997 50891.0 24.0 38479 1.3225312
2005-03-28 00:00:00.000 45509.0 32.0 34203 1.3305169
2005-04-13 09:50:34.000 58778.0 19.0 43687 1.3454038
2005-06-08 09:46:43.997 162983.0 25.0 121508 1.3413246
2005-08-08 09:37:29.000 197467.0 20.0 143462 1.3764411
2005-08-24 11:21:37.997 57393.0 5.0 42770 1.3418672
2005-09-11 13:54:05.997 53729.0 5.0 39527 1.3592987
2005-11-08 00:00:00.000 193537.0 69.0 136906 1.4136385
2005-11-22 00:00:00.000 55031.0 33.0 38197 1.4407152
2005-12-05 00:00:00.000 40371.0 77.0 28082 1.4376112
2005-12-22 12:40:59.997 75170.0 3.0 52523 1.4311825
2006-03-02 00:00:00.000 239709.0 42.0 170405 1.4066935
2006-03-04 06:26:36.997 9639.0 23.0 6470 1.489799
2006-03-12 10:02:43.000 21993.0 1.0 16086 1.3672137
2006-03-15 00:00:00.000 8774.0 40.0 6687 1.3119019
2006-04-03 00:00:00.000 69570.0 31.0 46495 1.4962578
2006-04-04 00:00:00.000 8743.0 28.0 4606 1.8977643
2006-04-04 13:53:00.997 12284.0 6.0 3401 3.6108172
2006-04-05 00:00:00.000 10794.0 29.0 3438 3.139616
2006-04-06 00:00:00.000 9413.0 45.0 5001 1.8818473
2006-04-10 00:00:00.000 11058.0 30.0 7865 1.4059758
2006-04-14 00:00:00.000 23183.0 38.0 16281 1.4238423
2006-04-18 00:00:00.000 9898.0 37.0 7258 1.3635488
2006-04-21 03:19:31.000 16561.0 26.0 11848 1.3976707
2006-04-25 14:48:00.000 12287.0 3.0 8553 1.436572
2006-04-27 13:37:49.000 9793.0 96.0 7203 1.3593837
2006-05-02 00:00:00.000 11426.0 30.0 8135 1.4043757
2006-05-04 05:28:36.000 12277.0 22.0 8806 1.3940048
2006-06-08 00:00:00.000 123695.0 33.0 89478 1.3824068
2006-06-16 00:00:00.000 35327.0 37.0 24539 1.4396267
2006-06-29 00:00:00.000 48433.0 40.0 35226 1.3748829
2006-07-14 00:00:00.000 62915.0 57.0 44859 1.4024744
2006-08-10 00:00:00.000 106281.0 36.0 75810 1.401939
2006-08-17 00:00:00.000 25345.0 81.0 18123 1.398422
2006-08-28 00:00:00.000 40947.0 38.0 27573 1.4850397
2006-09-11 09:00:00.000 52187.0 15913.0 36698 1.4220666
2006-09-25 00:00:00.000 52902.0 30.0 37210 1.4216764
2006-10-06 00:00:00.000 54534.0 31.0 38244 1.4259119
2006-10-11 13:29:40.997 16380.0 5.0 12503 1.3100855
2006-11-29 00:00:00.000 197522.0 27.0 138746 1.423623
2006-12-01 00:00:00.000 10584.0 24.0 7602 1.3920821
2007-01-02 00:00:00.000 141284.0 34.0 101246 1.3954526
2007-01-12 02:57:03.997 60416.0 23.0 41700 1.4488249
2007-02-13 00:00:00.000 156270.0 75.0 109875 1.4222525
2007-02-16 00:00:00.000 17770.0 38.0 12325 1.441668
2007-03-05 12:23:00.000 73763.0 3.0 51503 1.43218
2007-03-08 04:11:49.997 16407.0 22.0 11428 1.4355587
2007-03-26 09:10:43.000 76336.0 20.0 53687 1.4218712
2007-04-05 12:31:28.000 64126.0 24.0 40172 1.5962859
2007-04-07 01:11:22.000 9244.0 28.0 6657 1.388405
2007-04-10 00:00:00.000 8924.0 38.0 6140 1.4531835
2007-04-24 21:01:00.000 73487.0 6.0 51689 1.421687
2007-04-26 09:01:48.997 9584.0 25.0 6650 1.441203
2007-04-28 04:09:21.000 9801.0 27.0 7037 1.3925831
2007-05-01 12:55:00.000 8781.0 26.0 6012 1.460336
2007-05-03 00:00:00.000 10570.0 53.0 7298 1.4481436
2007-05-04 21:49:27.000 12287.0 1.0 8680 1.415553
2007-05-08 06:06:45.997 8202.0 27.0 5511 1.4880261
2007-05-10 00:00:00.000 10920.0 49.0 7973 1.3696225
2007-05-12 00:44:10.000 11375.0 27.0 8223 1.3833151
2007-05-15 10:51:50.000 9453.0 27.0 6516 1.4507366
2007-05-18 08:44:36.997 17930.0 27.0 12651 1.4172792
2007-05-22 00:00:00.000 10089.0 74.0 7260 1.3894781
2007-05-23 21:07:38.000 12286.0 3.0 8604 1.4279405
2007-05-26 03:46:02.000 12287.0 6.0 8545 1.4377487
2007-05-30 21:24:29.997 12287.0 1.0 8663 1.4183308
2007-06-01 18:37:16.000 12287.0 1.0 8401 1.4623899
