MS SQL Collation Issues

Fixing MS SQL Collation Differences

By Strictly-Software

With the quiet due to the COVID19 virus scare, and all major sporting events being cancelled for the foreseen future, I decided now would be a good time to get my old Automatic Betting BOT back up and working.

It used to run on a dedicated Windows 2003 server and MS SQL 2012 database before being outsourced to a French hosting company, OVH, which doesn't allow HTTP connections to online betting sites, basically making it useless. A decision that wasn't mine in anyway, but basically stopped my BOT from working.

It used to run as a Windows Service using Betfair's Exchange API to automatically create betting systems and then place bets based on systems with a rolling ROI > 5% over the last 30 and 100 days.

I am trying to get the BOT working on a local laptop and therefore it had already been backed up, the files FTP'd down to my laptop and restored in a local MS SQL Express database. 

However it seems that I had some issues when I previously attempted this some time ago as the database now had a different collation, a number of tables were now empty and had been scripted across without indexes and there was a collation difference between many columns and the new DB collation.

Just changing the Databases collation over isn't a simple act on it's own if numerous table column collations are different as well, especially those used in Indexes or Primary Keys as those references need to be removed before the collation can be changed.

A simple fix when it's only a small issue with one column might be to just edit the SQL where the issue arises and use a COLLATE statement so that any WHERE clause or JOIN uses the same collation e.g

SELECT  MemberID, MemberName
FROM MEMBERS 
WHERE MemberName COLLATE SQL_Latin1_General_CP1_CI_AI = @Name

However when you have a large database and the issue is that half your tables are one collation, the other another, and you need to decide which to move to, and then it becomes more difficult.

My new Database was using the newer SQL_Latin1_General_CP1_CI_AI collation whilst a subset of the tables were still using the older collation from the servers copy of the database Latin1_General_CI_AS.

Therefore finding out which columns and tables were using this collation was the first task and can easily be done with a system view with some SQL like so:

-- find out table name and columns using the collation Latin1_General_CI_AS
SELECT table_name, column_name, collation_name
FROM information_schema.columns
WHERE collation_name = 'Latin1_General_CI_AS'
ORDER BY table_name, column_name

From this I could see that the majority of my tables were using the older collation Latin1_General_CI_AS and that it would be easier to change the database collation to this, then the table collation.

However as there were very few indexes or keys I decided to do the reverse and use the newer collation SQL_Latin1_General_CP1_CI_AI, and change all columns using the LATIN to this new version.

However as I want to show you what to do if you need to change your MS SQL database and columns over to a new collation just imagine I am doing the opposite e.g I am changing my whole system from SQL_Latin1_General_CP1_CI_AI to Latin1_General_CI_AS.

If you did want to change the database collation after it had been created it is not as simple as just opening the databases property window and selecting a new collation OR just running the following query to ALTER the database. Just read the error message I was getting when attempting this.

USE master;
GO

ALTER DATABASE MyDatabase
COLLATE Latin1_General_CI_AS ;
GO

Msg 5030, Level 16, State 5, Line 18
The database could not be exclusively locked to perform the operation.

Msg 5072, Level 16, State 1, Line 18
ALTER DATABASE failed. The default collation of database 'MyDatabase' cannot be set to Latin1_General_CI_AS.

Apparently this locking issue is due to the fact that SSMS opens a second connection for Intellisense.

Therefore the correct way to do this, even if you are the only person using the database, as I was, is to put it into single user mode, carry out the ALTER statement, then put it back in multi user mode. #

This query does that.

ALTER DATABASE MYDATABASE SET SINGLE_USER WITH ROLLBACK IMMEDIATE

ALTER DATABASE MYDATABASE COLLATE Latin1_General_CI_AS 

ALTER DATABASE MYDATABASE  SET MULTI_USER

Once the database has been changed to the right collation you will need to change all the tables with columns using the differing collation. However any columns being used in Indexes or Keys will need to have their references removed first. Luckily for me I didn't have many indexes at this point.

