System.OutOfMemoryException when querying large SQL table - sql

I've written a SQL query that looks like this:
SELECT * FROM MY_TABLE WHERE ID=123456789;
When I run it in the Query Analyzer in SQL Server Management Studio, the query never returns; instead, after about ten minutes, I get the following error: System.OutOfMemoryException
My server is Microsoft SQL Server (not sure what version).
SELECT * FROM MY_TABLE; -- return 44258086
SELECT * FROM MY_TABLE WHERE ID=123456789; -- return 5
The table has over forty million rows! However, I need to fetch five specific rows!
How can I work around this frustrating error?
Edit: The server suddenly started working fine for no discernable reason, but I'll leave this question open for anyone who wants to suggest troubleshooting steps for anyone else with this problem.

According to http://support.microsoft.com/kb/2874903:
This issue occurs because SSMS has insufficient memory to allocate for
large results.
Note SSMS is a 32-bit process. Therefore, it is limited to 2 GB of
memory.
The article suggests trying one of the following:
Output the results as text
Output the results to a file
Use sqlcmd
You may also want to check the server to see if it's in need of a service restart--perhaps it has gobbled up all the available memory?
Another suggestion would be to select a smaller subset of columns (if the table has many columns or includes large blob columns).

If you need specific data use an appropriate WHERE clause. Add more details if you are stuck with this.
Alternatively write a small application which operates using a cursor and does not try to load it completely into memory.

Related

How does SSMS show partial results of a large resultset whilst the query is still running, and can equivalent behaviour be achieved in .NET?

In SQL Server Management Studio, when running a query that produces a very large resultset, it appears to sometimes display the results of the resultset as it's loading them, rather than them all appearing at once.
My normal assumption would be that it's simply it populating the grid(s) in SSMS with the results of the finished query, and that the SQL query itself is finished.
However, if I run the following query:
SELECT 1
SELECT * FROM EnormousTable
INSERT INTO SomeOtherTable([Column1]) SELECT 'Test3'
That last INSERT does not occur until after the results from the larger resultset have been fully returned.
I have two main questions:
1. What is happening here? Is SSMS breaking down the query into separate batches even without GO statements? Please note that I'm not a DBA, so if there's some fundamental reason for this behaviour that 'any DBA would know', there's a good chance I don't know it.
2. Is there a way to attain similar functionality in .NET? What I mean by this is, when running a set of queries that will produce multiple resultsets, whether or not it's possible to have a DataSet get populated with the results of each successive query as it finishes (without waiting for all the queries to finish), without me having to manually break down the query (unless that's what SSMS is actually doing under the hood).

SQL Query - Finding Current log file usage for one database

I want to set up some monitoring software that will generate an SMNP trap if a database log file goes beyond about 95% usage. It can only look at the first result in the first column of an SQL query, so what I'm looking for is an SQL Query which will just return the percentage figure ONLY in the result - eg, 95
I've found several different ways of doing similar things, but all return table heading etc, whereas I just want the figure. It'll be running this query every hour so nothing too intensive. I'm running SQL version 8.
Thanks, Mike
You could write a query against the OS DMVs to get just the single value you're looking for.
Not sure if this will work for SQL Server 2000, but I know it works as far back as SQL Server 2005. It also requires that performance counters are enabled on the host server (i.e. OS, not just SQL Server).
This query should do the trick:
SELECT cntr_value as PercentUsed
FROM sys.dm_os_performance_counters
WHERE counter_name = 'Percent Log Used'
AND instance_name = 'your_database_name'

