Welcome to my technical blog. I like data and databases they seem to be at the heart of everything, although my perspective may be a tad biased :).

Here I plan to jot down things that trip me up in work, along with things I find interesting. There will be no “level” to my posts, some will seem blindingly obvious. Hopefully others will be deeper and of more interest.

I enjoy rewriting SQL to improve performance. However its a double edged sword. As a complete re-write (rather than just refactoring the “slow bits”) often upsets the original author, as they loose all sense of ownership. So I save that for “legacy environments” 🙂

Below, I will mostly write in the first person (“… this worked for me” rather than “this may work for you if your environment is similar to mine”) in the hope that you can adapt my succinct notes that ACTUALLY WORKED to your situation.

Logins with no default database

This can happen when databases are dropped or renamed.

In Azure, cross database connections are disabled so its important to connect to the actual database you will be working on, rather than -say- master.

This will list all logins where the default database is missing:-

SELECT [name] Login,
       default_database_name MissingDefaultDB
FROM sys.server_principals
WHERE DATABASEPROPERTYEX(default_database_name, 'Status') IS NULL
AND default_database_name IS NOT NULL
ORDER BY [name];

Removing duplicates from a large table before adding a clustered primary key

The challenge with this one, was to remove over 2,000 duplicate rows from a 600,000,000 row heap, before a multi-column clustered primary key could be added.

(I am so happy to finally be able to document this, from a while ago. The phrase “uniquely challenging” was never so apt.)

My first idea was to create a empty copy of the source table, add a “ignore duplicates” index, then start an INSERT [dbo].[targettable] SELECT * FROM [dbo].[sourcetable]. However, I stopped after an hour as it was going to take too long.

My second idea was to use SSIS to populate the target-table. Again this was just too slow.

My third idea was to just remove the duplicates (2,000 being a much smaller number than 600,000,000). First though, a disclaimer, I only considered this ** high risk ** solution because the data was in a QA environment (not Live), and people were waiting for me.

Step one then, was to populate a temp-table with the duplicates …

SELECT column1, column2, column3, column4
INTO #tmp1
FROM [dbo].[sometablename]
GROUP BY column1, column2, column3, column4

(“column1” etc were not the real column names by-the-way 🙂 ). Step two was to loop through this list removing duplicates from the permanent table

WHILE exists (SELECT 1 FROM #tmp1)


		@1 = column1, 
		@2 = column2, 
		@3 = column3, 
		@4 = column4 
	FROM #tmp1

	FROM [dbo].[sometablename] 
	WHERE column1 = @1
	AND column2 = @2
	AND column3 = @3
	AND column4 = @4

	FROM #tmp1
	WHERE column1 = @1
	AND column2 = @2
	AND column3 = @3
	AND column4 = @4


Step three was to implement the clustered primary key. (by-the-way I was half expecting this to fail with a duplicates error, but happily the above loop had cleared a single duplicate from each pair, and thats all that was needed).

ALTER TABLE [dbo].[sometablename] 
ADD CONSTRAINT pk_sometablename
 ([column1], [column2], [column3], [column4]);

** just to point out – I consider the loop “high risk” because, an error message, a typo, accidentally running it twice, or faulty logic, could have resulted in disaster 🙂

Resource Governor

The Resource Governor is one of those rarely used tools, as its impact is inherently ‘negative’. It restricts resources from a user-group, but cannot be seen to boost performance of a more favoured group.

For example, you could restrict the SA login to use just 5% of the CPU resource. The effect of this would be that SA can use 100% of the CPU resource, until another user-group wants to use more CPU than is currently available. SA will then be throttled back, and back, until it is only using 5%. Five percent is the minimum SA can use.

It is not easy to see this throttling in action – without firing up perf-mon. Also, the GUI view within SSMS is not-so-good, showing only some of the configuration. Therefore this is one of those things that I work with completely at the code level.

So, here then is my crib-sheet …

-- ResPool.sql

-- 1 create custom resource pool of available hardware
USE master;

-- 2 create a group and link it to the resource pool
USE master;
USING MxResourcePool;

-- 3 populate the group
USE master;
CREATE FUNCTION dbo.fn_MxClassifier()
DECLARE @wg AS sysname
IF SUSER_NAME() = 'sa'
	SET @wg = 'MxWorkloadGroup'
	SET @wg = 'default'



-- check config

SELECT s.session_id,
s.login_name, WorkgroupAssignment, ResourcePoolAssignment

FROM sys.dm_exec_sessions s
JOIN sys.dm_resource_governor_workload_groups w
  ON s.group_id = w.group_id
JOIN sys.dm_resource_governor_resource_pools r
  ON w.pool_id = r.pool_id
WHERE s.host_name IS NOT NULL
ORDER BY nt_user_name-- s.session_id desc

-- undo

DROP FUNCTION dbo.fn_MxClassifier;

To sync a materialized view

To manually keep a results cache updated I recommend concatenating multi column primary keys rather than using full joins. If it looks simple it should last.

/* 1 Insert */

	[pkcomposite1] + [pkcomposite2]
		[pkcomposite1] + [pkcomposite2]

/* 2 Delete */

	[pkcomposite1] + [pkcomposite2]
		[pkcomposite1] + [pkcomposite2]

/* 3 Update */

	MAT.[somecolumn1] = VW.[somecolumn1],
	MAT.[somecolumn2] = VW.[somecolumn2]
	[mv].[sometablename] MAT
	[vw].[vw_someviewname] VW
	MAT.[pkcomposite1] + MAT.[pkcomposite2]
	VW.[pkcomposite1] + VW.[pkcomposite2]
	MAT.[somecolumn1] <> VW.[somecolumn1]
	MAT.[somecolumn1] <> VW.[somecolumn2];

Log shipping to SSRS

I like simplicity, and job schedules can add a ton of it. I set up one job on the primary server to backup logs, and one job on the secondary server to restore them from the primary share.

Both schedules were set to – every 15 minutes between 18:00 and 08:00 – so no overhead during the working day.