2007-06-05 00:00:00.000 9255.0 52.0 6491 1.4256008
2007-06-08 22:18:40.000 24574.0 3.0 17047 1.4415439
2007-06-12 09:42:14.997 9550.0 31.0 6410 1.4896272
9200-12-08 09:49:59.997 64286.0 1.0 45408 1.4157417
(150 row(s) affected)
What can I do to get SQL to use this index?
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Nov 12, 2001
I'm looking for a query that will return all index names, the table the index is on and the columns in the index...
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Jun 21, 2004
create table t1(a varchar(50) , b varchar(50))
create index i1 on t1(a)
create index i2 on t1(b)
create view v1
as
select * from t1 where isnull(a,b) = 'test'
select * from v1
The above SQL "select * from v1" is doing a table scan.
What do I do to make it perform an index seek ????
TIA
- ForXLDB
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Jul 28, 2014
I am trying to create an index for a specific query that is used a lot.
Unfortunately I am keep getting a clustered index scan. (4.6 mil rows)
Googling "AND" and "OR" is tricky, but did lead met to many articles about filtered indexes.
None of which gave me a clear answer.
How can I make an index for this query?
Here's the code setup
------------------------------------------------------------------------------------------
-- Setup
------------------------------------------------------------------------------------------
IF OBJECT_ID('FilterTbl') IS NOT NULL
DROP TABLE FilterTbl
CREATE TABLE FilterTbl
(
SurroIDInt IDENTITY PRIMARY KEY,
CompIDSmallInt,
[code]....
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Dec 28, 2014
This is my table:
use tempdb
go
if object_id('Data', 'u') is not null drop table Data
go
with temp as (
select top 10000 row_number() over (order by c1.object_id) Id
from sys.columns c1 cross join sys.columns c2
[code]....
What index would be best for these three queries? With best I mean the execution time, I don't care about additional space.
This is the index I currently use:
create nonclustered index Ix_Data on Data (StateId, PalletId, BoxId, Id)
The execution plan is SELECT (0%) - Stream Aggregate (10%) - Index Scan (90%).
Can this be optimized (maybe to use Index Seek method)?
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Jul 28, 2015
Running SQL 2012 SP2
I've got this query that runs in 30 seconds and returns about 24000. The table variable returns about 145 rows (no performance issue here), and the TransactionTbl table has 14.2 Million rows, a compound, clustered primary key, and 6 non-clustered indexes, none of which meet the needs of the query.
declare @CltID varchar(15) = '12345'
declare @TranDate datetime = '2015-07-25'
declare @Ballance table
(Ledger_Code varchar(4),
AssetID varchar(32),
CurrencyID varchar(3) )
[Code] ....
Actual execution plan shows SQL is doing an index seek, then a nested loop join, and then fetching the remaining data from the TransactionTbl using a Key Lookup.
I designed a new indexes based on the query, which when I force it's usage via an index hint, reduces the run time to sub-second, but without the index hint the SQL optimiser won't use the new index, which looks like this:
CREATE INDEX IX_Test on GLSchemB.TransactionTbl (CltID, Date) include (Ledger_Code, Amount, CurrencyID, AssetID)and I tried this:
CREATE INDEX IX_Test on GLSchemB.TransactionTbl (CltID, Date, Ledger_Code, CurrencyID, AssetID) include (Amount)and even a full covering index!
