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  • What is the fastest method to create a new database from a template ?

    - by Locksfree
    We are creating databases on demand and the databases can be created from different templates. All templates have the same structure but different data. The data contained by the templates is small. What is the fastest way to create a copy of the database: Backup/Restore Using T-SQL ? Using SMO ? Create a new database from a scripted version of the template and then fill in the little data required ? Other ?

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  • How to convert an application to be a database independent app ?

    - by Eslam
    I have a java web application that has informix DB as it's back end database , now i take a decision to make my app work with SqlServer so i changed all the informix related syntax into SqlServer, and i may take a decision in the future to switch into oracle so the pain will be repeated again and again, as a result i decided to make my application a DataBase independent one that's able to work with any DB vendor smoothly, but i have no idea till now about how to do that, so your ideas is welcomed.

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  • How can I get the name of all tables in a JavaDB database?

    - by Jonas
    How can i programmatically get the names of all tables in a JavaDB database? Is there any specific SQL-statement over JDBC I can use for this or any built in function in JDBC? I will use it for exporting the tables to XML, and would like to do it this way so I don't miss any tables from the database when exporting.

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  • How to determine whether a database has been changed or not ?

    - by Locksfree
    I have a need to determine if a database on a MS SQL Server has changed between two distinct moments. The change can be structural or data-related and the check should be generic (i.e. independant of the structure of the database). Preferably, I'd like the check to be T-SQL based or with SMOs, not file based. I checked on MSDN but I haven't found anything relevant so far.

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  • Entity Framework - Single EMDX Mapping Multiple Database

    - by michaelalisonalviar
    Because of my recent craze on Entity Framework thanks to Sir Humprey, I have continuously searched the Internet for tutorials on how to apply it to our current system. So I've come to learn that with EF, I can eliminate the numerous coding of methods/functions for CRUD operations, my overly used assigning of connection strings, Data Adapters or Data Readers as Entity Framework will map my desired database and will do its magic to create entities for each table I want (using EF Powertool) and does all the methods/functions for my Crud Operations. But as I begin applying it to a new project I was assigned to, I realized our current server is designed to contain each similar entities in different databases. For example Our lookup tables are stored in LookupDb, Accounting-related tables are in AccountingDb, Sales-related tables in SalesDb. My dilemma is I have to use an existing table from LookupDB and use it as a look-up for my new table. Then I have found Miss Rachel's Blog (here)Thank You Miss Rachel!  which enables me to let EF think that my TableLookup1 is in the AccountingDB using the following steps. Im on VS 2010, I am using C# , Using Entity Framework 5, SQL Server 2008 as our DB ServerStep 1:Creating A SQL Synonym. If you want a more detailed discussion on synonyms, this was what i have read -> (link here). To simply put it, A synonym enabled me to simplify my query for the Look-up table when I'm using the AccountingDB fromSELECT [columns] FROM LookupDB.dbo.TableLookup1toSELECT [columns] FROM TableLookup1Syntax: CREATE SYNONYM  TableLookup1(1) FOR LookupDB.dbo.TableLookup1 (2)1. What you want to call the table on your other DB2. DataBaseName.schema.TableNameStep 2: We will now follow Miss Rachel's steps. you can either visit the link on the original topic I posted earlier or just follow the step I made.1. I created a Visual Basic Solution that will contain the 4 projects needed to complete the merging2. First project will contain the edmx file pointing to the AccountingDB3. Second project will contain the edmx file pointing to the LookupDB4. Third Project will will be our repository of the merged edmx file. Create an edmx file pointing To AccountingDB as this the database that we created the Synonym on.Reminder: Aside from using the same name for the Entities, please make sure that you have the same Model Namespace for all your Entities  5. Fourth project that will contain the beautiful EDMX merger that Miss Rachel created that will free you from Hard coding of the merge/recoding the Edmx File of the third project everytime a change is done on either one of the first two projects' Edmx File.6. Run the solution, but make sure that on the solutions properties Single startup project is selected and the project containing the EDMX merger is selected.7. After running the solution, double click on the EDMX file of the 3rd project and set Lazy Loading Enabled = False. This will let you use the tables/entities that you see in that EDMX File.8. Feel free to do your CRUD Operations.I don't know if EF 5 already has a feature to support synonyms as I am still a newbie on that aspect but I have seen a linked where there are supposed suggestions on Entity Framework upgrades and one is the "Support for multiple databases"  So that's it! Thanks for reading!

