I have a database server that currently has two databases, call them [A] and [B].
[A] is the standard database used for my application
[B] is used by another application (that puts considerable load on the server), however, we use a few tables sparingly (that are shared between my application and the primary application that utilizes [B]). Recently the use of [B] has been increasing and it's causing long wait periods and timeouts in my application.
I'm open to alternative ideas, but at the moment the quickest potential solution I've come up with is to get a second database server and move [A] to that. However, I do need access to some of the tables in [B] - ideally with as little code changes as possible.
We were thinking a setup something like:
Current:
DB Server 1 {[A],[B]} (SQL Server 2005)
New Setup
DB Server 1 {[B]} (SQL Server 2005)
DB Server 2 {[A], [B]} (SQL Server 2008)
Where in the new setup, DBServer2.[B] is a linked table (kind of) to DBServer1.[B]
I looked into linked databases, from my understanding (limited) those work as an alias to a database on another server, which is almost what we want, except it adds the extra server qualifier, and it works on the db level. I'd like to do something like this, but ideally without the server qualifier and on a table level.
So for example, [B] has tables Users and Events. The Users table is updated weekly by batch, and we use it often, so we'd like to have a local copy on the new DBServer2. However, Events we use far less often and needs to be real-time between the two servers. In this case, it would be great to have Events as a linked table.
Further, it would be fantastic if we could use the same markup for queries. Today to query one db from the other we'd do something like
select * from b.events join a.dates
We'd like to continue that, except have the database server know that when we touch events it's really located at dbserver1.b.events.
Does that make sense? I confuse myself sometimes.
Thanks for any help
~P
You can use synonyms for linked objects - http://msdn.microsoft.com/en-us/library/ms177544%28SQL.90%29.aspx
This unfortunately only works for single objects, you CANNOT make a synonym for linkedserver.databasename and then reference synDBName.table.
"Alternative Idea" from me since you said you are open...
How about looking into the cause of the slowness? What is the "Load" you are measuring?
How are your disks laid out on the server?
Maybe you could use more memory, another CPU or Some SQL tuning?
Fixing your issues with a software or hardware fix MAY be faster than getting a server and doing all the installs and then working through the integration problems you may run into.
Related
Is there a way to detect which columns and which tables are used in a SQL Server database?
Just against SQL Server 2012 would be fine.
We can assume there are no '*' for column usage in the legacy site.
Details:
I'm working on updating the table structure of a legacy system to work on a newer database (2005 to 2012)
There are a lot of bloated tables, with columns that are never used, and even tables that are never used. Identifying all of them would be a pain by manually going through the code.
(My assumption is that we can run SQL Server profiler while running a complete test pass on the app, but I don't know a convenient way to extract the columns)
Thanks.
You can list dependencies for a table in Mgmt Studio, which will show you which SPs, UDFs etc depend on the table in question. You can't do that for a single field. However, that would only show the internal dependencies. Sql Profiler would theoretically show you all fields that get requested by your app however it still would not really tell you much as the app may not do anything with the values it retrieves. If you are going to change the db it would only really make sense to put in the effort if you were also going to change the app and then you should be really get some input from users on what features are still useful and what is broken before you get too involved in a back-end refresh. IMHO.
We have an AS400 mainframe running our DB2 transactional database. We also have a SQL Server setup that gets loaded nightly with data from the AS400. The SQL Server setup is for reporting.
I can link the two database servers, BUT, there's concern about how big a performance hit DB2 might suffer from queries coming from SQL Server.
Basically, the fear is that if we start hitting DB2 with queries from SQL Server we'll bog down the transactional system and screw up orders and shipping.
Thanks in advance for any knowledge that can be shared.
Anyone who has a pat answer for a performance question is wrong :-) The appropriate answer is always 'it depends.' Performance tuning is best done via measure, change one variable, repeat.
DB2 for i shouldn't even notice if someone executes a 1,000 row SELECT statement. Take Benny's suggestion and run one while the IBM i side watch. If they want a hint, use WRKACTJOB and sort on the Int column. That represents the interactive response time. I'd guess that the query will be complete before they have time to notice that it was active.
If that seems unacceptable to the management, then perhaps offer to test it before or after hours, where it can't possibly impact interactive performance.
As an aside, the RPG guys can create Excel spreadsheets on the fly too. Scott Klement published some RPG wrappers over the Java POI/HSSF classes. Also, Giovanni Perrotti at Easy400.net has some examples of providing an Excel spreadsheet from a web page.
I'd mostly agree with Buck, a 1000 row result set is no big deal...
Unless of course the system is looking through billions of rows across hundreds of tables to get the 1000 rows you are interested in.
Assuming a useful index exists, 1000 rows shouldn't be a big deal. If you have IBM i Access for Windows installed, there's a component of System i Navigator called "Run SQL Scripts" that includes "Visual Explain" that provides a visual explanation of the query execution plan. View that you can ensure that an index is being used.