I did some testing, including disabling all indexes but the PK, and the optimiser tells me I've got a missing index and recommends I create one EXACTLY like the one I designed, but when I put my one back it doesn't use it.
I though this may be due to fragmentation and/or stats being out of date, so I rebuilt the PK and my index, and the optimiser started using my index, doing an index seek and running sub-second. Thinking I had solved the problem I rebuilt all the indexes, testing after each one, and my index was used BUT as soon as I flushed the related query plan, the optimiser went back to using a less optimal index, with a seek and key lookup plan and taking 30 seconds.
For now I've resorted to using the OPTION (TABLE HINT(G, INDEX(IX_Test))) to force this, but it's a work around only. Why the optimiser would select a less optimal query plan?
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Jul 20, 2005
I have a table that seems to have a bad index. When I do the followingquery I get inconsistant and needless to say incorrect results.select count(*) from mytable where mycolumn = 1If I remove the index from "mycolumn" the query works correctly. If Iadd the index back (even with a new name etc...) it doesn't workright.Has anyone ran into this? or does anyone know how I can fix thisproblem?It seems that removing the index is not really removing everythingbecause when I add a new one I get this same problem... btw, this isisolated to this column on this table. all other indexes within thedatabase are fine.Any help would be appreciated.Thanks,dharper
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Apr 29, 2008
I have one query that looks like this.
DECLARE @propname
SET @propname = NULL -- can be Null or have wild card values
SELECT col1, col2, col3, propertyname FROM testtable where col1 = 1 and col2 = 2 and col3 = 3 and (@propname IS NULL OR propertyname LIKE @propname)
col1, col2, col3 are part of a clustered index
propertyname is a nonclustered index
This is the predicament. If the "@propname is NULL" is first in the OR statement then the query will use the clustered index for finding the record. If I put "@propname is NULL" last then it uses the propertyname index no matter what. So I either get full index scans if NULL is ever used on property names or I get consistent two second long searches on the clustered index. Any way to have the best of both worlds? Or do I have to divide up my query into more stored procedures?
THANKS
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Nov 16, 2007
I have the following table:
Create Table Item(
I_Code NVarChar(40) Primary Key NOT NULL,
I_MatID NVarChar(40),
I_Name NVarChar(160),
I_BC nvarchar(20),
I_Company nvarchar(20),
I_CompanyFound nvarchar(20),
I_Info1 nvarchar(55),
I_Acquired nvarchar(35),
I_Info2 nvarchar(55),
I_Info3 nvarchar(55),
I_Date DateTime DEFAULT GetDate()
);
Create Index ind_Item_Name on Item(I_Name);
Create Index ind_Item_BC on Item(I_BC);
Create Index ind_Item_Company on Item(I_Company);
Create Index ind_Item_CompanyFound on Item(I_CompanyFound);
create Index ind_Item_i1 on Item(I_Company,I_CompanyFound);
create Index ind_Item_i2 on Item(I_CompanyFound,I_Company);
Now this query DOES NOT use index:
select I_Name, I_Code, I_MatID, I_BC, I_Company,I_Info1, I_Acquired, I_CompanyFound, 0 as I_Found
from Item
where (I_Company='102' or I_CompanyFound='102' )
While this one use:
select I_Name, I_Code, I_MatID, I_BC, I_Company,I_Info1, I_Acquired, I_CompanyFound, 0 as I_Found
from Item
where (I_Company='102' )
UNION
select I_Name, I_Code, I_MatID, I_BC, I_Company,I_Info1, I_Acquired, I_CompanyFound, 0 as I_Found
from Item
where (I_CompanyFound='102' )
Both return the same rows. Is this a bug? I found the following:
http://support.microsoft.com/kb/223423
Some feedback?
Thanks
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Mar 20, 2007
We are using SQL2005.
I have a stored proc that runs a Select query based on a complex view.
The sproc has two input date parameters (StartDate and EndDate).
We are experiencing SQL timeout problems when the sproc is run with certain Start and End Dates.
We have run the SQL Profiler and created a trace (trc) file (We've used the 'Default' trace configuration).
We have used the trace file in SQL Server Management Studio to try and automatically create indexes on some of our tables.
Unfortunatly SQL Server Management does not make any index recommendations.
I think we are not capturing the right information in our trace file to allow SQL Server Management Studio to do its job.
How do I use SQL Profiler to capture a trace of my sprocs query, so that it can be used by SQL Server Management Studio, to recommend index changes?