However I still needed to script out any Indexes and Key Constraints I had and save them into an SQL file so that they could easily be re-created afterwards.

I then dropped all the Indexes and Keys that needed to be removed and then ran the following piece of SQL which outputs a load of ALTER TABLE statements.

You may find like I did, that you actually need to add a COLLATE statement into the WHERE clause to get it to work without erroring as the system tables themselves may have a different collation than the one you are wanting to search for.

SELECT 'ALTER TABLE ' + quotename(s.name) + '.' + quotename(o.name) + 
       ' ALTER COLUMN ' + quotename(c.name) + ' ' + type_name(c.system_type_id) 
    +CASE  
   WHEN c.max_length = -1 THEN '(max)'
   WHEN type_name(c.system_type_id)  = 'nvarchar' THEN '('+CONVERT(varchar(5),c.max_length/2)+')'
   ELSE '('+CONVERT(varchar(5),c.max_length)+')'   
  END + CASE WHEN c.[precision] = 0 THEN ' COLLATE '+c.collation_name   + ' ' ELSE ' ' END + LTRIM(IIF(c.is_nullable = 1, '', 'NOT ') + 'NULL ' )
FROM  sys.objects o
JOIN  sys.columns c ON o.object_id = c.object_id
JOIN  sys.schemas s ON o.schema_id = s.schema_id
WHERE o.type = 'U' 
  AND c.collation_name <> 'Latin1_General_CP1_CI_AI' -- the collation you want to change from
ORDER BY o.[name]

You should get a load of SQL statements that can be run in a new query window to change all your columns.

It is best to run the previous SQL outputting to a textual window so that the output can easily be copied and pasted.

ALTER TABLE [dbo].[TRAINER_PERFORMANCE] ALTER COLUMN [RatingType] varchar(20) COLLATE Latin1_General_CI_AS
ALTER TABLE [dbo].[CANCEL_KILLED] ALTER COLUMN [RecordDetails] nvarchar(max) COLLATE Latin1_General_CI_AS

Once you have run all these ALTER statements your whole database should be the collation that you require.

You can then take your copy of the Indexes and Keys that you created earlier, and run them to recreate any missing Indexes and Constraints. You should then be able to remove any quick fix WHERE clauses COLLATE statements that you may have used as a quick fix.

Collation differences are a right pain to resolve but if you do everything in order, and keep saved records of ALTER and CREATE statements that you need along the way it can be something fixed without too much work.

There are some large scripts to automate the process of dropping and re-creating objects if you want to use them however I cannot test to the reliability of these as I chose to do everything bit by bit, checking and researching along the way.

By Strictly-Software

Rebuilding a Stored Procedure From System Tables MS SQL

Rebuilding a Stored Procedure From System Tables MS SQL

By Strictly-Software

Quite often I find "corrupted" stored procedures or functions in MS SQL that cannot be opened in the visual editor.

The usual error is "Script failed for StoredProcedure [name of proc] (Microsoft.SqlServer.Smo)"

This can be due to comments in the header of the stored procedure that confuse the IDE or other issues that you may not be aware of.

However if you get this problem you need to rebuild the stored procedure or function ASAP if you want to be able to edit it visually again in the IDE.

The code to do this is pretty simple and uses the sys.syscomments table which holds all the text for user-defined objects. We join on to sys.sysobjects so that we can reference our object by it's name.

When you run this with the output as "Results To Grid" you may only get 1-4+ rows returned and the data isn't formatted usefully for you to just copy and paste and rebuild.

Therefore always ensure you chose "Results To Text" when you run this code.

Make sure to change the stored procedure name from "usp_sql_my_proc" to the name of the function of stored procedure you need to rebuild!

SELECT com.text
FROM sys.syscomments as com
JOIN sys.sysobjects as sys
 ON com.id = sys.id
WHERE sys.name='usp_sql_my_proc'
ORDER BY colid

SQL 2012 Bug - Incorrect Syntax Need BEGIN Statements

SQL 2012 Bug - Incorrect Syntax Need BEGIN Statements

We recently moved Database servers from 2008 to 2012.