Excel query showing different result than SSMS query

I have had an odd error I cannot explain. Basically, I am running a query to my SQL database using excel and am having non-existent data pop up when it comes to a very particular order in my database.
Here is a simple query surrounding this order:
select * from OR200100 where OR200100.OR20001='0000793605'
Here is the output in EXCEL
And here is the same output in SQL
what is happening here? How could the same query generate 2 different results?
Run SQL Server Profiler against the database if you can, then compare the output to the sql query that you are running in ssms.
OK, so it's SQL Server then, that's important because different SQL products can have very different idiosyncrasies and controls.
The next things to check are these:
Is OR200100 a Table or a View? If it's a view then post it's code.
Are you using the same Login/account from both Excel and SSMS?
Are you sure that you are connecting to the same Server and Database? SSMS tells you what you are connected to, but client apps like Excel do not and it is very common for this type of problem to be caused by the app connecting to a Dev or QA version of the database. See here for some of the different ways that this can happen:
So I had a very similar problem, my query was grouping by week numbers. What I found was that one of the queries had set datefirst 5 set whilst the other didn't. I guess the key thing here is make sure, if you are using any SET operations in your ssms queries, these are identical to those in the Excel query string.

Results returned from a view using linked server may vary?

i have a view that is using linked server to retrieve data from a remote server in SQL Server. On each time viewing the view, the results returned are vary. For example, 1st time execution may return 100 rows of records but on 2nd time of execution, rows returned are 120 rows. Any ideas what is the cause?
I have witnessed odd linked-server results that are a product of non-determinism written into the SQL itself, I.e. a TOP query written without an ORDER BY clause.
This problem, for example, where the chap had multiple non-unique foreign keys coming from a table source on the left hand side of a linked-server INNER JOIN, and wanted 10 rows from a remote sub-query to the right, where the end result was restricted to 10 rows itself, when it should have been greater than 10 rows.
Should definitely give your SQL a quick eye for such curiosities.
The data on the linked server changed between executions?
Is your SQL Server fully patched? SQL Server 2008 and 2005 both have bug fixes out related to incorrect query results from linked servers.
Here is one example:
969997 FIX: You receive an incorrect result when you query data from a linked server that is created by using an index OLE DB provider in SQL Server 2005 or in SQL Server 2008
Is the linked server also a SQL Server? If not, perhaps a buggy driver? I've seen odd results, for example, due to an old Informix ODBC driver. Are you able to run something akin to SQL Profiler on the linked server to see what command it's receiving?
I'm not sure what the answer is, but (assuming that your counts of 100 and 120 are accurate) can you not capture the data from the two runs and compare it? That might give you some clues as to what's going on. For example, is it completely different datat, or is it duplicate rows (in the 120 row batch).

SQL Timeouts and SSIS

I've an SSIS package that runs a stored proc for exporting to an excel file. Everything worked like a champ until I needed to a do a bit of rewriting on the stored proc. The proc now takes about 1 minute to run and the exported columns are different, so my problems are the following;
1) SSIS complains when I hit the preview button "No column information returned by command"
2) It times out after about 30 seconds.
What I've done.
Tried to clean up/optimize the query. That helped a bit, but it still is doing some major calculations and it runs just fine in SSMS.
Changed the timeout values to 90 seconds. Didn't seem to help. Maybe someone here can?
Thanks,
Found this little tidbit which helped immensely.
No Column Names
Basically all you need to do is add the following to your SQL query text in SSIS.
SET FMTONLY OFF
SET NOCOUNT ON
Only problem now is it runs slow as molasses :-(
EDIT: It's running just too damn slow.
Changed from using #tempTable to tempTable. Adding in appropriate drop statements. argh...
Although it appears you may have answered part of your own question, you are probably getting the "No column information returned by command" error because the table doesn't exist at the time it tries to validate the metadata. Creating the tables as non-temporary tables resolves this issue.
If you insist on using temporary tables, you can create the temporary tables in the step preceeding the data flow. You would need to create it as a ## table and turn off connection sharing for the connection for this to work, but it is an alternative to creating permanent tables.
A shot in the dark based on something obscure I hit years ago: When you modified the procedure, did you add a call to a second procedure? This might mess up SSIS's ability to determine the returned data set.
As for (2), does the procedure take 30+ or 90+ seconds to run in SSMS? If not, do you know that the query is actually getting into SQL from SSIS? Might be worth firing up SQL Profiler to see what's actually being sent to SQL Server. [Which was the way I found out my obscure factoid.]