Any help appreciated.
Reagrds,
Paul.
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Jan 15, 1999
I have an index that shows distribution statistics of 98.20%, which is very poor. I set show query plan and show statis I/O on. This table has 1113675 rows of data.
*************
select orderID, custId, intertcsi from tblorders
where intertcsi = '2815'
STEP 1
The type of query is SELECT
FROM TABLE
tblorders
Nested iteration
Index : indxInterTCSI
orderID custId intertcsi
----------- ----------- ---------
1015245 1011313 2815
2556392 2556392 2815
....
Table: tblOrders scan count 1, logical reads: 104, physical reads: 58, read ahead reads: 0
***************
Then I use the same select statement to force a table scan:
select orderID, custId, intertcsi from tblorders (index=0)
where intertcsi = '2815'
STEP 1
The type of query is SELECT
FROM TABLE
tblorders
Nested iteration
Table Scan
orderID custId intertcsi
----------- ----------- ---------
60472 61084 2815
102184 102333 2815
...
Table: tblOrders scan count 1, logical reads: 110795, physical reads: 6891, read ahead reads: 103980
When the index is not provided, the logical reads and physical reads increased dramatically. Does this tell me that I should keep that index though it is a poor selection? Is that because a huge table like this make the optimizer use the index. The query without using index takes longer time to run.
Any idea or comment would be very appreciated.
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Jul 30, 2007
For demonstration I created a fulltext index on table employee in Northwind database.
The following query gives an error:
SELECT * FROM employees
WHERE CONTAINS (FirstName, 'Barbe')
Replacing 'Barbe' by 'Barb' or other words it works fine.
The error message is (I have a french version of SQL installed, here the translation: "A clause in the query contains only ignored words"
Une clause de la requête ne contient que des mots ignorés)
Language for wordbreak in fulltext index is French and the error happens only with French, with English it works.
Is this a Microsoft bug?
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Oct 26, 2006
Greetings,
I have two tables:
CustomerOrder
----
ID
CustomerID
StatusID
CustomerOrderDetail
----
ID
Order_ID
StockID
Quantity
CustomerOrderDetail table has clustered unique index for ID and non-clustered for Order_ID
SQL Server 2005 is using table scan for CustomerOrderDetail table When I user the following query:
select
cod.*
from CustomerOrder co
inner join CustomerOrderDetail cod ON cod.Order_ID = co.ID
where
co.StatusID = 8 -- Pending
Both of the tables are pretty big, detail table has more than million records, so scanning the table is a bad idea.
When I specify hint to use index then sql seeks, but how do I make SQL server to use index automatically? I don't want to use hints in my queries.
Thanks!
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Nov 14, 2007
Hello all.
I have the following table
Create Table Item(
I_AssetCode NVarChar(40) Primary Key NOT NULL,
I_Name NVarChar(160),
I_BC nvarchar(20),
I_Company nvarchar(20)
);
Create Index ind_Item_Name on Item(I_Name);
Create Index ind_Item_BC on Item(I_BC);
Create Index ind_Item_Company on Item(I_Company);
It is populated with 50 000 records.
Searching on indexed columns is fast, but I've run into the following problem:
I need to get all distinct companies in the table.
I've tried with these two queries, but they both are very slow!
1. "select I_Company from item group by I_Company " - This one takes 19 seconds
2. "select distinct(I_Company) from item" -This one takes 29 secons
When I ran them through the SQL Management Studio and checked the performance plan, I saw that the second one doesn't use index at all ! So I focused on the first...
The first one used index (it took it 15% of the time), but then it ran the "stream aggregate" which took 85% of the time !
Actully 15% of 19 seconds - about 2 seconds is pretty much enough for me. But it looks that aggregate function is run for nothing!
So is it possible to force the query engine of the SSCE not to run it, since there is actually no aggregate functions in my select clause?
According to SQL CE Books online:
Group By
"Specifies the groups (equivalence classes) that output rows are to be placed in. If aggregate functions are included in the SELECT clause <select list>, the GROUP BY clause calculates a summary value for each group."
It seems the aggregate is run every time, not only when there is an aggregate function.
Is this a bug?
Thanks in advance,
TipoMan
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May 11, 2007
We are running MS RS and SQL Server 2000 SP3.
We have one LEDGER, where all the daily activities are stored. The LEDGER table has 4 indexes (1 clustered and 3 non-clustered). To get AR we use this table.
