Can I alter my memory optimized table? Like adding column or changing data types etc. If yes, how to do it?
I am using SQL Server 2014
Thanks
According to Altering Memory-Optimized Tables (SQL Server 2014):
Performing ALTER operations on memory-optimized tables is not
supported. This includes such operations as changing the bucket_count,
adding or removing an index, and adding or removing a column. This
topic provides guidelines on how to update memory-optimized tables.
Updating the definition of a memory-optimized table requires you to create a new table with the updated table definition, copy the data to the new table, and start using the new table.
But it will be possible with SQL Server 2016:
In SQL Server 2016 Community Technology Preview 2 (CTP2) you can
perform ALTER operations on memory-optimized tables by using the ALTER
TABLE statement. The database application can continue to run, and any
operation that is accessing the table is blocked until the alteration
process is completed.
In the previous release of SQL Server, you had to manually complete
several steps to update memory-optimized tables.
Related
I have two tables: table 1 is disk based storage and table 2 is in memory storage. I create a DML trigger on table 2 and in that trigger, I insert a record into table 1. Will it be possible?
You can't, it's not possible in the same in-memory transaction using mvcc isolation access a disk-based table through the trigger.
For workaround this you could saving to a stage table memory-based inside the trigger and insert or update to table 1 from stage table using update-join between a memory-based-disk and table-based-disk although it cames with some admin to manage and control but works.
DDL Tiggers still doesn't work even SQL 2017.
Using SSIS - VS 2008
Microsoft SQL Server 2008 R2 (SP2) - 10.50.4000.0 (X64)
I am trying to do a bulk update using a staging table. The staging table is an exact schema copy of my destination table. I have read that Indexes can hamper the performance of uploads to a staging table using the fastload option. So I disable the index before the data flow task and rebuild the index after.
However my SSIS package fails on runtime validation. It seems I cannot do a fastload to the staging table with the indexes disabled. This is the error message I recive: The query processor is unable to produce a plan because the index 'PK_StagingTable' on table or view 'StagingTable' is disabled."
If I remove the command where the index is disabled (Step 3 becomes just truncate table StagingTable) then the SSIS package works.
The question is should this have worked with the index disabled or is that just bad advice? Is there something missing from the instructions that would allow the insert to work with indexes disabled?
The destination table (in this case a staging table) you want to use SSIS' fastload option on can have the indexes disabled beforehand, but it will only work if the indexes are non-clustered. In my specific situation, the table I made a schema copy of had a Primary Key, which means it had a clustered-index. I removed the Primary Key on the staging table and created a non-clustered index using the same columns.
I am trying to find a highly efficient method of auditing changes to data in a table. Currently I am using a trigger that looks at the INSERTED and DELETED tables to see what rows have changed and inserts these changes into an Audit table.
The problem is this is proving to be very inefficient (obviously!). It's possible that with 3 thousand rows inserted into the database at one time (which wouldn't be unusual) that 215000 rows would have to be inserted in total to audit these rows.
What is a reasonable way to audit all this data without it taking a long time to insert in to the database? It needs to be fast!
Thanks.
A correctly written trigger should be fast enough.
You could also look at Change Data Capture
Auditing in SQL Server 2008
I quite often use AutoAudit:
AutoAudit is a SQL Server (2005, 2008, 2012) Code-Gen utility that creates
Audit Trail Triggers with:
Created, CreatedBy, Modified, ModifiedBy, and RowVersion (incrementing
INT) columns to table
Insert event logged to Audit table
Updates old and new values logged to Audit table Delete logs all
final values to the Audit table
view to reconstruct deleted rows
UDF to reconstruct Row History
Schema Audit Trigger to track schema changes
Re-code-gens triggers when Alter Table changes the table
Update: (Original edit was rejected, but I'm re-adding it):
A major upgrade to version 3.20 was released in November 2013 with these added features:
Handles tables with up to 5 PK columns
Performance improvements up to 90% faster than version 2.00
Improved historical data retrieval UDF
Handles column/table names that need quotename [ ]
Archival process to keep the live Audit tables smaller/faster but retain the older data in archive AutoAudit tables
As others already mentioned - you can use Change Data Capture, Change Tracking, and Audit features in SQL Server, but to keep it simple and use one solution to track all SQL Server activities including these DML operations I suggest trying ApexSQL Comply. You can disable all other, and leave DML auditing option only
It uses a centralized repository for captured information on multiple SQL Server instances and their databases.
It would be best to read this article first, and then decide on using this tool:
http://solutioncenter.apexsql.com/methods-for-auditing-sql-server-data-changes-part-9-the-apexsql-solution/
SQL Server Notifications on insert update delete table change
SqlTableDependency C# componenet provides the low-level implementation to receive database notification creating SQL Server Queue and Service Broker.