Incidentally, so I would never have to manually fix log shipping of a 2 TB database, I set up a 01:00 [full backup] job on the primary …

Which on completion would start a [full restore] job on the secondary (to “standby”)…

The first step of the [full backup] job was to check log shipping latency, and only proceed if it were over 2 hours.

Normally log shipping would run all night and the secondary server would be updated to 08:00. If there were an issue then the [full backup] / [full restore] jobs would “fix” log shipping and again the secondary would be updated to 08:00. If there were a more fundamental failure then the [full backup] / [full restore] jobs alone, would update the secondary to 01:00.

The final touches were to set the [full restore] job to notify me if it were ever executed, and to remove all notifications from the [log restore] job 🙂

Moving datafiles

Just so I can find this script when I need it …


USE master;

-- 1 alter the metadata to the new path

ALTER DATABASE [SomeDatabaseName] MODIFY FILE (NAME = SomeLogicalFileName, FILENAME = 'F:\SQLData\SomeFileName.mdf');

-- 2 take database offline


-- 3 move the datafile via windows explorer

-- 4 bring database online


Recovery Interval not optimal

The SQL Server “Recovery Time Interval” setting used to be ‘0’ by default, which could have a performance impact during a Checkpoint, by amplifying lazywriter contention.

Indirect checkpointing can alleviate this and has been available since SQL Server 2012. Indeed the default value was changed to ’60’ (seconds) from SQL Server 2016 onwards.

Splitting strings in practice.

Quite often on technical forums a request to extract part of a text string is tackled in splendid isolation. I’ve used the technique below with postcodes before, but this time wanted to split the text in an SSRS log file to isolate report names from paths.

For example the string …


… means the report called “Summary” is contained in the “Outgoing” folder within the “Monthly” folder inside the “Finance” folder in the root.

The tricky bit being that the nesting levels vary. There are reports in root. And there are reports buried ten layers deep like russian dolls.

Task one, getting the report names is relatively easy. You could use the REVERSE function to help grab the text up to the “first” slash using CHARINDEX.

Task two, getting the path, is where forums go deep, with strings of functions to extract all the text to the left of the last slash (where there are an unknown number of slashes).

Where as, it is often far simpler to use REPLACE to remove the already found report name from the whole string, leaving just the path.

       REPLACE(ItemPath,Report,'') [Path],
    SELECT RIGHT(ItemPath, CHARINDEX ('/', REVERSE(ItemPath))-1) Report,

Cannot drop user as it owns a schema

Whilst removing orphaned user accounts, I came across this error …

Msg 15138, Level 16, State 1, Line 1
The database principal owns a schema in the database, and cannot be dropped.

Looking at the properties of the user within the database I noticed that they owned the db_datawriter schema. Within the properties of that schema I was able to type db_datawriter as the new owner. After which I was able to remove the user from the database.

Here is a scripted way to do this …

Todays failed jobs

I cobbled this together to run on multiply servers via CMS. It is simpler and more trustworthy than alerts from monitoring-software.


    msdb.dbo.sysjobs AS J
        SELECT TOP(1)
            FailedAt = msdb.dbo.agent_datetime(T.run_date, T.run_time),
            Message = T.message
            msdb.dbo.sysjobhistory AS T
            T.job_id = J.job_id
			T.run_status = 0 -- failed
			msdb.dbo.agent_datetime(T.run_date, T.run_time) > getdate()-1 -- in the last 24 hrs
--			msdb.dbo.agent_datetime(T.run_date, T.run_time) > getdate()-3 -- covering the weekend
        ORDER BY
            T.instance_id) H

Original code from here …

Quick row count

When COUNT(*) was too slow to get total rows from a billion row heap …

       CONVERT(MONEY, rowcnt), 1), '.00', '')) [rows]
FROM sys.sysindexes
WHERE OBJECT_NAME(id) = 'TableName';

Original code from here …

Adding a database to an Azure backup policy

Twice I had to ask how to do this – so it is probably time for me to write it down.

Setting the scene – this was a virtual SQL Server hosted on Azure where I had already configured a backup policy within the Portal, and then wanted to add another database to that policy.

Clicking around in the Backup center and Backup policy screens did not help. The trick was to go through the motions of taking a backup.

  1. Within the Backup center click “+ Backup”

2. On the next screen make sure the Datasource type is “SQL in Azure VM” before selecting the right vault.

3. Choose “Configure Backup” …

4. Click “Add” …

5. Then – you can choose the Instance (or AlwaysOn AG), database, then Enable Backup. Simples 🙂

Removing Partitions

Remembering that indexes are partitioned not tables, I used this query to list them …

SELECT OBJECT_SCHEMA_NAME(i.object_id) AS [schema],
       OBJECT_NAME(i.object_id) AS [object], AS [index], AS [partition_scheme]
FROM sys.indexes i
JOIN sys.partition_schemes s
  ON i.data_space_id = s.data_space_id;

I found the quickest way to remove partitioning is :-

  • Make a copy of the partitioned table with all the data (EG: “tablename2”)
  • Recreate all indexes, keys, and constraints (specifying the “ON [PRIMARY]” option)
  • Drop the partitioned table
  • Rename the copy to the table that was just dropped
  • Drop any partition schemas and functions
SELECT * FROM sys.partition_schemes

SELECT * FROM sys.partition_functions

Replicating data from SQL Server to MySQL

Ok not really “Replication”. More like keeping a MySQL table in sync with a SQL Server table using both varieties of SQL.

I avoided using a linked-server as I wanted this to be able to cope with bulk loading. Sadly the correct tool, SSIS, was not available during this project.

I created a SQL Job with two steps 1) Export data to CSV and 2) Import into MySQL. The SQL code is highly parameterised so it can be reused.