Well problem is some times in 1-2 months, any simple AR query takes a long time and every other client gets slow response (queries are very slow or sometimes block).
If we DROP any index on LEDGER table and again put it back (RECREATE), all our queries work fine and faster. This goes on till 1-2 months, till we see the same issue again.
This is a classic case happened today. Queries were running fine till morning 8 AM. We upload some 50 thousand records to Ledger table (Data Conversion). Well after 30 mins, all simple AR queries started taking a long time. We DROPPED an index in LEDGER table and everything was faster....Just to be same we added back the same index again.......everything is Faster.....
What is this. ....is it our QUERY, index or huge Transactions or no free space ???
We are scheduled to run SP4, next week. But is there any solution in the mean time on what is this?
Also is they any way to KILL all SQL server processes that take more than a mins. We just don't want ALL our client to Slow down because of one query????
Thanks,
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Jul 27, 2015
I had some SQL queries which are using department ID for join , filter , Group By and Select so , i am having index on department ID of my table File Master scheme ..
CREATE TABLE [dbo].[FILE_MASTER](
[FILE_ID] [INT] IDENTITY(1,1) NOT NULL,
[DEPARTMENT_ID] [INT] NULL,
    [CLIENT_ID] [INT] NULL
    ,[LEAD_DETAIL_ID] [INT] NULL
[code]....
The above index only working when there is condition or group by on department ID .and i when i am querying ..
SELECT DISTINCT CL.CLIENT_ID,CL.LOAN_SANCTION_DATE,MIN(CL.INWARD_DATE)AS Inward
FROM dbo.FILE_MASTER AS CLÂ
GROUP BY CL.CLIENT_ID,CL.LOAN_SANCTION_DATE
and the plan is showing Index scan on index Indx_FM_department_ID .. Why it is not using Index seek , i guess i have both group by Columns in cover index included columns what is the use of cover index then ?
because if i am giving where condition before group by for specific Client ID , Loan Sanction Date it is telling to create separate index on client ID , Loan Sanction Date as per Execution Plan missing index detail ..
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Apr 29, 2015
I want to create index for hash table (#TEMPJOIN2) to reduce the update query run time. But I am getting "Warning!
The maximum key length is 900 bytes. The index 'R5IDX_TMP' has maximum length of 1013 bytes. For some combination of large values, the insert/update operation will fail". What is the right way to create index on temporary table.
Update query is running(without index) for 6 hours 30 minutes. My aim to reduce the run time by creating index.Â
And also I am not sure, whether creating index in more columns will create issue or not.
Attached the update query and index query.
CREATE NONCLUSTERED INDEX [R5IDX_TMP] ON #TEMPJOIN2
(
[PART] ASC,
[ORG] ASC,
[SPLRNAME] ASC,
[REPITEM] ASC,
[RFQ] ASC,Â
[Code] ....
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Sep 30, 2015
I am using Full Text Index to index emails stored in BLOB column in a table. Index process parses stored emails, and, if there is one or more files attached to the email these documents get indexed too. In result when I'm querying the full text index for a word or phrase I am getting reference to the email containing the word of phrase if interest if the word was used in the email body OR if it was used in any document attached to the email.
How to distinguish in a Full Text query that the result came from an embedded document rather than from "main" document? Or if that's not possible how to disable indexing of embedded documents?
My goal is either to give a user an option if he or she wants to search emails (email bodies only) OR emails AND documents attached to them, or at least clearly indicate in the returned result the real source where the word or phrase has been found.
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Dec 5, 2007
Dear All.
We had Teradata 4700 SMP. We have moved data from TD to MS_SQL SERVER 2003. records are 19.65 Millions.
table is >> Order_Dtl
Columns are:-
Client_ID varchar 10
Order_ID varchar 50
Order_Sub_ID decimal
.....
...
..
.
Pk is (ClientID+OrderId+OrderSubID)
Web Base application or PDA devices use to initiate the order from all over the country. The issue is this table is not Partioned but good HP with 30 GB RAM is installed. this is main table that receive 18,0000 hits or more. All brokers and users are using this table to see the status of their order.
The always search by OrderID, or ClientID or order_SubNo, or enter any two like (Client_ID+Order_Sub_ID) or any combination.
Query takes to much time when ever server receive more querys. some orther indexes are also created on the same table like (OrderDate, OrdCreate Date and Status)
My Question are:-
Q1. IF Person "A" query to DB on Client_ID, then what Index will use ? (If any one do Query on any two combination like Client_ID+Order_ID, So what index will be uesd.? How does MS-SQL SERVER deal with these kind of issues.?