Have a look at http://www.sqltabledependency.it/
For any record change, SqlTableDependency's event handler will get a notification containing modified table record values as well as DML - insert, update, delete - change executed on your database table.
You could allow the table to be self auditing by adding additional columns, for example:
For an INSERT - this is a new record and it's existence in the table is the audit itself.
With a DELETE - you can add columns like IsDeleted BIT \ DeletingUserID INT \ DeletingTimestamp DATETIME to your table.
With an UPDATE you add columns like IsLatestVersion BIT \ ParentRecordID INT to track version changes.
I'm attempting to use Database Engine Tuning Advisor to tune my database. From the comments it's logging (it's just 40% into the analysis, after running all weekend) it appears that DTA is not capable of tuning operations on Temporary tables. Is that in fact the case?
No. Because in order to apply an index to a transient temporary table you would have to add the index to the script that used the temporary table. It can't just be applied to a non-permanent table as a set-and-forget operation.
What you can do is create a real table with the same name in your database and remove the creation of the temp table from scripts and replace with TRUNCATE TABLE. If you create this table, and then perform actions against it, the DTA will recommend indexing for the permanent table. You then script these recommended indexes, and add them to the temp table in your script.
Also: be aware that while the DTA does a pretty good job in most cases, it doesn't always get it right...
I am trying to understand the tempDB and following are the doubts popping in my mind.
What is the lifetime of data in tempDB? Say a query is doing some Order By and uses tempDB for performing that. After this query finishes, someone else also executes a query which utilizes the tempDB. Will the second query find records written by first query in the tempDB or will they be deleted?
Are there any visible tables created inside the tempDB by the Sql Engine? How can I know which temporary table is created because of this query? Is there any naming convention followed by the Sql engine for naming these temporary tables?
I am new to tempDB so please pardon me for asking such silly (if at all) questions :-)
It will be very nice if someone can point me to a good resource which can help me learn about tempDB.
Temp table is stored in tempdb until the connection is dropped (or in the case of a global temp tables when the last connection using it is dropped). You can also (and it is a good practice to do so) manually drop the table when you are finished using it with a drop table statement.
No, others cannot see your temp tables if they are local temp tables (They can see and use global temp tables) Multiple people can run commands which use the same temp table name but they will not be overlapping in a local temp table and so you can have a table named #test and so can 10,000 other users, but each one has its own structure and data.
You don't want to generally look up temp tables in tempdb. It is possible to check for existence, but that is the only time I have ever referenced tempdb directly. Simply use your temp table name. Example below of checking for existence
IF OBJECT_ID('TempDB.dbo.#DuplicateAssignments') IS NOT NULL
BEGIN
DROP TABLE #DuplicateAssignments
END
You name temp tables by prefacing the name with # (for local tables the ones you would use 999.9% of the time) and ## for global temp tables, then the rest of the name you want.
There's a few MSDN articles that are probably the best source of information on the tempDB database in SQL Server.
tempdb Database
The tempdb system database is a global
resource that is available to all
users connected to the instance of SQL
Server and is used to hold the
following:
Temporary user objects that are explicitly created, such as: global or
local temporary tables, temporary
stored procedures, table variables, or
cursors.
Internal objects that are created by the SQL Server Database Engine, for
example, work tables to store
intermediate results for spools or
sorting.
Row versions that are generated by data modification transactions in a
database that uses read-committed
using row versioning isolation or
snapshot isolation transactions.
Row versions that are generated by data modification transactions for
features, such as: online index
operations, Multiple Active Result
Sets (MARS), and AFTER triggers.
Operations within tempdb are minimally
logged. This enables transactions to
be rolled back. tempdb is re-created
every time SQL Server is started so
that the system always starts with a
clean copy of the database. Temporary
tables and stored procedures are
dropped automatically on disconnect,
and no connections are active when the
system is shut down. Therefore, there
is never anything in tempdb to be
saved from one session of SQL Server
to another. Backup and restore
operations are not allowed on tempdb.
There's also tempdb and Index Creation, this blog post along with Working with tempdb in SQL Server 2005 which states:
The SQL Server system database, tempdb, has undergone a number of changes in SQL Server 2005. There are new tempdb usages and internal optimizations in SQL Server 2005; tempdb architecture is mostly unchanged since SQL Server 2000.
The tempdb system database is very similar to a user database. The main difference is that data in tempdb does not persist after SQL Server shuts down.
The temporary tables created in TempDB are dropped when the query is completed.
I'm not sure on this (I would have to try it), but I think theoretically ALL tables created in TempDB are visible, although only the user that created the table has permission to access it.