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  • "database already closed" is shown using a custom cursor adapter

    - by kiduxa
    I'm using a cursor with a custom adapter that extends SimpleCursorAdapter: public class ListWordAdapter extends SimpleCursorAdapter { private LayoutInflater inflater; private Cursor mCursor; private int mLayout; private String[] from; private int[] to; public ListWordAdapter(Context context, int layout, Cursor c, String[] from, int[] to, int flags) { super(context, layout, c, from, to, flags); this.mCursor = c; this.inflater = LayoutInflater.from(context); this.mLayout = layout; this.from = from; this.to = to; } private static class ViewHolder { //public ImageView img; public TextView name; public TextView type; public TextView translate; } @Override public View getView(int position, View convertView, ViewGroup parent) { if (mCursor.moveToPosition(position)) { ViewHolder holder; if (convertView == null) { convertView = inflater.inflate(mLayout, null); holder = new ViewHolder(); // holder.img = (ImageView) convertView.findViewById(R.id.img_row); holder.name = (TextView) convertView.findViewById(to[0]); holder.type = (TextView) convertView.findViewById(to[1]); holder.translate = (TextView) convertView.findViewById(to[2]); convertView.setTag(holder); } else { holder = (ViewHolder) convertView.getTag(); } holder.name.setText(mCursor.getString(mCursor.getColumnIndex(from[0]))); holder.type.setText(mCursor.getString(mCursor.getColumnIndex(from[1]))); holder.translate.setText(mCursor.getString(mCursor.getColumnIndex(from[2]))); // holder.img.setImageResource(img_resource); } return convertView; } } And in the main activity I call it as: adapter = new ListWordAdapter(getSherlockActivity(), R.layout.row_list_words, mCursorWords, from, to, 0); When a modification in the list is made, I call this method: public void onWordSaved() { WordDAO wordsDao = new WordSqliteDAO(); Cursor mCursorWords = wordsDao.list(getSherlockActivity()); adapter.changeCursor(mCursorWords); } The thing here is that this produces me this exception: 10-29 11:14:33.810: E/AndroidRuntime(18659): java.lang.IllegalStateException: database /data/data/com.example.palabrasdeldia/databases/palabrasDelDia (conn# 0) already closed Complete stack trace: 10-29 11:14:33.810: E/AndroidRuntime(18659): FATAL EXCEPTION: main 10-29 11:14:33.810: E/AndroidRuntime(18659): java.lang.IllegalStateException: database /data/data/com.example.palabrasdeldia/databases/palabrasDelDia (conn# 0) already closed 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.database.sqlite.SQLiteDatabase.verifyDbIsOpen(SQLiteDatabase.java:2123) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.database.sqlite.SQLiteDatabase.lock(SQLiteDatabase.java:398) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.database.sqlite.SQLiteDatabase.lock(SQLiteDatabase.java:390) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.database.sqlite.SQLiteQuery.fillWindow(SQLiteQuery.java:74) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.database.sqlite.SQLiteCursor.fillWindow(SQLiteCursor.java:311) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.database.sqlite.SQLiteCursor.onMove(SQLiteCursor.java:283) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.database.AbstractCursor.moveToPosition(AbstractCursor.java:173) 10-29 11:14:33.810: E/AndroidRuntime(18659): at com.example.palabrasdeldia.adapters.ListWordAdapter.getView(ListWordAdapter.java:42) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.widget.AbsListView.obtainView(AbsListView.java:2128) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.widget.ListView.makeAndAddView(ListView.java:1817) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.widget.ListView.fillSpecific(ListView.java:1361) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.widget.ListView.layoutChildren(ListView.java:1646) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.widget.AbsListView.onLayout(AbsListView.java:1979) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.view.View.layout(View.java:9593) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.view.ViewGroup.layout(ViewGroup.java:3877) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1542) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.widget.LinearLayout.layoutHorizontal(LinearLayout.java:1527) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.widget.LinearLayout.onLayout(LinearLayout.java:1316) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.view.View.layout(View.java:9593) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.view.ViewGroup.layout(ViewGroup.java:3877) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.widget.FrameLayout.onLayout(FrameLayout.java:400) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.view.View.layout(View.java:9593) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.view.ViewGroup.layout(ViewGroup.java:3877) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.support.v4.view.ViewPager.onLayout(ViewPager.java:1589) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.view.View.layout(View