Q2. If i create 3 more indexes on ClientID, ORderID and OrdersubID. will this improve the performance of query.if person "A" search record on orderNo so what index will be used. (Mind it their would be 3 seprate indexes for Each PK columns) and composite-Clustered index is also available.?
Q3. I want to check what indexes has been used? on what search?
Q4. How can i check what table was populated when, or last date of update (DML)?
My Limitation is i Dont Create a Partioned table. I dont have permission to do it.
In Teradata we had more than 4 tb record of CRM data with no issue. i am not new baby in db line but not expert in sql server 2003.
I am thank u to all who read or reply.
Arshad
Manager Database
Esoulconsultancy.com
(Teradata Master)
10g OCP
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Oct 28, 2015
My SSIS package is running very slow taking so much time to execute, One task is taking 2hr for inserting 100k records, i have disabled unused index still it is taking time.I am rebuilding/Refreshing indexes and stats once in month if i try to execute on daily basis will it improve my SSIS Package performance?Â
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Jan 22, 2006
Keep getting this error when positioning to the last page of a report.
Using Server 2003...SqlRpt Svcs 2000 sp2
Detail error msg:
Exception of type Microsoft.ReportingServices.ReportRendering.ReportRenderingException was thrown. (rrRenderingError) Get Online Help
Exception of type Microsoft.ReportingServices.ReportRendering.ReportRenderingException was thrown.
Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index
Anyone have any suggestions? Any way to find out what collection is blowing?...or where parameter name: index comes from?
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Jun 20, 2008
hello friends
i have table1 and 200 coulumn of table1 :) i have 647.600 records. i entered my records to table1 with for step to code lines in one day :)
i select category1 category2 and category3 with select code but i have just one index.. it is productnumber and it is primarykey..So my select code lines is so slow.. it is 7-9 second.. how can i select in 0.1 second ? Should i create index for category1 and category2 and category3 ? But i dont know create index.. My select code lines is below.. Could you learn me and show me index for it ?? or Could you learn me and show me fast Select code lines and index or etc ??? Also my search code line have a dangerous releated to attaching table1 with hackers :)
cheersi send 3 value of treview1 node and childnode and child.childnode to below page.aspx :)
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If Not Me.IsPostBack Then
If Request("TextBox1") IsNot Nothing ThenTextBox1.Text = Request("TextBox1")
End If
If Request("TextBox2") IsNot Nothing ThenTextBox2.Text = Request("TextBox2")
End If
If Request("TextBox3") IsNot Nothing ThenTextBox3.Text = Request("TextBox3")
End If
End If
Dim searchword As String
If Request("TextBox3") = "" And Request("TextBox2") = "" Then
searchword = "Select * from urunlistesi where kategori= '" & Request("TextBox1") & "'"
End If
If Request("TextBox3") = "" Then
searchword = "Select * from urunlistesi where kategori= '" & Request("TextBox1") & "' and kategori1= '" & Request("TextBox2") & "'"
End If
If Request("TextBox3") <> "" And Request("TextBox2") <> "" And Request("TextBox1") <> "" Then
searchword = "Select * from urunlistesi where kategori= '" & Request("TextBox1") & "' and kategori1= '" & Request("TextBox2") & "' and kategori2= '" & Request("TextBox3") & "'"
End If
SqlDataSource1.SelectCommand = searchword
End Sub
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Jul 9, 2004
Hi,
I'm running a merge replication on a sql2k machine to 6 sql2k subscribers.
Since a few day's only one of the merge agents fail's with the following error:
The merge process could not retrieve generation information at the 'Subscriber'.
The index entry for row ID was not found in index ID 3, of table 357576312, in database 'PBB006'.
All DBCC CHECKDB command's return 0 errors :confused:
I'm not sure if the table that's referred to in the message is on the distribution side or the subscribers side? A select * from sysobjects where id=357576312 gives different results on both sides . .
Any ideas as to what is causing this error?
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Jul 3, 2006
Hi everyone,
When we create a clustered index firstly, and then is it advantageous to create another index which is nonclustered ??
In my opinion, yes it is. Because, since we use clustered index first, our rows are sorted and so while using nonclustered index on this data file, finding adress of the record on this sorted data is really easier than finding adress of the record on unsorted data, is not it ??
Thanks
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