For the purpose of my project I cannot use session based temp tables. They need to be persistent but automatically deleted after a certain period of inactivity (no CRUD performed). Is this at all possible?
You can use the SQL Server Agent to Schedule a Job that calls a Stored Procedure that does this work for you. (How to Schedule a Job?)
How do you identify the tables that have not updated since X amount of time ?
Use this Query:
SELECT OBJECT_NAME(OBJECT_ID) AS TableName, last_user_update,
FROM sys.dm_db_index_usage_stats
WHERE database_id = DB_ID('DatabaseName')
AND OBJECT_NAME(OBJECT_ID) LIKE '%%' -- Here is the template name for your tables
AND DATEDIFF(MINUTE, last_user_update, GETDATE()) > 10 -- Last updated more than 10 minutes
Now that you have the tables to be deleted, you can use whatever logic you want to DROP them (Cursor, While, Procedure)
Sure it is. Write it into your program layer.
AUTOMATICALLY - within SQL Server: no. Well, you cold use the agent to start a script regularly.
Tracking what "inactivity" means - your responsibility.
You need save modification date of this table somewhere (for example in the same table or in another special table) and then you can create job, which checks last modification date and then drops the table.
Related
We have external table created, we need to run select on the table and select all the records, the select runs very very slow. Its not completing even after 30 mins, the table contains around 2millon recs
We also need to query this table from another DB and even this runs very very slow, doesn't return even after 30 mins.
Select is of the form:
select col1, col2,...col3 from ext_table;
Need help in:
1. Any suggestions on reducing the time taken for execution?
Note: we need to select entire content of the table so where condition might not be used.
Thanks in advance.
If you are not using the WHERE clause to push parameters to the remote database, then there is no way to optimize the performance of the query. You are returning the whole table.
My suggestion is to use SQL Data Sync to have a local copy of the table on this SQL Database that synchronizes with the remote Azure SQL Database at X interval of time.
I am just wondering, can I find out if somebody wrote a query and updated a row against specific table in some date?
I tried this :
SELECT id, name
FROM sys.sysobjects
WHERE NAME = ''
SELECT TOP 1 *
FROM ::fn_dblog(NULL,NULL)
WHERE [Lock Information] LIKE '%TheOutoput%'
It does not show me ?
Any suggestions.
No, row level history/change stamps is not built into SQL Server. You need to add that in the table design. If you want an automatic update date column it would typically be set by a trigger on the table.
There is however a way if you really need to find out what happened in a forensics scenario. But that is only available if you have the right backup plans. What you can do then is to use the DB transaction log to find when the modification was done. Note that this is not anything an application can or should do runtime.
I need to create a "ghost" table in SQL Server, which doesn't actually exist but is a result set of a SQL Query. Pseudo code is below:
SELECT genTbl_col1, genTblcol2
FROM genTbl;
However, "genTbl" is actually:
SELECT table1.col AS genTbl_col1,
table2.col AS genTbl_col2
FROM table1 INNER JOIN table2 ON (...)
In other words, I need that every time a query is run on the server trying to select from "genTbl", it simply creates a result set from the query and treats it like a real table.
The situation is that I have a software that runs queries on a database. I need to modify it, but I cannot change the software itself, so I need to trick it into thinking it can actually query "genTbl", when it actually doesn't exist but is simply a query of other tables.
To clarify, the query would have to be a sort of procedure, available by default in the database (i.e. every time there is a query for "genTbl").
Use #TMP
SELECT genTbl_col1, genTblcol2
INTO #TMP FROM genTbl;
It exists only in current session. You can also use ##TMP for all sessions.
I am setting up a Cron Job that will run every 15 minutes and if there is new data in a particular table it will back up that table, email it and delete it.
Do I have to be concerned that data will be written to the database at the same time as the backup is running and it will backup "half" the data and than delete the rest of it?
If your job operates as you have described, there is a risk that new data could be added to the table after the SELECT used to generate the email but before the DELETE.
The simplest way to prevent this might be to run the two statements inside a transaction, assuming the database engine you're using supports transactions.
Alternatively, some database engines support returning data from a DELETE statement in a single atomic transaction - Postgres being one, with the RETURNING clause.