Job Step 1: Export data to a CSV file

/* ExportDataToCsvFile.sql */

	DECLARE @datasource VARCHAR(100) = 'SomeTableName';
	SELECT @cmd = 'BCP SomeDatabase.dbo.' + @datasource + ' out D:\Export\' + @datasource + '.csv -t, -c -T';
	EXEC master..xp_cmdshell @cmd;

Line 1: Is just to let me know I have my own copy of this code block.
Line 3: Should be updated to the data source specific to each project (NOTE: For simplicity the data-source and CSV file both share this name.)

Job Step 2: Import CSV into MySQL table

/* ImportCsvIntoMYSqlTable.sql */

	DECLARE @table VARCHAR(100) = 'SomeTable'; /* << change this */
	DECLARE @database VARCHAR(100) = 'SomeInstance_SomeDatabase'; /* << change this */
	DECLARE @sql VARCHAR(2000) = '';
	DECLARE @cmd VARCHAR(8000);

/* 1 Build MySQL script to empty then refill table */

	SET @sql = @sql + 'START TRANSACTION;';
	SET @sql = @sql + 'DELETE FROM ' + @table + ';';
	SET @sql = @sql + 'LOAD DATA LOCAL INFILE ''G:\\Export\\' + @table + '.csv'' INTO TABLE ' + @table
	SET @sql = @sql + ' FIELDS TERMINATED BY '','' ENCLOSED BY ''\"'' LINES TERMINATED BY ''\r\n'';';
	SET @sql = @sql + 'COMMIT;';

/* 2 Execute it */

	SET @cmd = 'G:\Export\MySql\bin\mysql.exe --defaults-extra-file=G:\Export\MySql\'' + @database + '.cnf -e "' + @sql + '";';
	EXEC @IsError = master..xp_cmdshell @cmd;
	IF @IsError <> 0 RAISERROR('INFILE Error', 16, 1);

/* 3 Defragment table and Update stats */

	SET @sql = 'OPTIMIZE TABLE ' + @table + ';';
	SET @cmd = 'G:\Export\MySql\bin\mysql.exe --defaults-extra-file=G:\Export\MySql\' + @database + '.cnf -e "' + @sql + '";';
	EXEC @IsError = master..xp_cmdshell @cmd;
	IF @IsError <> 0 RAISERROR('OPTIMIZE Error', 16, 1);

Lines 3: Will need to be changed for each project. And names both the CSV file and target MySQL table.

Line 4: Is a previously created file used by MySQL to connect to a target instance & database.

Lines 12 to 16: Builds up a string of MySQL commands to empty then refill the table from the CSV file.

Lines 12 & 16: These two lines create a single transaction. This serves two purposes. 1) The ‘old data’ will not be deleted if the ‘new data’ load fails. 2) The switch-over from ‘old data’ to ‘new data’ will be instant.

Send an Email with a PDF attached

There are many posts on how to automatically generate of a PDF receipt and email it by leveraging SSRS. Here is how it went for me.

  1. Create a report that shows the details required.
  2. Create a parameters table.
  3. Subscribe to the report using the parameters table.
  4. Create a stored-procedure to populate and fire the subscription.

On a version of SQL Server Reporting Services (SSRS) that supports data-driven-subscriptions (DDS) I created a report called ‘SingleInvoice’ with one input parameter ‘invoice number’.

Outside of this report, in preparation for the DDS, I created a data source pointing to the local [ReportServer] database.

Within the [ReportServer] database I created a table called [dbo].[InvoiceParams]

CREATE TABLE [dbo].[InvoiceParams](
	[InvoiceNumber] [VARCHAR](100) NULL,
	[ToEmailAddress] [VARCHAR](200) NULL,
	[CCEmailAddress] [VARCHAR](200) NULL,
	[BccEmailAddress] [VARCHAR](200) NULL,
	[ReplyToEmailAddress] [VARCHAR](200) NULL,
	[IncludeReport] [BIT] NULL,
	[RenderFormat] [VARCHAR](20) NULL,
	[Priority] [VARCHAR](15) NULL,
	[Subject] [VARCHAR](150) NULL,
	[Comment] [VARCHAR](150) NULL,
	[IncludeLink] [BIT] NULL,
	[Active] [BIT] NULL,
	[DateInserted] [DATETIME] NOT NULL

ALTER TABLE [dbo].[InvoiceParams] ADD  DEFAULT (NULL) FOR [CCEmailAddress]
ALTER TABLE [dbo].[InvoiceParams] ADD  DEFAULT (NULL) FOR [BccEmailAddress]
ALTER TABLE [dbo].[InvoiceParams] ADD  DEFAULT (NULL) FOR [ReplyToEmailAddress]
ALTER TABLE [dbo].[InvoiceParams] ADD  DEFAULT ((1)) FOR [IncludeReport]
ALTER TABLE [dbo].[InvoiceParams] ADD  DEFAULT ('PDF') FOR [RenderFormat]
ALTER TABLE [dbo].[InvoiceParams] ADD  DEFAULT ('Normal') FOR [Priority]
ALTER TABLE [dbo].[InvoiceParams] ADD  DEFAULT ((0)) FOR [IncludeLink]
ALTER TABLE [dbo].[InvoiceParams] ADD  DEFAULT ((1)) FOR [Active]
ALTER TABLE [dbo].[InvoiceParams] ADD  DEFAULT (GETDATE()) FOR [DateInserted]

To simplify the stored procedure I defined default values for all the columns I would not be dynamically populating.

Next I created a Data-driven subscription on the report with a schedule in the past – so it would never fire. For Destination I chose E-Mail.

Within the subscription I edited the dataset and chose the previously created shared data source [ReportServer].

I added this query before clicking ‘Apply’….

