I had an existing table with lots of indexes.
As a test (fro speed) - I added a non clustered column-store index.
When I run test queries it always ignores my new column-store index. Why?
Should I remove the old indexes, leaving just the column store?
I am checking some ratio numbers for our system engineers, those are
Read/write ratio?
Random/sequential ratio?
Read/write block size?
For Read/write ratio, I am using below query,
SELECT
m.type_desc
, CEILING(sum(num_of_bytes_read*1.0) / (sum(num_of_bytes_read*1.0) + sum(num_of_bytes_written*1.0)) * 100) AS 'Read %'
, CAST((sum(v.size_on_disk_bytes) / 1024.0 / 1024 / 1024) AS MONEY) AS 'FileSizeGB'
[Code] ....
Random/sequential ratio, I googled but cannot find a similar query to get the result?
I am writing a performance baseline test.
The first test writes 5000000 rows in one table. I realise this is not representative OLTP behaviour, but it worked me to start interpreting performance counters and to test several setups to be discussed with our server, storage and network administrators. This way we have been able to compare the results of different hard disks, Lun vs vmdk, 1GB vs 10GB network, AMD vs Intel, etc. This way I can also compare several SQL setups (recovery model, max memory config, ...)
The screenshot shows the results of 2 runs on the same server : Win2012R2, SQL2014, 16GB RAM.
In test 1 min/max server memory was set to 9215MB/10751MB
In test 2 min/max server memory was set to 13311MB/14847MB
The script assures the number of bytes inserted in the nvarchar columns is always the same.
This explains why the number of pages and the number of MB in the table are the same at the end of the 2 tests (column 5 and 6)
Since ca 13GB has to be written, the results of test 1 show the lead time is increasing once more than 10GB has been inserted (column 8 and 9) In addition you can see at that moment
- buffer cache hit ratio is decreasing
- page life expectance becomes "terrible"
- free list stall/sec increases
- lazy writes/sec increases
- readlatency increases (write latency does not)
In test 2 (id 3 in column 1 in the screenshot) those counters are not really influenced (since the 5000000 rows can all be stored in memory).
Now what I do not understand is :
Why the number of pages read (instance level) as well as the number of bytes read and the number of reads (databaselevel) is increasing extremely during run 1.
I expected to see serious impact on write behavior, since SQL server is forced to start flushing dirty pages once memory is filled. Well actually you can see here the number of writes (not the the number of bytes written) starts to increase faster in test 1 after 4000000 rows, but there's no real impact on write latency.
Finally I want to notice
- I'm the only user on this machine
- the table has a clustered index on a identity column
- there are no foreign key constraints
- inserts are executed using a loop, not one big transaction
- to monitor progress and behaviour/impact, each 10.000 loops the counters are stored using dmv queries
So I wonder why SQL Server starts to execute so many reads in test 1.
I Want to test for Automatic switch between primary and secondary.
How do i do it ?
or
I need this for some purpose : How to set suspect mode for a database ?
how to take backup of indexes for a particular table.
View 1 Replies View RelatedHow to take backup of indexes for a particular table.
View 5 Replies View RelatedI have inherited a database that is over-indexed, i.e. there are sometimes 10-20 indexes on a table. The performance is at times not great due to blocking from long running queries. I want to clean up the indexes as a starting point.
Through a query I found some time ago on the SQLCat blog I have discovered a large number of indexes in the database that have a huge disparity between reads and writes. The range of difference is sometimes almost 2 million more writes than reads. Should I just drop the indexes that have say, more than 100,000 more writes than reads and then see what the Missing Index DMVs tell me after a few days of running without those indexes?
In some cases there are a few hundred thousand reads but maybe a million writes on the index. Thus, there are a fair number of reads happening, just not in comparison to the number of writes. In some cases there are almost no reads and a million or more writes. I am obviously dropping those indexes. I just am not sure what to do about the indexes that do have a fair number of reads.
Do I need to rebuild my indexes on my High Availability listeners?
When I do a full index rebuild on my primary DB's. Does rebuilding also send the rebuild to the listener(s)?
I am trying to write a sql script that will basically test logins for Windows NT Similar to when you bring up SQL Studio, and do run as windows NT I want to ensure my rights are not removed from SQL Servers and if so send my nice DBA an email.
How to do the connect as ? and check my permission is still set to access database with db_datawriter, db_datareader etc
I've been trying to get a definitive answer to this question but alas I have conflicting and patchy answers so far from other sources. I have an index that, lets say, requires 10GB of data space to rebuild..This index resides on a filegroup that spans 2 files on two seperate drives (i.e. a mdf and ndf)
When I rebuild this index how will each of these datafiles grow as the rebuild proceeds to completion? Lets for the time being remove the caveats of any other activity hitting the example index/database in question.My tests seem to show that only the mdf will grows (or the file with the lowest id in the that filegroup) provided there is enough space available in that particular file to complete the operation. The secondary ndf dat file doesnt grow at all if the mdf has enough space.