.java:9593) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.view.ViewGroup.layout(ViewGroup.java:3877) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.widget.FrameLayout.onLayout(FrameLayout.java:400) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.view.View.layout(View.java:9593) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.view.ViewGroup.layout(ViewGroup.java:3877) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1542) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1403) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.widget.LinearLayout.onLayout(LinearLayout.java:1314) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.view.View.layout(View.java:9593) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.view.ViewGroup.layout(ViewGroup.java:3877) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.widget.FrameLayout.onLayout(FrameLayout.java:400) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.view.View.layout(View.java:9593) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.view.ViewGroup.layout(ViewGroup.java:3877) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1542) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1403) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.widget.LinearLayout.onLayout(LinearLayout.java:1314) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.view.View.layout(View.java:9593) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.view.ViewGroup.layout(ViewGroup.java:3877) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.widget.FrameLayout.onLayout(FrameLayout.java:400) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.view.View.layout(View.java:9593) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.view.ViewGroup.layout(ViewGroup.java:3877) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.widget.FrameLayout.onLayout(FrameLayout.java:400) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.view.View.layout(View.java:9593) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.view.ViewGroup.layout(ViewGroup.java:3877) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.view.ViewRoot.performTraversals(ViewRoot.java:1253) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.view.ViewRoot.handleMessage(ViewRoot.java:2017) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.os.Handler.dispatchMessage(Handler.java:99) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.os.Looper.loop(Looper.java:132) 10-29 11:14:33.810: E/AndroidRuntime(18659): at android.app.ActivityThread.main(ActivityThread.java:4028) 10-29 11:14:33.810: E/AndroidRuntime(18659): at java.lang.reflect.Method.invokeNative(Native Method) 10-29 11:14:33.810: E/AndroidRuntime(18659): at java.lang.reflect.Method.invoke(Method.java:491) 10-29 11:14:33.810: E/AndroidRuntime(18659): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:844) 10-29 11:14:33.810: E/AndroidRuntime(18659): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:602) 10-29 11:14:33.810: E/AndroidRuntime(18659): at dalvik.system.NativeStart.main(Native Method) If I use SimpleCursorAdapter directly instead of ListWordAdapter, it works fine. What's wrong with my custom adapter implementation? The line in bold in the stack trace corresponds with: if (mCursor.moveToPosition(position)) inside getView method. EDIT: I have created a custom class to manage DB operations as open and close: public class ConexionBD { private Context context; private SQLiteDatabase database; private DataBaseHelper dbHelper; public ConexionBD(Context context) { this.context = context; } public ConexionBD open() throws SQLException { this.dbHelper = DataBaseHelper.getInstance(context); this.database = dbHelper.getWritableDatabase(); database.execSQL("PRAGMA foreign_keys=ON"); return this; } public void close() { if (database.isOpen() && database != null) { dbHelper.close(); } } /*Getters y setters*/ public SQLiteDatabase getDatabase() { return database; } public void setDatabase(SQLiteDatabase database) { this.database = database; } } And this is my DataBaseHelper: public class DataBaseHelper extends SQLiteOpenHelper { private static final String DATABASE_NAME = "myDb"; private static final int DATABASE_VERSION = 1; private static DataBaseHelper sInstance = null; public static DataBaseHelper getInstance(Context context) { // Use the application context, which will ensure that you // don't accidentally leak an Activity's context. // See this article for more information: http://bit.ly/6LRzfx if (sInstance == null) { sInstance = new DataBaseHelper(context.getApplicationContext()); } return sInstance; } @Override public void onCreate(SQLiteDatabase database) { ... } .... And this is an example of how I manage a query: public Cursor list(Context context) { ConexionBD conexion = new ConexionBD(context); Cursor mCursor = null; try{ conexion.open(); mCursor = conexion.getDatabase().query(DataBaseHelper.TABLE_WORD , null , null, null, null, null, Word.NAME); if (mCursor != null) { mCursor.moveToFirst(); } }finally{ conexion.close(); } return mCursor; } For every connection to the DB I open it and close it.