Everything seemed to have gone fine until we found that one of our logger database tables had grown to a massive size holding millions of rows and containing many more days records than it should have.

As this was over the Christmas period no-one really noticed until we got back from holiday.However a look in the log files from the MS Agent job showed that the part of the Stored Procedure to delete old records was failing and then the proc was bombing out, which meant none of the older historical records were being deleted.

The error message in the log file was "Incorrect Syntax near begi" and then just a load of failed statements.

There are some Microsoft knowledge base articles about this issue that say the problem is due to:

• The statement contains an IF condition.
• The IF condition does not contain BEGIN and END statements.
• The IF condition is followed by a BEGIN TRY block.
• The IF block is recompiled when you run the query. 

You can read more about the problem on Microsofts own sites:

https://connect.microsoft.com/SQLServer/feedback/details/752276/incorrect-syntax-near-begi-in-sql-2012

and

http://support.microsoft.com/kb/2829372

They actually provide this example code which is supposed to replicate the error in MS SQL 2012 however when I ran it in a query window it worked fine for me.

DECLARE @i INT

IF object_id('tempdb..#temptable') IS NOT NULL
DROP TABLE #temptable

CREATE TABLE #temptable (id INT)
INSERT INTO #temptable VALUES (1),(2),(3);

IF year(getdate())=2012 SELECT @i=(SELECT COUNT(*) AS nr FROM #temptable);
BEGIN TRY
SELECT 'message'
END TRY

BEGIN CATCH
SELECT ERROR_MESSAGE()
END CATCH

Therefore I then thought that maybe the problem might not be the actual language and queries but something to do with Stored Procedures CONTAINING such language.

The stored procedures that were bombing out were full of statements that had IF statements near BEGIN TRY without an END before it. For example we put in DEBUG statements for logging and being able to debug the code after the midnight hours so we would have code like this all over the place.

DECLARE @i INT

IF @DEBUG = 1
  PRINT 'About to run code to delete old historical records'

BEGIN TRY
  ...code
END TRY
BEGIN CATCH
 .. code
END CATCH

As our DBA didn't want to install a "dodgy" hotfix as he called it, even though SP1 had been installed (which didn't fix the issue) to test this theory out we made sure any of our IF statements were wrapped in BEGIN ..code... END statements like this.

DECLARE @i INT

IF @DEBUG = 1
  BEGIN
       PRINT 'About to run code to delete old historical records'
  END

BEGIN TRY
  ...code
END TRY
BEGIN CATCH
 .. code
END CATCH

So we put the new code into our proc and let it run that night from MS Agent.

Guess what?

When we ran the MS Agent job that night that fired off these stored procedures the whole thing worked!

I don't know if it is necessarily a stored procedure problem or not but this simple fix for our own code seemed to solve the problem without having to apply the hotfix so it seemed to solve the problem for us.

How Microsoft have gotten so far into their roll out of SQL 2012 with such a problem in their code I have no idea but it seems to be such an annoying bug that a lot of people are complaining about it.

Hopefully this solution may fix it all for you as well!

Shrinking an MS SQL Database MDF file after a TRUNCATE or big DELETE

Shrinking an MS SQL Database MDF file after a TRUNCATE or big DELETE

I am not a DBA and we don't have a dedicated one at our company therefore when I had a database file with a huge table containing 80 million rows of data taking up 35 GB I needed to remove it.

I re-planned my usage of the table and decided that it would only keep a days worth of data instead of every day (going back 3 years) and re-jigged some code about.

I then set up an nightly job with a TRUNCATE TABLE statement to remove the data quickly at midnight each day.

However just by doing this alone does not reduce the size of the database file (MDF) and you will have reserved and unused space that you may want to reclaim or get rid of.