FROM dbo.InvoiceParams
WHERE Active = 1;

Back in the New Subscription form, I completed the Delivery options like this …

Within the user database I created this stored-procedure …

  Author:		Richard Smith
  Create date:	10 Jul 2020
  Description:	To Email PDF receipts - demo version
  Test: Exec [dbo].[EmailReceipts] 'INV123456789',

ALTER PROC [dbo].[EmailReceipts]
    @InvoiceNumber VARCHAR(100),
    @ToEmailAddress VARCHAR(200),
    @Subject VARCHAR(150) = 'test subject',
    @Comment VARCHAR(150) = 'test body',
    @SubscriptionID NVARCHAR(260) = '987654321' 
                       /* Report = "SingleInvoice" */

/* 1 Save the inputs */

    INSERT INTO [ReportServer].[dbo].[InvoiceParams] 
            (InvoiceNumber, ToEmailAddress, [Subject], Comment)
    VALUES (@InvoiceNumber, @ToEmailAddress, @Subject, @Comment);

/* 2 Trigger subscription. Which will send the report (+ inputs) to the email-subsystem-queue */

    EXEC [ReportServer].[dbo].[AddEvent] @EventType = 'TimedSubscription', @EventData = @SubscriptionID;
    WAITFOR DELAY '00:00:10';

/* 3 If no longer in queue, flag as sent */

    IF NOT EXISTS (SELECT 1 FROM [ReportServer].[dbo].[Event] WHERE EventData = @SubscriptionID)
        UPDATE [ReportServer].[dbo].[InvoiceParams] 
        SET Active = 0
        WHERE InvoiceNumber = @InvoiceNumber
        AND ToEmailAddress = @ToEmailAddress;

/* 4 Manage the log */

	DELETE FROM [ReportServer].[dbo].[InvoiceParams] WHERE DateInserted < GETDATE()-30;
	SELECT * FROM [ReportServer].[dbo].[InvoiceParams] ORDER BY DateInserted DESC;


When executed with an email address and invoice number this stored procedure will send an email to the email address with the PDF invoice attached.


To find @SubcriptionID I used this …

SELECT SCH.SubscriptionID
FROM [ReportServer].[dbo].[Catalog] CAT
JOIN [ReportServer].[dbo].[ReportSchedule] SCH
  ON CAT.ItemID = SCH.ReportID
WHERE CAT.Path= '/ReportPath/ReportName';

Removing duplicate rows

No need to over develop this – once you realise that the DELETE command can include the TOP option.

More? Ok. Create a SELECT command that shows the issue. EG:-

FROM dbo._op2
WHERE ID = 'X123456';

Add TOP to return just the unwanted rows. IE: if the above query should return 1 row but erroneously returns 2 rows use TOP(1), if it returns 5 rows use TOP(4) …

(NOTE: It does not matter which particular rows get deleted … they are duplicates remember)

FROM dbo._op2
WHERE ID = 'X123456';

Change SELECT to DELETE and remove the column name …

FROM dbo._op2
WHERE ID = 'X123456';

… and only run it once 😉

Stop notification spam

Although I have previously tackled this problem by rolling my own notifications. This time I realised that the SQL jobs that run every minute or two are of low importance – and I don’t really want emails when they fail. I will notice at some point during the working day.

Here is the code to lists jobs that run frequently and are configured to send notification emails. Along with the commands to remove those notifications.

/* JobNotificationEmailStop.sql */

SELECT S.[name] JobName,
    SS.freq_subday_interval [ScheduleFreq(mins)],
    'EXEC msdb.dbo.sp_update_job @job_name = N''' 
    + S.[name] 
    + ''', @notify_email_operator_name = N'''';' 

  FROM msdb.dbo.sysjobs S
  JOIN msdb.dbo.sysjobschedules SJ
    ON S.job_id = SJ.job_id
  JOIN msdb.dbo.sysschedules SS
    ON SS.schedule_id = SJ.schedule_id

 WHERE SS.freq_subday_interval > 0
   AND S.notify_level_email > 0
 ORDER BY SS.freq_subday_interval;

Except and Intersect

Here is the simplest working example of EXCEPT and INTERSECT I can come up with …

/* Except.sql */

INSERT INTO #t1 VALUES (1), (2);

INSERT INTO #t2 VALUES (2), (3);

SELECT * FROM #t2; /* = 1 */

SELECT * FROM #t2; /* = 2 */

SELECT * FROM #t1; /* = 3 */

SELECT * FROM #T1); /* = 1 & 3 */

I use this frequently whilst refactoring to check the outputs are identical. And sometimes when syncing a MySQL table to MSSQL.

How to check SQL Jobs are actually doing something.

Looking through the Database Mail log today, I accidentally discovered a job that had been busy sending emails for I-don’t-know-how-long using an email profile that no longer worked. The output of the job was ‘success’ as the emails had been successfully queued with the Database Mail sub-system.

After finding the emails would have been empty anyway, I disabled the job. But it made me wonder if there might be other jobs that were busy doing nothing – hour after hour – day after day.

Knowing the dangers of weakening the system, I did not want to fail a job or job-step just to flag a maintenance issue.

The lowest-risk change I could think of making (to the many, legacy, unfamiliar jobs) was to leave pertinent messages in the job history log using the PRINT command. For example:-

      PRINT 'YES: there is new data'
      (Do meaningful stuff)
      PRINT 'NO: there is no new data';

Then in the future I might notice that there is Never any new data!

Move a MySQL database

There are many ways to copy (or move) a MySQL database (aka schema) from one server (aka instance) to another (including the data).

On this occasion I used the Export and Import utilities within “MySQL Workbench” (like doing a backup and restore). The fact that the source and target instances were both hosted on GCP was irrelevant (no brackets required!).

1. Connect to Source and start the Data Export utility …

2.Within the utility, I left the defaults as they were, apart from …

  • TIC the schema I wanted to export (see screenshot)
  • Select “Export to Self-Contained File” as I wanted all the tables
  • and create a meaningful dump-file name

3. Because the Export and Import utilities would be using different logins, I clicked “Advanced Options” within the Export utility, and typed “OFF” over the top of the default “AUTO” setting for set-gtid-purged …

…before clicking the “Return” then “Start Export” back on the main page.