On key thing, make sure the work is being done on the i. When using a standard linked table MS SQL Server will attempt to pull back all the rows then do it's own "where".
select * from MYLINK.MYIBMI.MYLIB.MYTABE where MYKEYFLD = '00335';
Whereas this format sends the statement to the remote server for processing and just gets back the results:
select * from openquery(MYLINK, 'select * from mylib.mytable where MYKEYFLD = ''00335''');
Alternately, you could ask the i guys to build you a stored procedure that you can call to get back the results you are looking for. Personally, that's my preferred method.
Charles
Is it possible to build a generic query that verifies and if needed corrects a whole table schema?
Example:
On my dev machine i have a sql server with some tables. I, and others, make changes to the tables and sometimes misses to notify the others about them. :/
I want to build a query that reads the dev sql tables and creates a query that i can run one another sql server and updates that table there so that they are equal.
I cant drop the table and recreate it unfortunately. I dont want to change any of the data.
If this is to hard with sql syntax is there some tools that can do this for me? The sql tables are almost always on different machines and most likely i cant connect directly to them from the same place. So tha fixing/verifying needs to be done "offline".
Time is not of the essence, it can be a very slow query as long as it works.
update: I want to verify the sql schema and not the content of the table
update2: We are using SQL Server 2008 R2
It is possible, but not easy. This kind of tool is called a Data Dictionary, and you can write one yourself (see advice from the Database Programmer) or you can buy a commercial one, for example RedGate's SQL Compare.
I have users entering data in SharePoint (Running on SQL Server), but my application to view that data will be an Oracle Apex app running on Oracle, obviously. How do I have the data be pushed into the Oracle db automatically?
First off, are you sure that you need to replicate the data to Oracle? Oracle Heterogeneous Services allows you to create a database link in Oracle that connects to a non-Oracle database using ODBC (assuming you use the Transparent Gateway for ODBC which is free). Your APEX application could then query and report on data that is in SQL Server by issuing queries that run over the database link. Tim Hall has a good article (though it's a bit dated and some of the components have been renamed, the general approach is still the same) on configuring Heterogeneous Services.
If you do need to replicate the data, you can create materialized views in Oracle that query the objects in SQL Server using the database link you created with Heterogeneous Services and schedule those materialized views to refresh on a regular basis. The materialized views will need to do a complete refresh, though, which means that every row will need to be copied from SQL Server to Oracle every time there is a refresh. That generally limits the frequency with which you can realistically have refreshes happen. If you need the data to be replicated to the Oracle database and you need to send incremental changes so that the Oracle side doesn't lag too far behind, you can use Streams from a non-Oracle database to an Oracle database but that involves a lot more work.
In SQL Server you can setup linked servers that allow you to view data from other db's. You might see if Oracle has something similar, if not the same. Alternatively, you could use the sql's integration services to push the data over to an oracle table. Unfortunately I only know how to setup linked servers in SQL Server and I don't have a lot of experience with ssis to tell you how to do that, but those are the first two options I can think of that you might explore further.
Here's a link I found that might be helpful as well: http://www.dba-oracle.com/t_connecting_sql_server_oracle.htm
There's no way to do it "automatically" that I know of that will work across DBMS. ETL tools like Sql Server Integration Services might help but there's going to be a loading delay (as it will have to poll for changes). You could build some update triggers on the SharePoint database tables but that's going to turn into a support nightmare.
Simple situation. I've created an application which uses SQL Server as database. I could add a table to this database which contains the version number of my application, so my application can check if it's talking to the correct version of the database. But since there are no other settings that I store inside a database, this would mean that I would add a single table with a single field, which contains only one record.
What a waste of a good resource...
Is there another wat that I can tell the SQL Server database about the product version that it's linked to?
I'm not interested in the version of SQL Server itself but of the database that it's using.
(Btw, this applies to both SQL Server 2000 and 2005.)
If you're using SQL 2005 and up, you can store version info as an Extended Property of the database itself and query the sys.extended_properties view to get the info, eg :
sys.sp_addextendedproperty #name=N'CurrentDBVersion', #value=N'1.4.2'
SELECT Value FROM sys.extended_properties WHERE name = 'CurrentDBVersion' AND class_desc = 'DATABASE'
If SQL 2000, I think your only option is your own table with one row. The overhead is almost non-existent.
I'd go with the massive overhead of a varchar(5) field with a tinyint PK. It makes the most sense if you're talking about a product that already uses the SQL Server database.
You're worried about overhead on such a small part of the system, that it becomes negligible.
I would put the connection settings in the application or a config file that the application reads. Have the app check the version number in the connection settings.
Even if there was such a feature in SQL Server, I wouldn't use it. Why?
Adding a new table to store the information is negligible to both the size and speed of the application and database
A new table could store other configuration data related to the application, and you've already got a mechanism in place for it (and if your application is that large, you will have other configuration data)
Coupling the application to a specific database engine (especially this way) is very rarely a good thing
Not standard practice, and not obvious to someone new looking at the system for the first time
I highly recommend writing the data base version into the database.
In an application we maintained over a decade or so we had updates of the database schema every release.
When the user started the application after an update installation it could detect if the database was to old and convert it to the newer schema. We actually did an incremental update: In order to get from 7 to 10 we did 7 -> 8, 8->9, 9->10.
Also imagine the scenario when somebody restores the database to an older state from a backup.
Don't even think about adding a single table, just do it (and think about the use cases).