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  • Plan Caching and Query Memory Part II (Hash Match) – When not to use stored procedure - Most common performance mistake SQL Server developers make.

    - by sqlworkshops
    SQL Server estimates Memory requirement at compile time, when stored procedure or other plan caching mechanisms like sp_executesql or prepared statement are used, the memory requirement is estimated based on first set of execution parameters. This is a common reason for spill over tempdb and hence poor performance. Common memory allocating queries are that perform Sort and do Hash Match operations like Hash Join or Hash Aggregation or Hash Union. This article covers Hash Match operations with examples. It is recommended to read Plan Caching and Query Memory Part I before this article which covers an introduction and Query memory for Sort. In most cases it is cheaper to pay for the compilation cost of dynamic queries than huge cost for spill over tempdb, unless memory requirement for a query does not change significantly based on predicates.   This article covers underestimation / overestimation of memory for Hash Match operation. Plan Caching and Query Memory Part I covers underestimation / overestimation for Sort. It is important to note that underestimation of memory for Sort and Hash Match operations lead to spill over tempdb and hence negatively impact performance. Overestimation of memory affects the memory needs of other concurrently executing queries. In addition, it is important to note, with Hash Match operations, overestimation of memory can actually lead to poor performance.   To read additional articles I wrote click here.   The best way to learn is to practice. To create the below tables and reproduce the behavior, join the mailing list by using this link: www.sqlworkshops.com/ml and I will send you the table creation script. Most of these concepts are also covered in our webcasts: www.sqlworkshops.com/webcasts  Let’s create a Customer’s State table that has 99% of customers in NY and the rest 1% in WA.Customers table used in Part I of this article is also used here.To observe Hash Warning, enable 'Hash Warning' in SQL Profiler under Events 'Errors and Warnings'. --Example provided by www.sqlworkshops.com drop table CustomersState go create table CustomersState (CustomerID int primary key, Address char(200), State char(2)) go insert into CustomersState (CustomerID, Address) select CustomerID, 'Address' from Customers update CustomersState set State = 'NY' where CustomerID % 100 != 1 update CustomersState set State = 'WA' where CustomerID % 100 = 1 go update statistics CustomersState with fullscan go   Let’s create a stored procedure that joins customers with CustomersState table with a predicate on State. --Example provided by www.sqlworkshops.com create proc CustomersByState @State char(2) as begin declare @CustomerID int select @CustomerID = e.CustomerID from Customers e inner join CustomersState es on (e.CustomerID = es.CustomerID) where es.State = @State option (maxdop 1) end go  Let’s execute the stored procedure first with parameter value ‘WA’ – which will select 1% of data. set statistics time on go --Example provided by www.sqlworkshops.com exec CustomersByState 'WA' goThe stored procedure took 294 ms to complete.  The stored procedure was granted 6704 KB based on 8000 rows being estimated.  The estimated number of rows, 8000 is similar to actual number of rows 8000 and hence the memory estimation should be ok.  There was no Hash Warning in SQL Profiler. To observe Hash Warning, enable 'Hash Warning' in SQL Profiler under Events 'Errors and Warnings'.   Now let’s execute the stored procedure with parameter value ‘NY’ – which will select 99% of data. -Example provided by www.sqlworkshops.com exec CustomersByState 'NY' go  The stored procedure took 2922 ms to complete.   The stored procedure was granted 6704 KB based on 8000 rows being estimated.    