4. To keep it simple, I closed and reopened MySQL Workbench before connecting to the Target instance. Then from the Server menu I chose Data Import …

5. I left all the defaults as they were except …

  • I chose “Import from Self-Contained File”
  • and navigated to the dump-file
  • I clicked “New” and typed the schema name that would receive the import.

6. Finally. On the “Import Progress” page I clicked “Start Import”. Then waited about five minutes before anything seemed to happen

Backup KeePass

Its important to have a backup copy of your password vault. An easy and robust solution is to use the Windows Task Scheduler program to schedule a regular backup.

To start, create a folder to hold the script and the backup. For example C:\Temp\Backup\.

Next, create and test a command that copies your keepass file to the backup location EG: “XCOPY C:\Users\88776655\Downloads\Database.kdbx C:\Temp\Backup\ /Y” and save it in a text document within the backup folder. EG: “C:\Temp\Backup\BackupKeePass”.

Change the properties of the “Backup” folder so you can see the file extensions IE: BackupKeePass.txt” …

Then change the extension from txt to bat and test it works (right-click, open).

  • Start up the Task Scheduler by typing it into the Windows search bar.
  • Right-click on “Task Scheduler Library” and create a new folder “My Tasks”.
  • Right-click on “My Tasks” and choose “Create Task”. Give it a name like “Backup KeePass” and click the radio-button “Run whether a user is logged in or not”
  • On the Triggers tab, schedule it or set it to run every log on.
  • On the Actions tab create a new action to start a program and browse to the bat file.
  • On the Settings tab, select “Stop task if runs longer than 1 Hour”, and click OK.

To test make a change in KeePass and save it. The reboot , login and examine the date the backup was created.

Log Shipping to GCP

Whilst it is possible to configure “log shipping” between different versions of SQL Server, the result can only be used for disaster recovery.

This is because “standby mode” (where the data could be read on GCP) requires the same versions of SQL Server on the primary and secondary servers.

The automatic upgrading of the database objects (from say 2008r2, to say 2017), when brought online could not happen fast enough to support the continuous nature of “standby mode”.

Capturing input parameters

Often when a stored-procedure is executed I want to know the parameters that were input. Which is handy for performance tuning.

There is a mechanism to automatically save input parameters with the cached execution plans, but quite often this does not work well.

On this occasion I embedded the facility right into the procedure as a temporary measure (please, don’t talk to me about triggers brrr).

CREATE PROCEDURE [dbo].[sp_SomeName]
 @Record VARCHAR(50) = NULL    

 /* log parameters for performance tuning 1 of 2 */

  IF OBJECT_ID('[SomeDatabase].[dbo].[tbl_SomeTable]') IS NULL
  	INTO [dbo].[tbl_SomeTable]
  	INSERT INTO [dbo].[tbl_SomeTable]

 /* log parameters for performance tuning 1 of 2 */


Overkill really, but at the end of the procedure I added …


/* log parameters for performance tuning 2 of 2 */
  UPDATE [dbo].[tbl_SomeTable]
  SET ETIME = getdate()
 /* log parameters for performance tuning 2 of 2 */


Note: the real procedure had many more input parameters, and I suspected they are all set to null. Which would explain the poor performance.

Still, best to know what we’re optimizing for 🙂

Uploading data to Google’s cloud platform

This project was to refresh data every night from a production SQL Server table to a cloud-based MySQL Server. (see my previous post on preparation).

On the GCP website

I created a minimal MySQL instance (which I think of as a “Server”) with a single zone and a Standard machine type (being 1vCPU and 3.75 GB of memory).

Storage I set to a 100GB HDD. Then added an Authorised Network comprising an ip-address range covering our production servers along with a friendly name. I disabled auto storage increase, backups, and point-in-time recovery.

I created a database specifically for this project, and a User (with password) restricted to the same ip-address as above.

Finally, because I would be copying data from a MS-SQL table into a MySQL table (which is not 100% compatible), I set flag “sql_mode” to “ANSI”.

On the Production SQL Server

I downloaded the current MySQL 32 bit ODBC driver and configured a new ODBC data source.

Then I created a 2-step SQL Job scheduled to run every night.

Step-1 Collects and saves the data into a purpose made table using a stored-procedure. Replacing the old data.

Step-2 Uploads the table from step-1 into the GCP database using an SSIS package.

To help (with tasks like creating, deleting, viewing and testing tables), I installed the MySQL admin tool “My Workbench” locally. Even so, the SSIS package took a time to perfect. It had to :-

  • Connect to the source and target servers.
  • Replace all the target data every time it ran – for robustness.
  • Refer to reserved column names using double-quotes.
  • Ensure target data-type and sizes exactly matched the source.

Uploading data to Google’s cloud platform – preparation

Gotcha! that title makes no sense.

My preparation would all be in my head for this data move from Microsoft SQL Server 2019 to MySQL 8.0. Accessing the former from SQL Server Management Studio and the later through My Workbench.

The cloud is not a new operating system.

The data would NOT be “uploaded”, just copied from a remote Windows SQL Server to a remote Linux MySQL server. And that sounds like a job for SSIS. (preparation complete 🙂 )

Orphaned users

Servers have Logins, and databases have Users.

A Login and a User account are linked, sharing the same name and the same SID. Naturally, for each Login there can be many User accounts – one in each database.

Now, if you backup a database on one server and restore it onto another server. It may contain Users within that database, that do not have a corresponding Login on the second server.

Execute this command (against each user database) to list any orphaned Users

SELECT 	DP.type_desc,
        DP.[name] UserName
FROM [sys].[database_principals] DP
LEFT JOIN [sys].[server_principals] SP
       ON DP.SID = SP.SID
AND DP.authentication_type_desc = 'INSTANCE';

To fix this you can either remove the orphaned user account or create a matching login. Removing a user account is tricky to script as you need to remove individual attributes first.

Creating a login depends on the type, SQL or Windows. For SQL logins paste the name, SID, and password* into this command and execute it.