The current sizes of the database file before running any clean ups was 35 GB and as I was using simple mode for the transaction log the size of that file was negligible. Therefore after much research I had to go through the following routine to reduce the size of the database file.

A lot of people will warn you not to Shrink a database file as it will only grow again and cause disk fragmentation which is correct however if you have just removed a large table like I have then this is one case where a DBCC SHRINKFILE command is useful.

Therefore this is the approach I followed this morning.

I first ran this SQL to find out current size of tables and indexes plus any reserved and unused space within each database table. I also list out the tables in order of reserved size to see which has the most to be reclaimed and whether or not it matched the table I thought was causing problems - which it did.

CREATE TABLE #t (name SYSNAME, rows CHAR(11), reserved VARCHAR(18), 
data VARCHAR(18), index_size VARCHAR(18), unused VARCHAR(18))

DECLARE @Sizes TABLE(name SYSNAME, rows int, reserved int, Data int, index_size int, unused int)

-- ensure correct values are being returned by using  @updateusage see http://msdn.microsoft.com/en-us/library/ms188776.aspx
EXEC sp_msforeachtable 'INSERT INTO #t EXEC sp_spaceused ''?'', @updateusage = N''TRUE'';'

INSERT INTO @Sizes
SELECT Name, Rows, CAST(SUBSTRING(Data, 1, LEN(Data)-3) as INT), CAST(SUBSTRING(Reserved, 1, LEN(Reserved)-3) as INT),
  CAST(SUBSTRING(Index_Size, 1, LEN(Index_Size)-3) as INT), CAST(SUBSTRING(Unused, 1, LEN(Unused)-3) as INT)
FROM #t

DROP TABLE #t

SELECT CAST(SUM(Data) as varchar)+' KB' as 'Data Size',
  CAST(SUM(Reserved) as varchar)+' KB' as 'Reserved Size',
  CAST(SUM(Index_Size) as varchar)+' KB' as 'Index Size',
  CAST(SUM(Unused) as varchar)+' KB' as 'Unused Size'
FROM @Sizes


SELECT *
FROM @Sizes
ORDER BY Reserved DESC

Then I ran this script that I found to find out if there is space that can be removed.

SELECT name ,size/128.0 - CAST(FILEPROPERTY(name, 'SpaceUsed') AS int)/128.0 AS AvailableSpaceInMB
FROM sys.database_files;

This showed me that there was indeed a good 30 GB or so that could be removed.

Once I had worked out the new size of the data file in megabytes that I wanted to reduce the MDF file of my database to I ceased all activity on the database to help speed up the process and prevent any errors.

I then ran the following command: DBCC SHRINKFILE (details here)

To find the logical file name that you need to shrink either an MDF (database) or LDF (log file) run this command.

sp_helpdb [database name]

Once everything was ready I ran the following command to shrink a database to 6 GB (you have to pass the value in as MB) which left some room for the database to grow into.

DBCC SHRINKFILE([database name], 6144);

After running the command I did not see an immediate difference when I checked the properties of the database in MS Management Studio.

Therefore I ran a job to ReIndex my tables and rebuild rebuild statistics.

If you don't already have a nightly/weekly MS Agent job set up to do this for you then the following script of mine might be useful for you: ReIndex or ReOrganize your MS SQL indexes.

This script will allow you to set a percentage e.g 30% and if the index is fragmented over that percentage then a full REBUILD of the Index is carried out otherwise a REORGANIZE is performed.

After the rebuilding is done a call to EXEC sp_updatestats is made to update the systems statistics.

If you are going to use this SQL code check that the parameters within the stored procedure are to your liking and turn the DEBUG flag on if you require it.

The script will show you the fragmentation level before and after the script has run so that you can see how much difference it has made.

I found that after doing this when I went to database > properties > files I could now see the new sizes.