The estimated number of rows, 8000 is way different from the actual number of rows 792000 because the estimation is based on the first set of parameter value supplied to the stored procedure which is ‘WA’ in our case. This underestimation will lead to spill over tempdb, resulting in poor performance.   There was Hash Warning (Recursion) in SQL Profiler. To observe Hash Warning, enable 'Hash Warning' in SQL Profiler under Events 'Errors and Warnings'.   Let’s recompile the stored procedure and then let’s first execute the stored procedure with parameter value ‘NY’.  In a production instance it is not advisable to use sp_recompile instead one should use DBCC FREEPROCCACHE (plan_handle). This is due to locking issues involved with sp_recompile, refer to our webcasts, www.sqlworkshops.com/webcasts for further details.   exec sp_recompile CustomersByState go --Example provided by www.sqlworkshops.com exec CustomersByState 'NY' go  Now the stored procedure took only 1046 ms instead of 2922 ms.   The stored procedure was granted 146752 KB of memory. The estimated number of rows, 792000 is similar to actual number of rows of 792000. Better performance of this stored procedure execution is due to better estimation of memory and avoiding spill over tempdb.   There was no Hash Warning in SQL Profiler.   Now let’s execute the stored procedure with parameter value ‘WA’. --Example provided by www.sqlworkshops.com exec CustomersByState 'WA' go  The stored procedure took 351 ms to complete, higher than the previous execution time of 294 ms.    This stored procedure was granted more memory (146752 KB) than necessary (6704 KB) based on parameter value ‘NY’ for estimation (792000 rows) instead of parameter value ‘WA’ for estimation (8000 rows). This is because the estimation is based on the first set of parameter value supplied to the stored procedure which is ‘NY’ in this case. This overestimation leads to poor performance of this Hash Match operation, it might also affect the performance of other concurrently executing queries requiring memory and hence overestimation is not recommended.     The estimated number of rows, 792000 is much more than the actual number of rows of 8000.  Intermediate Summary: This issue can be avoided by not caching the plan for memory allocating queries. Other possibility is to use recompile hint or optimize for hint to allocate memory for predefined data range.Let’s recreate the stored procedure with recompile hint. --Example provided by www.sqlworkshops.com drop proc CustomersByState go create proc CustomersByState @State char(2) as begin declare @CustomerID int select @CustomerID = e.CustomerID from Customers e inner join CustomersState es on (e.CustomerID = es.CustomerID) where es.State = @State option (maxdop 1, recompile) end go  Let’s execute the stored procedure initially with parameter value ‘WA’ and then with parameter value ‘NY’. --Example provided by www.sqlworkshops.com exec CustomersByState 'WA' go exec CustomersByState 'NY' go  The stored procedure took 297 ms and 1102 ms in line with previous optimal execution times.   The stored procedure with parameter value ‘WA’ has good estimation like before.   Estimated number of rows of 8000 is similar to actual number of rows of 8000.   The stored procedure with parameter value ‘NY’ also has good estimation and memory grant like before because the stored procedure was recompiled with current set of parameter values.  Estimated number of rows of 792000 is similar to actual number of rows of 792000.    The compilation time and compilation CPU of 1 ms is not expensive in this case compared to the performance benefit.   There was no Hash Warning in SQL Profiler.   