USE [master]
WITH PASSWORD = 'SomePassword',  
SID = 0xSomeSid;

(*If you do not know the SQL login password that was used on the old server then create a new one. They are not linked)

To create a Windows login use this command …

USE [master]
CREATE LOGIN [SomeDomain\SomeLogin] 

Expensive Spaghetti

Now that cloud computing has made the cost of things more visable. It is easier to see how much money is being wasted carrying around legacy spaghetti code.

Where once I.T. Managers prioritized the task of cleaning up inefficient code that works as “one day”. Now a cloud-compute-unit can be tied directly to cold-hard-cash. “Technical Debt” suddenly has an individual price sticker.

Subtree Cost = DTU’s = Money

Set every users default schema to DBO where its blank

In this quick script I am assuming the Windows domain is called ‘DOM’ …

-- ChangeDefaultSchemaToDboWhereNull.sql

DECLARE @cmd varchar(1000) 

SET @cmd = 
'USE ? IF DB_ID(''?'') > 4 SELECT ''USE ?; ALTER USER ['' + name + ''] WITH DEFAULT_SCHEMA = [dbo]''
 FROM sys.database_principals
 WHERE default_schema_name IS NULL
 AND [name] LIKE ''DOM\%'''

IF OBJECT_ID('tempdb..#output') IS NOT NULL DROP TABLE #output
(command varchar(1000))

EXEC sp_MSforeachdb @cmd

FROM #output

SQL Snapshot worksheet

— snapshots.sql

–1. create a snapshot

USE master;
    NAME = CreditData,
    FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL15.SQL2019\MSSQL\DATA\'
    NAME = CreditCatalog,
    FILENAME = 'C:\Program Files\Microsoft SQL Server\MSSQL15.SQL2019\MSSQL\DATA\'

–2. restore database from a snapshot

USE master;
DECLARE @kill VARCHAR(8000) = '';
SELECT @kill = @kill + 'kill ' + CONVERT(VARCHAR(5), spid) + ';'
  FROM master..sysprocesses
 WHERE dbid = DB_ID('Credit')
   AND spid > 50;
EXEC (@kill);

–3. delete snapshot

USE master;

— testing

FROM [Credit].[dbo].[member]
WHERE member_no = 22

UPDATE [Credit].[dbo].[member]
SET Firstname = 'DRY'
WHERE Firstname = 'CRRY'

FROM [Credit].[dbo].[member] aa
JOIN [Credit_Snap].[dbo].[member] bb
  ON aa.member_no = bb.member_no 
WHERE aa.Firstname <> bb.Firstname;

Transactional Replication causing High CPU

In Publication Properties the setting “Subscriptions never expire …” has a surprising effect on the job “Distribution clean up: distribution”.

This job removes orphaned and replicated transactions from the Distribution database once the retention period has expired.

However, “Subscriptions never expire …” stops this procedure from removing orphaned transactions – left by a deleted subscription – or for any other reason.

This results in the Distribution database growing and high CPU.

To fix this, allow subscriptions to be able to expire.

So failed subscriptions may be deleted if not fixed within a year. This preserves the robustness of “Subscriptions never expire”, whilst allowing orphaned transactions to be cleaned up.

Change SQL Server Collation

To change the default collation of my SQL 2019 instance on my laptop to “SQL_Latin1_General_CP1_CI_AS” I …

– Found the saved the location of sqlservr.exe into notepad.

– Added [cd ] in front of the path (that’s cd and a space, without the square brackets)

– Added a second line in notepad [sqlservr -m -T4022 -T3659 -s”SQL2019″
-q”SQL_Latin1_General_CP1_CI_AS”] (without the square brackets)

– Stopped the SQL Server service

– Opened a Command Prompt as Administrator

– Executed the first command (cd …)

– Executed the second line (sqlservr …)

– Rebooted.

Save emergency contact details to Azure Blob Storage

This was part of the business continuity plan, so that HR had a list of employees next-of-kin etc, off-site.

I created a Job with 2 steps (Export using BCP and Import using AZCopy).

-- bcp.sql

-- Create the command to be executed

	DECLARE @cmd VARCHAR(1000) = 
                'bcp SomeDatabase..SomeView out 
                E:\SomePath\SomeFileName.txt -c -t, -T -S' + @@servername;

-- Run this if command-prompt is disabled

	IF (SELECT value_in_use FROM sys.configurations WHERE name = 'xp_cmdshell') = 0
		EXEC sp_configure 'show advanced options', 1; RECONFIGURE; -- show advanced options
		EXEC sp_configure xp_cmdshell, 1; RECONFIGURE; -- enable command-shell
		EXEC xp_cmdshell @cmd; -- run the command
		EXEC sp_configure 'xp_cmdshell', 0; RECONFIGURE; -- disable command-shell
		EXEC sp_configure 'show advanced options', 0; RECONFIGURE; -- hide advanced options

-- Run this if command-prompt is enabled
		EXEC xp_cmdshell @cmd;

Step-1 overwrites the file each time.

In preparation for the azcopy command I used Azure Explorer to connect and create a fileshare called “BCExtract”.

Right-Clicking on this I chose “Generate Shared Access Signature”, and “Ad hoc Shared Access Signature”. I left all the defaults as they were except I increased Expiry time a bit.

I pasted the “Shared Access Signature URI” into notepad, added a backslash, then the “Shared Access Signature Token” making one long string.

Before this string I added “azcopy copy ” then the local path to the CSV file in double quotes.

-- azcopy.sql

-- Create the command to be executed

	DECLARE @cmd VARCHAR(1000) = 
		'azcopy copy "E:\SomePath\SomeFileName.txt" 

-- Run this if command-prompt is disabled

	IF (SELECT value_in_use FROM sys.configurations WHERE name = 'xp_cmdshell') = 0
		EXEC sp_configure 'show advanced options', 1; RECONFIGURE; -- show advanced options
		EXEC sp_configure xp_cmdshell, 1; RECONFIGURE; -- enable command-shell
		EXEC xp_cmdshell @cmd; -- run the command
		EXEC sp_configure 'xp_cmdshell', 0; RECONFIGURE; -- disable command-shell
		EXEC sp_configure 'show advanced options', 0; RECONFIGURE; -- hide advanced options
-- Run this if command-prompt is enabled
		EXEC xp_cmdshell @cmd;

Dropping a user that owns a schema (Error: 15138)

Manually highlight and run #1. Paste the result into #2.