If that option isn't available to you, another solution would be to drive the DELETE using a high-water date/time or auto-incrementing identity column in the source table.
Implementing this might require a schema change to your source table.
Pseudo-code would be something like:
SELECT <variable> = max(<identity>)
FROM source_table
SELECT <columns>
FROM source_table
WHERE <identity> <= <variable>
DELETE source_table
WHERE <identity> <= <variable>
Any data added to source_table between the first SELECT and the DELETE will have a higher identity value than is stored in <variable>, so will not be removed.
I want to insert some data on the local server into a remote server, and used the following sql:
select * into linkservername.mydbname.dbo.test from localdbname.dbo.test
But it throws the following error
The object name 'linkservername.mydbname.dbo.test' contains more than the maximum number of prefixes. The maximum is 2.
How can I do that?
I don't think the new table created with the INTO clause supports 4 part names.
You would need to create the table first, then use INSERT..SELECT to populate it.
(See note in Arguments section on MSDN: reference)
The SELECT...INTO [new_table_name] statement supports a maximum of 2 prefixes: [database].[schema].[table]
NOTE: it is more performant to pull the data across the link using SELECT INTO vs. pushing it across using INSERT INTO:
SELECT INTO is minimally logged.
SELECT INTO does not implicitly start a distributed transaction, typically.
I say typically, in point #2, because in most scenarios a distributed transaction is not created implicitly when using SELECT INTO. If a profiler trace tells you SQL Server is still implicitly creating a distributed transaction, you can SELECT INTO a temp table first, to prevent the implicit distributed transaction, then move the data into your target table from the temp table.
Push vs. Pull Example
In this example we are copying data from [server_a] to [server_b] across a link. This example assumes query execution is possible from both servers:
Push
Instead of connecting to [server_a] and pushing the data to [server_b]:
INSERT INTO [server_b].[database].[schema].[table]
SELECT * FROM [database].[schema].[table]
Pull
Connect to [server_b] and pull the data from [server_a]:
SELECT * INTO [database].[schema].[table]
FROM [server_a].[database].[schema].[table]
I've been struggling with this for the last hour.
I now realise that using the syntax
SELECT orderid, orderdate, empid, custid
INTO [linkedserver].[database].[dbo].[table]
FROM Sales.Orders;
does not work with linked servers. You have to go onto your linked server and manually create the table first, then use the following syntax:
INSERT INTO [linkedserver].[database].[dbo].[table]
SELECT orderid, orderdate, empid, custid
FROM Sales.Orders
WHERE shipcountry = 'UK';
I've experienced the same issue and I've performed the following workaround:
If you are able to log on to remote server where you want to insert data with MSSQL or sqlcmd and rebuild your query vice-versa:
so from:
SELECT * INTO linkservername.mydbname.dbo.test
FROM localdbname.dbo.test
to the following:
SELECT * INTO localdbname.dbo.test
FROM linkservername.mydbname.dbo.test
In my situation it works well.
#2Toad: For sure INSERT INTO is better / more efficient. However for small queries and quick operation SELECT * INTO is more flexible because it creates the table on-the-fly and insert your data immediately, whereas INSERT INTO requires creating a table (auto-ident options and so on) before you carry out your insert operation.
I may be late to the party, but this was the first post I saw when I searched for the 4 part table name insert issue to a linked server. After reading this and a few more posts, I was able to accomplish this by using EXEC with the "AT" argument (for SQL2008+) so that the query is run from the linked server. For example, I had to insert 4M records to a pseudo-temp table on another server, and doing an INSERT-SELECT FROM statement took 10+ minutes. But changing it to the following SELECT-INTO statement, which allows the 4 part table name in the FROM clause, does it in mere seconds (less than 10 seconds in my case).
EXEC ('USE MyDatabase;
BEGIN TRY DROP TABLE TempID3 END TRY BEGIN CATCH END CATCH;
SELECT Field1, Field2, Field3
INTO TempID3
FROM SourceServer.SourceDatabase.dbo.SourceTable;') AT [DestinationServer]
GO
The query is run on DestinationServer, changes to right database, ensures the table does not already exist, and selects from the SourceServer. Minimally logged, and no fuss. This information may already out there somewhere, but I hope it helps anyone searching for similar issues.