Let’s recreate the stored procedure with optimize for hint of ‘NY’. --Example provided by www.sqlworkshops.com drop proc CustomersByState go create proc CustomersByState @State char(2) as begin declare @CustomerID int select @CustomerID = e.CustomerID from Customers e inner join CustomersState es on (e.CustomerID = es.CustomerID) where es.State = @State option (maxdop 1, optimize for (@State = 'NY')) end go  Let’s execute the stored procedure initially with parameter value ‘WA’ and then with parameter value ‘NY’. --Example provided by www.sqlworkshops.com exec CustomersByState 'WA' go exec CustomersByState 'NY' go  The stored procedure took 353 ms with parameter value ‘WA’, this is much slower than the optimal execution time of 294 ms we observed previously. This is because of overestimation of memory. The stored procedure with parameter value ‘NY’ has optimal execution time like before.   The stored procedure with parameter value ‘WA’ has overestimation of rows because of optimize for hint value of ‘NY’.   Unlike before, more memory was estimated to this stored procedure based on optimize for hint value ‘NY’.    The stored procedure with parameter value ‘NY’ has good estimation because of optimize for hint value of ‘NY’. Estimated number of rows of 792000 is similar to actual number of rows of 792000.   Optimal amount memory was estimated to this stored procedure based on optimize for hint value ‘NY’.   There was no Hash Warning in SQL Profiler.   This article covers underestimation / overestimation of memory for Hash Match operation. Plan Caching and Query Memory Part I covers underestimation / overestimation for Sort. It is important to note that underestimation of memory for Sort and Hash Match operations lead to spill over tempdb and hence negatively impact performance. Overestimation of memory affects the memory needs of other concurrently executing queries. In addition, it is important to note, with Hash Match operations, overestimation of memory can actually lead to poor performance.   Summary: Cached plan might lead to underestimation or overestimation of memory because the memory is estimated based on first set of execution parameters. It is recommended not to cache the plan if the amount of memory required to execute the stored procedure has a wide range of possibilities. One can mitigate this by using recompile hint, but that will lead to compilation overhead. However, in most cases it might be ok to pay for compilation rather than spilling sort over tempdb which could be very expensive compared to compilation cost. The other possibility is to use optimize for hint, but in case one sorts more data than hinted by optimize for hint, this will still lead to spill. On the other side there is also the possibility of overestimation leading to unnecessary memory issues for other concurrently executing queries. In case of Hash Match operations, this overestimation of memory might lead to poor performance. When the values used in optimize for hint are archived from the database, the estimation will be wrong leading to worst performance, so one has to exercise caution before using optimize for hint, recompile hint is better in this case.   I explain these concepts with detailed examples in my webcasts (www.sqlworkshops.com/webcasts), I recommend you to watch them. The best way to learn is to practice. To create the above tables and reproduce the behavior, join the mailing list at www.sqlworkshops.com/ml and I will send you the relevant SQL Scripts.  Register for the upcoming 3 Day Level 400 Microsoft SQL Server 2008 and SQL Server 2005 Performance Monitoring & Tuning Hands-on Workshop in London, United Kingdom during March 15-17, 2011, click here to register / Microsoft UK TechNet.These are hands-on workshops with a maximum of 12 participants and not lectures. For consulting engagements click here.   Disclaimer and copyright information:This article refers to organizations and products that may be the trademarks or registered trademarks of their various owners. Copyright of this article belongs to R Meyyappan / www.sqlworkshops.com. You may freely use the ideas and concepts discussed in this article with acknowledgement (www.sqlworkshops.com), but you may not claim any of it as your own work. This article is for informational purposes only; you use any of the suggestions given here entirely at your own risk.   R Meyyappan [email protected] LinkedIn: http://at.linkedin.com/in/rmeyyappan