Logical Name
File Type
Filegroup
Initial Size
Autogrowth
Path
File Name




MyDB
Rows Data
PRIMARY
6144
By 1 MB, unrestricted growth
C:\Program Files 9x86)\Microsoft SQL Server\MSSQL.1\MSSQL\DATA
MyDB.mdf


MyDB_log
Log
Not Applicable
7377
By 10 Percent, restricted growth
C:\Program Files 9x86)\Microsoft SQL Server\MSSQL.1\MSSQL\Data_logs
MyDB_log.ldf

This clearly shows that my database MDF file has been reduced from 35 GB to 6 GB.

If anyone else has any comments or notes on best practise I would be glad to hear them.

Another MySQL Tuning Tool

MySQL Configuration and Tuning

One thing I really don't like about MySQL compared to MS SQL is the number of configurable options and the lack of data management  views to help you diagnose performance issues. Yes there are tools available but I haven not come across anything as good as the Activity Monitor for an overview of your servers performance in MySQL.

Being able to quickly see the primary cause of performance issues in graph form, high CPU, memory, I/O, blocking, the processes causing the blocking and those effected by the blocks, performance intensive queries and so on in a visual format is very useful.

Another great thing about MS SQL is the amount of Data Management Views and the reports you can create to find the most expensive queries, those with missing indexes, those that require tuning or index rebuilding, query plan re-use or under-user etc are all very useful tools.

Therefore when I come across anything that is semi useful for performance tuning MySQL I will make a note of it and list it on this blog so that other Microsoft developers using LAMP, WAMP etc can benefit from them as well.

One tool I came across tonight which has gone into my rackspace server alongside other MySQL configuration analysers is the MySQL Performance Tuning Primer Script which along with others of a similar ilk will analyse your database settings from a SHOW /*!50000 GLOBAL */ STATUS command and then make recommendations that you can use in your MySQL.cnf file.

To install this script you will need to do the following.

1. Open a SSH console window up.
2. Move to the right folder e.g cd /usr/local/src/
3. Use WGet to load the file to your server e.g wget http://day32.com/MySQL/tuning-primer.sh
4. Grant execute permission to the script e.g chmod u+x tuning-primer.sh
5. Try running the script e.g ./tuning-primer.sh

You might get an error like I did on the first attempt which said:

Error: Command line calculator 'bc' not found!

If you don't know bc is (which I didn't) it is the command line arbitrary precision calculator from GNU and it is obviously used within the shell script we are trying to run.

Therefore you will need to install this as well by using apt-get. So run this:

apt-get install bc

Which will install the bc app.

Now try again e.g

/usr/local/src# ./tuning-primer.sh

And you should get something like this:

Using login values from ~/.my.cnf
- INITIAL LOGIN ATTEMPT FAILED -
Testing for stored webmin passwords:
Could not auto detect login info!
Found potential sockets: /var/run/mysqld/mysqld.sock
Using: /var/run/mysqld/mysqld.sock
Would you like to provide a different socket?: [y/N] n
Do you have your login handy ? [y/N] : y
User: [enter your username e.g root or the password for the DB in question]
Password: [enter your password]

You will then get a report like the following and the option to create a new MySQL configuration file if you require it.


Would you like me to create a ~/.my.cnf file for you? [y/N] : n


-- MYSQL PERFORMANCE TUNING PRIMER --
- By: Matthew Montgomery -

MySQL Version 5.0.51a-24+lenny5-log x86_64

Uptime = 7 days 23 hrs 32 min 26 sec
Avg. qps = 10
Total Questions = 7286512
Threads Connected = 1

Server has been running for over 48hrs.
It should be safe to follow these recommendations

To find out more information on how each of these
runtime variables effects performance visit:
http://dev.mysql.com/doc/refman/5.0/en/server-system-variables.html
Visit http://www.mysql.com/products/enterprise/advisors.html
for info about MySQL's Enterprise Monitoring and Advisory Service

SLOW QUERIES
The slow query log is enabled.
Current long_query_time = 2 sec.
You have 178496 out of 7286569 that take longer than 2 sec. to complete
Your long_query_time seems to be fine