Is expected behavior? i.e. the index will be rebuilt in a contiguous manner relative to the files contained with the filegroup i.e. fileid 1 will grow till limit reached then next fileid grows etc?
I am new in SQL Server, What to check ,what action do i need to take while adding a new column to a table.
View 5 Replies View RelatedI have a database it is 50 gb with hundreds of columns. I would like to choose a certain column and convert the data in it to .csv or excel file. How can I do that I am very new to MSSQL...
View 1 Replies View RelatedI would like to put a Clustered Index on a date column in a current heap, but one question/concern.This heap every month has thousands of rows deleted and even more added later. How much of an issue will this cause the Clustered Index as far as page splits? I was thinking Fill Factor of 70%.I would normally just test and still will on Dev box, but my Dev box is much smaller than production as far as power.
View 6 Replies View RelatedI need to encrypt some column level data in multiple tables in SQL server 2014. I've never tried encryption in SQL server 2014. How can I achieve it?
View 4 Replies View RelatedI am trying to implement the column encryption on one of the tables, have used the below link as the reference and got stuck at the last step.
[URL] ....
I have completed the following steps so far.
- CREATE MASTER KEY ENCRYPTION BY PASSWORD = ‘myStrongPassword’
- CREATE CERTIFICATE MyCertificateName
WITH SUBJECT = 'A label for this certificate'
- CREATE SYMMETRIC KEY MySymmetricKeyName WITH
IDENTITY_VALUE = 'a fairly secure name',
ALGORITHM = AES_256,
[Code] .....
Example by using the function
EXEC OpenKeys
-- Encrypting
SELECT Encrypt(myColumn) FROM myTable
-- Decrypting
SELECT Decrypt(myColumn) FROM myTable
When I ran the last command :
-- Decrypting
SELECT Decrypt(myColumn) FROM myTable
I get the following error :
Msg 257, Level 16, State 3, Line 2
Implicit conversion from data type nvarchar to varbinary is not allowed. Use the CONVERT function to run this query.
Where will I use the convert function, in decrypt function or in select statement?
I have created a stored procedure for retrieving column name, as shown below
CM_id, CM_Name, [Transaction_Month], [Transaction_Year], [Invoice raised date],[Payment Received date],[Payout date],[Payroll lock date]
Now I am trying to create a temporary table using the above generated coluimns from Stored Procedure with datatype.
SQL server, by-mistake I updated values of a column in a database hosted online, is there any way undo the transaction. I didn't created any backup of the database. I read that still it can be recovered through the .ldf (log file) but unable to access it. Is there anyway to get access of the Log file or is there any way to recover the data.
View 1 Replies View RelatedID A B C AVG
------------------------
1 08 09 10 -
------------------------
2 10 25 26 -
------------------------
3 09 15 16 -
------------------------
I want to calculate the average of the larges two number from the column A,B & C for particular identity and store that average in the AVG column....
I have two inline selects against a table with a nonclustered columnstore on SQL 2014 (12.0.2000). Both execute in batch mode and when I inner-join the two, they continue to execute in batch mode. When I cross join them, one executes in row mode. Below is some SQL to simulate the issue.
-- The purpose of this script is to demonstrate that
-- two queries against a columnstore index that each execute in batch mode
-- will continue to execute in batch mode when inner joined.
-- However, one of the queries will execute in row mode when cross-joined.
-- Create function to return 0 to n rows
IF OBJECT_ID('dbo.IntCount') IS NOT NULL
DROP FUNCTION dbo.IntCount;
[Code] .....
I am trying to use an indexed view to allow for aggregations to be generated more quickly in my test data warehouse. The Fact Table I am creating the indexed view on is a partitioned clustered columnstore index.
I have created a view with the following code:
ALTER view dbo.FactView
with schemabinding
as
select local_date_key, meter_key, unit_key, read_type_key, sum(isnull(read_value,0)) as [s_read_value], sum(isnull(cost,0)) as [s_cost]
, sum(isnull(easy_target_value,0)) as [s_easy_target_value], sum(isnull(hard_target_value,0)) as [s_hard_target_value]
, sum(isnull(read_value,0)) as [a_read_value], sum(isnull(temperature,0)) as [a_temp], sum(isnull(co2,0)) as [s_co2]
, sum(isnull(easy_target_co2,0)) as [s_easy_target_co2]
, sum(isnull(hard_target_co2,0)) as [s_hard_target_co2], sum(isnull(temp1,0)) as [a_temp1], sum(isnull(temp2,0)) as [a_temp2]
, sum(isnull(volume,0)) as [s_volume], count_big(*) as [freq]
from dbo.FactConsumptionPart
group by local_date_key, read_type_key, meter_key, unit_key
I then created an index on the view as follows:
create unique clustered index IDX_FV on factview (local_date_key, read_type_key, meter_key, unit_key)
I then followed this up by running some large calculations that required use of the aggregation functionality on the main fact table, grouping by the clustered index columns and only returning averages and sums that are available in the view, but it still uses the underlying table to perform the aggregations, rather than the view I have created. Running an equivalent query on the view, then it takes 75% less time to query the indexed view directly, to using the fact table. I think the expected behaviour was that in SQL Server Enterprise or Developer edition (I am using developer edition), then the fact table should have used the indexed view. what I might be missing, for the query not to be using the indexed view?