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  • ?Oracle Database 12c????Information Lifecycle Management ILM?Storage Enhancements

    - by Liu Maclean(???)
    Oracle Database 12c????Information Lifecycle Management ILM ?????????Storage Enhancements ???????? Lifecycle Management ILM ????????? Automatic Data Placement ??????, ??ADP? ?????? 12c???????Datafile??? Online Move Datafile, ????????????????datafile???????,??????????????? ????(12.1.0.1)Automatic Data Optimization?heat map????????: ????????? (CDB)?????Automatic Data Optimization?heat map Row-level policies for ADO are not supported for Temporal Validity. Partition-level ADO and compression are supported if partitioned on the end-time columns. Row-level policies for ADO are not supported for in-database archiving. Partition-level ADO and compression are supported if partitioned on the ORA_ARCHIVE_STATE column. Custom policies (user-defined functions) for ADO are not supported if the policies default at the tablespace level. ADO does not perform checks for storage space in a target tablespace when using storage tiering. ADO is not supported on tables with object types or materialized views. ADO concurrency (the number of simultaneous policy jobs for ADO) depends on the concurrency of the Oracle scheduler. If a policy job for ADO fails more than two times, then the job is marked disabled and the job must be manually enabled later. Policies for ADO are only run in the Oracle Scheduler maintenance windows. Outside of the maintenance windows all policies are stopped. The only exceptions are those jobs for rebuilding indexes in ADO offline mode. ADO has restrictions related to moving tables and table partitions. ??????row,segment???????????ADO??,?????create table?alter table?????? ????ADO??,??????????????,???????????????? storage tier , ?????????storage tier?????????, ??????????????ADO??????????? segment?row??group? ?CREATE TABLE?ALERT TABLE???ILM???,??????????????????ADO policy? ??ILM policy???????????????? ??????? ????ADO policy, ?????alter table  ???????,?????????????? CREATE TABLE sales_ado (PROD_ID NUMBER NOT NULL, CUST_ID NUMBER NOT NULL, TIME_ID DATE NOT NULL, CHANNEL_ID NUMBER NOT NULL, PROMO_ID NUMBER NOT NULL, QUANTITY_SOLD NUMBER(10,2) NOT NULL, AMOUNT_SOLD NUMBER(10,2) NOT NULL ) ILM ADD POLICY COMPRESS FOR ARCHIVE HIGH SEGMENT AFTER 6 MONTHS OF NO ACCESS; SQL> SELECT SUBSTR(policy_name,1,24) AS POLICY_NAME, policy_type, enabled 2 FROM USER_ILMPOLICIES; POLICY_NAME POLICY_TYPE ENABLED -------------------- -------------------------- -------------- P41 DATA MOVEMENT YES ALTER TABLE sales MODIFY PARTITION sales_1995 ILM ADD POLICY COMPRESS FOR ARCHIVE HIGH SEGMENT AFTER 6 MONTHS OF NO ACCESS; SELECT SUBSTR(policy_name,1,24) AS POLICY_NAME, policy_type, enabled FROM USER_ILMPOLICIES; POLICY_NAME POLICY_TYPE ENABLE ------------------------ ------------- ------ P1 DATA MOVEMENT YES P2 DATA MOVEMENT YES /* You can disable an ADO policy with the following */ ALTER TABLE sales_ado ILM DISABLE POLICY P1; /* You can delete an ADO policy with the following */ ALTER TABLE sales_ado ILM DELETE POLICY P1; /* You can disable all ADO policies with the following */ ALTER TABLE sales_ado ILM DISABLE_ALL; /* You can delete all ADO policies with the following */ ALTER TABLE sales_ado ILM DELETE_ALL; /* You can disable an ADO policy in a partition with the following */ ALTER TABLE sales MODIFY PARTITION sales_1995 ILM DISABLE POLICY P2; /* You can delete an ADO policy in a partition with the following */ ALTER TABLE sales MODIFY PARTITION sales_1995 ILM DELETE POLICY P2; ILM ???????: ?????ILM ADP????,???????: ?????? ???? activity tracking, ????2????????,???????????????????: SEGMENT-LEVEL???????????????????? ROW-LEVEL????????,??????? ????????: 1??????? SEGMENT-LEVEL activity tracking ALTER TABLE interval_sales ILM  ENABLE ACTIVITY TRACKING SEGMENT ACCESS ???????INTERVAL_SALES??segment level  activity tracking,?????????????????? 