BINARY UPDATE LOG
The binary update log is NOT enabled.
You will not be able to do point in time recovery
See http://dev.mysql.com/doc/refman/5.0/en/point-in-time-recovery.html

WORKER THREADS
Current thread_cache_size = 8
Current threads_cached = 7
Current threads_per_sec = 0
Historic threads_per_sec = 0
Your thread_cache_size is fine

MAX CONNECTIONS
Current max_connections = 100
Current threads_connected = 1
Historic max_used_connections = 15
The number of used connections is 15% of the configured maximum.
Your max_connections variable seems to be fine.

No InnoDB Support Enabled!

MEMORY USAGE
Max Memory Ever Allocated : 153 M
Configured Max Per-thread Buffers : 262 M
Configured Max Global Buffers : 114 M
Configured Max Memory Limit : 376 M
Physical Memory : 1.01 G
Max memory limit seem to be within acceptable norms

KEY BUFFER
Current MyISAM index space = 221 M
Current key_buffer_size = 64 M
Key cache miss rate is 1 : 3110
Key buffer free ratio = 14 %
You could increase key_buffer_size
It is safe to raise this up to 1/4 of total system memory;
assuming this is a dedicated database server.

QUERY CACHE
Query cache is enabled
Current query_cache_size = 40 M
Current query_cache_used = 20 M
Current query_cache_limit = 2 M
Current Query cache Memory fill ratio = 50.83 %
Current query_cache_min_res_unit = 4 K
MySQL won't cache query results that are larger than query_cache_limit in size

SORT OPERATIONS
Current sort_buffer_size = 2 M
Current read_rnd_buffer_size = 256 K
Sort buffer seems to be fine

JOINS
Current join_buffer_size = 132.00 K
You have had 89958 queries where a join could not use an index properly
You should enable "log-queries-not-using-indexes"
Then look for non indexed joins in the slow query log.
If you are unable to optimize your queries you may want to increase your join_buffer_size to accommodate larger joins in one pass.

Note! This script will still suggest raising the join_buffer_size when
ANY joins not using indexes are found.

OPEN FILES LIMIT
Current open_files_limit = 1024 files
The open_files_limit should typically be set to at least 2x-3x
that of table_cache if you have heavy MyISAM usage.
Your open_files_limit value seems to be fine

TABLE CACHE
Current table_cache value = 200 tables
You have a total of 146 tables
You have 200 open tables.
Current table_cache hit rate is 6%, while 100% of your table cache is in use
You should probably increase your table_cache

TEMP TABLES
Current max_heap_table_size = 200 M
Current tmp_table_size = 200 M
Of 985542 temp tables, 44% were created on disk
Perhaps you should increase your tmp_table_size and/or max_heap_table_size
to reduce the number of disk-based temporary tables
Note! BLOB and TEXT columns are not allow in memory tables.
If you are using these columns raising these values might not impact your ratio of on disk temp tables.

TABLE SCANS
Current read_buffer_size = 128 K
Current table scan ratio = 998 : 1
read_buffer_size seems to be fine

TABLE LOCKING
Current Lock Wait ratio = 1 : 1205
You may benefit from selective use of InnoDB.
If you have long running SELECT's against MyISAM tables and perform frequent updates consider setting 'low_priority_updates=1'
If you have a high concurrency of inserts on Dynamic row-length tables consider setting 'concurrent_insert=2'.

Then you can take the recommendations and change the MySQL configuration file yourself in /etc/mysql/my.cnf before restarting the MySQL server so that the changes take effect e.g.


/usr/local/src# /etc/init.d/mysql restart
Stopping MySQL database server: mysqld.
Starting MySQL database server: mysqld.
Checking for corrupt, not cleanly closed and upgrade needing tables..

Just another MySQL report in the same ilk as mysqltuner.pl and mysqlreport but still not as good as anything I have seen on MS SQL 2005-2008.