I want to set up a database role so that users can use sp_readerrorlog through SSMS. It does a check on membership in the securityadmin role.
I have tested it and can see you can grant execute on xp_readerrorlog but the SSMS GUI uses sp_readerrorlog.
I thought I could create a user/certificate and add the signature to sp_readerrorlog but it's not permitted (likely because it's not a normal database object).
So the other solution is to add the users to the securityadmin role but then explicitly deny alter any login (best done with a custom server role in 2012+ but otherwise just manually in 2008). I tested this out and it works, I'm not able to alter any logins or increase my own permissions, I also did a check of what's reported from fn_my_permissions(null, null) and it shows minimal permissions like I'd expect.
I've been asked to look at using Clustered Columnstore indexes for one of my tables. The table contains about 5 million records with about 50 columns. The max field size is a NVarchar(MAX) with max field length currently of about 4k characters. It's only about a gigabyte's worth of data. The table is about 50% R/W operations. Currently, we have multiple indexes with no clustered index due to some performance issues that happened in the past. I've been attempting to determine if it's even really worth it to switch over. I feel that the table is still fairly small with minimal columns and don't believe there will be any noticeable improvement over traditional indexing.
View 3 Replies View RelatedI have a database in which I have some tables in which I have implemented Clustered columnstore Index. How to find the fragmentation levels of all these indexes via a single T-SQl script
View 3 Replies View RelatedHow can we get the list of clustered columnstore index in a database in sql server 2014
View 3 Replies View RelatedI wonder whether there's documentation about inline syntax for indexes for SQL Server 2014?
CREATE TABLE Consumer
(
Account nvarchar(20) null,
Consumption float null,
INDEX IX_Consumer_Account NONCLUSTURED (Account)
);
I'm just beginning to experiment with memory optimised tables.
I have two sets of near identical tables - one set normal, the other set memory optimised with DURABILITY=SCHEMA_ONLY - and am running test queries against these. When I say that the two sets are "near identical", I mean that they are the same except for the primary keys: for the normal tables these are defined as PRIMARY KEY CLUSTERED whereas for the memory-optimed ones they are defined as PRIMARY KEY NONCLUSTERED HASH WITH (BUCKET_COUNT=nnnn) as per the requirements for such tables.
I then run a pair of test queries, again identical but one referencing the normal tables and the other referencing the memory optimised ones.
(The query uses an inner join on three tables with row counts of approx 3m rows, 100000 rows and 5000 rows.)
The query against the normal tables runs noticeably faster than that against the memory optimised ones. To try to find out why, I examined the execution plans. the plan for the memory optimised query suggests that I have a missing index: but of course I can't create this againsty a memory optimised table. Is this a bug or am I missing something? Why the performance between the two should be so different?
I inherited a lot of Servers to upgrade to 2014 to include an SSRS Server.
The encryption Key was never backed up and it seems that no one knows what the password is?
Do I have to manually load the reports? There are a lot of Reports.
[URL]
I want to use BCP to load data from a text file.
By default, constraints are turned off in bcp, so I use the CHECK_CONSTRAINTS hint.
bcp aborts if ANY of the rows contains a FK violation. No data get loaded.
So if I add the -b 1 batch size option, it loads all data UNTIL the first FK violation, but nothing after that.
I want to load EVERYTHING ... except for the violations. But bcp won't let me. Is there a way?
If I install an instance with Windows Only authentication, and then change it to Mixed Mode, if I enable the sa login, the password has already been set. What is the default? If it's generated, how secure is it? Is the password generated? What algorithm is used for that?
View 9 Replies View RelatedMy sql databases in SQL Server 2014 has the status "suspend" as I saw in SQL Management Studio. I can't restore to serviceable condition sql databases through standard procedures. I need to restore .mdf file.
View 9 Replies View RelatedI am using a monitoring system where I can monitor a numeric SQL result assuming the result is one field and one row.I would like to do this to say monitor the free available space or percentage on say the Master database. DBCC SQLPERF gives me a few columns and results for all databases on the server.
View 2 Replies View RelatedIn our environment applications are using a DNS name which points to the physical server ip address. Now we are planning to move to 2014. We are planning to have servers in different subnets so we will be having two ip adresses for listener. How we can point the DNS to the listener ips? If failover happens can the DNS point to the exact ip address of the listener where it's primary node?
View 1 Replies View RelatedIs there a way to schedule a sql job to run at different intervals
For eg:
The job should run at
7:00 Am
8:00 AM
and then at 10:00 Am