-- DropFailedForUser.sql

-- The statement (that caused the error)

   USE [master] -- in this case
   DROP USER [Dom\SomeUser]

/* The Error ...

   Drop failed for user 'Dom\SomeUser'
   The database principal owns a schema in the database
   and cannot be dropped. Error: 15138

-- #1. find the name of the schema

   SELECT [name]
   FROM sys.schemas s
   WHERE s.principal_id = USER_ID('Dom\SomeUser');

-- #2. transfer ownership of the schema to 'dbo'


-- repeat "The Statement"

Redgate SQL Data Compare

I love this tool for refactoring. With a result set of over 3,000 rows across 60 columns, eyeballing similar outputs in a spreadsheet just would not do.

To use this tool, I modified the original query to output INTO a new table “_output” in the current database. Near the start of the query I put an IF EXISTS/DROP statement (more commonly used with temp tables), and at the bottom of the query I selected star from _output.

After improving the original query code (and saving it with a new name), I modified it similarly to the above – outputting results INTO table “_output” but in a DIFFERENT database.

I configured “SQL Data Compare” to use every column of the first “_output” table as a “comparison key”. And can now confirm the two tables called “_output” in different databases are identical.

Drop all tables that start with underscore

In an ironic twist of fate I adapted my ‘Drop all temp-tables’ script, to drop all tables beginning with an underscore.

Yes, it is ironic, because it uses a temp-table to store the working list of tables to be deleted. Whilst my original script used a real table to store a list of temp-tables.

Well … ok then

-- DropAllTablesStartingWithAnUnderscore.sql

IF OBJECT_ID('tempdb..#tables') IS NOT NULL DROP TABLE #tables
SELECT [name] 
INTO #tables
FROM sys.tables
WHERE [name] LIKE '/_%' ESCAPE '/'

DECLARE @table VARCHAR(200), @cmd VARCHAR(500)
WHILE (SELECT COUNT(*) FROM #tables) > 0
	SET @table = (SELECT TOP(1) [name] FROM #tables)
	SET @cmd = 'drop table ' + @table
	DELETE FROM #tables WHERE [name] = @table

(In case you were wondering why I created these underscore-tables in the first place. I was refactoring a stored-procedure that took over an hour to run, and had a large number of temp-tables. I wanted to persist those temp-tables for another day, and not have to start from scratch.)

Find the partner of a bracket in SSMS

Faced with a barrage of tabbed T-SQL in SSMS it can sometimes be quite difficult to see the close bracket that signifies – for example – the end of a CTE.

TIP: swipe from the inside of the bracket outwards to highlight (in grey) the bracket itself, and also its partner. EG: swipe right-to-left across an open bracket.

Running CHECKDB on TempDB

Normally I would not bother, but when CHECKDB runs on TempDB it cannot use a snapshot so has to lock all the temp tables. This script will wait for exclusive access for up to a minute.

DECLARE @outcome VARCHAR(50) = 'TempDB is currently too busy for CHECHDB', 
	@endtime DATETIME = DATEADD(mi,1,GETDATE())
WHILE GETDATE() < @endtime
  IF NOT EXISTS (SELECT 1 FROM sys.dm_tran_locks WHERE request_mode = 'X' AND resource_database_id = 2)
    DBCC CheckDB([tempdb]) WITH NO_INFOMSGS;
    SET @outcome = 'success'
  WAITFOR DELAY '00:00:01';
SELECT @outcome

A TDE test restore

Post migration, I wanted to make sure an encrypted database on a new SQL 2014 Enterprise edition server could be restored.

I installed SQL 2014 Developer edition on a second machine and initially got the expected error …

Msg 33111, Level 16, State 3, Line 2
Cannot find server certificate with thumbprint.
Msg 3013, Level 16, State 3, Line 2
RESTORE DATABASE is terminating abnormally

1. I checked if the target server was enabled for TDE …

SELECT * FROM sys.symmetric_keys

This returned one row, I checked against the source server and that returned two rows. I concluded that the target server was NOT yet TDE enabled.

2. To enable TDE on the target …

USE Master
BY PASSWORD = '[SomePwIJustMadeUp]';

3. Next I copied over the two files (*.cer and *.pvk) from the backup location to the target server and installed the certificate into Master …

USE Master
CREATE CERTIFICATE [NameOfTheDatabase]_Cert2
FROM FILE = '[PathAndNameOfLocalCopyOfCertFile].cer'
WITH PRIVATE KEY (FILE = N'[PathAndNameOfLocalCopyOfPvkFile].pvk',
	  DECRYPTION BY PASSWORD ='[TheSourcePwIGotFromKeepAss]');

4. After which I was able to restore the database as normal.

Docker installs

The traditional way to the install something like 7zip on a Windows laptop would be:-

  • Use Google to find the software’s website.
  • Go there and download a zip or MSI file
  • Run the (unzipped) installer or MSI file
  • Start the software by clicking a desktop icon or finding it in “all programs”.

The equivalent steps in docker would be:-

  • Find the software on docker hub with docker search
  • Downloads the software image with docker pull
  • Create a container from the image with docker create
  • Start the software by running the container with docker start

However, a better way would be:-

  • Find the software on docker hub with docker search
  • Download, unpack, install, and start the software with docker run

Searching every Procedures for a string.

To search every stored procedure in every database on every server (ranging from SQL Server 2005 to SQL Server 2016) for the string ‘QueryTraceOn’, I first registered every server within SSMS.

Right-clicking on the registered server folder, I chose ‘new query’ and ran ‘select 1’ to exclude from my list any server with issues.

Once I had an error free list, I ran this code (which took around 40 minutes) …

-- SearchProcs4String.sql

EXEC sp_MSforeachdb 'use ?
SELECT db_name() [Database], ROUTINE_SCHEMA + ''.'' 

Getting away from Dedupe jobs

Duplicate data should ideally be stopped at the front end. However if a table already contains duplicate data you may want to bash out some code to clean it up. And schedule a SQL job to run the code regularly.

However, there are mechanisms baked right into SQL Server to manage this more efficiently (step away from scripting everything – devops 😉 )

True enough, you need to run code (once) to clean out all the current duplicates, but going forward a unique filtered index can keep them out.

For this particular project “duplicate data” meant that an CustID column should not contain a number already in that column if the Country was ‘GB’ and the PackageID was ‘5’.

Here is a simplified example of my solution …

-- ix_BlockDupCustIDs.sql

CREATE TABLE #t1 (CustID INT, CountryCode CHAR(2), PackageID INT);

ON #t1 (CustID) 
WHERE CountryCode = 'GB' AND PackageID = 5;

INSERT INTO #t1 VALUES (1, 'GB', 5) -- yes
INSERT INTO #t1 VALUES (2, 'GB', 5) -- yes
INSERT INTO #t1 VALUES (1, 'GB', 4) -- yes
INSERT INTO #t1 VALUES (1, 'US', 5) -- yes
--INSERT INTO #t1 VALUES (1, 'GB', 5) -- no, duplicate
--INSERT INTO #t1 VALUES (2, 'GB', 5), (3, 'IR', 1) -- no for both
--UPDATE #t1 SET PackageID = 5 WHERE PackageID = 4 -- nope


How to run SQL Server within Docker

Here is my bare-bones walk-through for setting up SQL Server Developer Edition within Docker for those of us who don’t have time to learn docker right now.

1. I navigated to the Docker website and read about Docker Desktop before installing Docker Desktop for Windows (and creating an account) from my Windows 10 Pro laptop.

During installation I chose to use Windows containers by default, rather than Linux.

2. To find SQL Server Developer Edition, I reached out to the Docker Hub online library from my laptop with this command (typed into a Command-Prompt or Powershell window)

docker search mssql

… which brought back this list …

Annotation 2020-04-04 113431

The second item down on the list is from Microsoft, is in a Windows container, and is the Developer edition.

I copied the name into Notepad and composed this command around it to download, extract, and run SQL Server within a docker container …

docker run -d -p 1433:1433 -e sa_password=Pa55word# -e ACCEPT_EULA=Y --restart always -v C:\temp:c:\temp -v sqldata:c:\var\opt\mssql microsoft/mssql-server-windows-developer

Breaking down that command …

  • Docker = invoke Docker
  • Run = download, extract, and execute something from Docker Hub.
  • -d = detached mode. That is, run independent of the command line.
  • -p 1433:1433 = map external port 1433 to internal port 1433.
  • -e sa_password=Pa55word# = create an environment variable called sa_password containing the text “Pa55word#” (without the double quotes).
  • -e ACCEPT_EULA=Y = create another variable called ACCEPT_EULA containing the value “Y”.
  • –restart always = automatically start when Windows starts
  • -v c:\temp:c:\temp = map my laptop folder c:\temp to the docker folder c:\temp
  • -v sqldata:c:\var\opt\mssql = persist user databases
  • microsoft/mssql-server-windows-developer = this is the thing to “Run” (see above).

When complete (after 30 minutes or so) I connected via my regular laptop SSMS (IE: outside of the container) …

Annotation 2020-04-04 110654

… and added it to my registered servers as “Docker SQL Server Developer edition”

(Incidentally, that server name “dot” implies the local default instance on the default port. I could just as correctly have typed “localhost” or “localhost,1433”. Or from another laptop I would have used the IP address of the host laptop.)

Next I changed my Windows setting so the Docker icon would always be visible …


… so that on subsequent boots, I just need to wait for the icon to stop wobbling before connecting to the database via SSMS (and no need for any pesky Docker commands).

To import a backup I moved it to my laptop c:\temp and restored from there using SSMS.

“And finally” (as the late, great, Ronnie Corbett used to say), if after a while it all goes horribly wrong, as software tends to do, you can either uninstall docker and start this article again.

Or venture into the docker command-line to list (docker ps), stop (docker stop ~), then remove the SQL container (docker rm ~). Before using the green command above again.

More on pesky Docker commands soon.

Migrating to SQL Server 2017 / 2019

(for JH) When migrating to SQL Server 2017 or SQL Server 2019 the name of the game is “Risk Mitigation”. Avoid the temptation to bundle other improvements into the project. Business continuity is first, last, and everything in between.

Server Architecture should be duplicated Exactly in the new environment.

Server Rationalization – nope. Before the migration would be best, because if unexpected issues arise you are on familiar ground. But you have unused logins? databases? jobs? – double nope (Before or after, not during).

SQL Server Role based security – nope. That has been best practice for the last 20 years. This is not the time to make up for lack of database administration. 21 years will be fine.

High Availability – Avoiding downtime is important and HA helps with that. But as long as you have a mature backup system in place, this can wait until the migration is complete. Nope.

Backups – Are less clear cut. But even if the old system is a quirky high maintenance mill stone. It is still familiar, and you don’t want to add unfamiliar complexity at this time. This should be next on your list though.

Disaster Recovery – There are new toys, like clusterless AG’s but again – nope.

Compatibility Level – Should match the old system. A few months after the deed is done, you can quietly try switching less important databases, one at a time (database administration is a perpetual business).

SSIS Packages – Should be rationalized from Packages to Projects … after the migration. Oh and if a package fails after being moved and upgraded, change the environment NOT the package.

Encryption is much easier with modern versions of SQL Server. Schedule this for a few months down the line.

Cardinality Estimator – You may have picked up on a theme here 🙂 – nope. Set it to legacy for reliable performance, for now.