2? ??????????? ALTER TABLE emp ILM ENABLE ACTIVITY TRACKING (CREATE TIME , WRITE TIME); 3????????? ALTER TABLE emp ILM ENABLE ACTIVITY TRACKING  (READ TIME); ?12.1.0.1.0?????? ??HEAT_MAP??????????, ?????system??session?????heap_map????????????? ?????????HEAT MAP??,? ALTER SYSTEM SET HEAT_MAP = ON; ?HEAT MAP??????,??????????????????????????  ??SYSTEM?SYSAUX????????????? ???????HEAT MAP??: ALTER SYSTEM SET HEAT_MAP = OFF; ????? HEAT_MAP????, ?HEAT_MAP??? ?????????????????????? ?HEAT_MAP?????????Automatic Data Optimization (ADO)??? ??ADO??,Heat Map ?????????? ????V$HEAT_MAP_SEGMENT ??????? HEAT MAP?? SQL> select * from V$heat_map_segment; no rows selected SQL> alter session set heat_map=on; Session altered. SQL> select * from scott.emp; EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO ---------- ---------- --------- ---------- --------- ---------- ---------- ---------- 7369 SMITH CLERK 7902 17-DEC-80 800 20 7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 30 7521 WARD SALESMAN 7698 22-FEB-81 1250 500 30 7566 JONES MANAGER 7839 02-APR-81 2975 20 7654 MARTIN SALESMAN 7698 28-SEP-81 1250 1400 30 7698 BLAKE MANAGER 7839 01-MAY-81 2850 30 7782 CLARK MANAGER 7839 09-JUN-81 2450 10 7788 SCOTT ANALYST 7566 19-APR-87 3000 20 7839 KING PRESIDENT 17-NOV-81 5000 10 7844 TURNER SALESMAN 7698 08-SEP-81 1500 0 30 7876 ADAMS CLERK 7788 23-MAY-87 1100 20 7900 JAMES CLERK 7698 03-DEC-81 950 30 7902 FORD ANALYST 7566 03-DEC-81 3000 20 7934 MILLER CLERK 7782 23-JAN-82 1300 10 14 rows selected. SQL> select * from v$heat_map_segment; OBJECT_NAME SUBOBJECT_NAME OBJ# DATAOBJ# TRACK_TIM SEG SEG FUL LOO CON_ID -------------------- -------------------- ---------- ---------- --------- --- --- --- --- ---------- EMP 92997 92997 23-JUL-13 NO NO YES NO 0 ??v$heat_map_segment???,?v$heat_map_segment??????????????X$HEATMAPSEGMENT V$HEAT_MAP_SEGMENT displays real-time segment access information. Column Datatype Description OBJECT_NAME VARCHAR2(128) Name of the object SUBOBJECT_NAME VARCHAR2(128) Name of the subobject OBJ# NUMBER Object number DATAOBJ# NUMBER Data object number TRACK_TIME DATE Timestamp of current activity tracking SEGMENT_WRITE VARCHAR2(3) Indicates whether the segment has write access: (YES or NO) SEGMENT_READ VARCHAR2(3) Indicates whether the segment has read access: (YES or NO) FULL_SCAN VARCHAR2(3) Indicates whether the segment has full table scan: (YES or NO) LOOKUP_SCAN VARCHAR2(3) Indicates whether the segment has lookup scan: (YES or NO) CON_ID NUMBER The ID of the container to which the data pertains. Possible values include:   0: This value is used for rows containing data that pertain to the entire CDB. This value is also used for rows in non-CDBs. 1: This value is used for rows containing data that pertain to only the root n: Where n is the applicable container ID for the rows containing data The Heat Map feature is not supported in CDBs in Oracle Database 12c, so the value in this column can be ignored. ??HEAP MAP??????????????????,????DBA_HEAT_MAP_SEGMENT???????? ???????HEAT_MAP_STAT$?????? ??Automatic Data Optimization??????: ????1: SQL> alter system set heat_map=on; ?????? ????????????? scott?? http://www.askmaclean.com/archives/scott-schema-script.html SQL> grant all on dbms_lock to scott; ????? SQL> grant dba to scott; ????? @ilm_setup_basic C:\APP\XIANGBLI\ORADATA\MACLEAN\ilm.dbf @tktgilm_demo_env_setup SQL> connect scott/tiger ; ???? SQL> select count(*) from scott.employee; COUNT(*) ---------- 3072 ??? 1 ?? SQL> set serveroutput on SQL> exec print_compression_stats('SCOTT','EMPLOYEE'); Compression Stats ------------------ Uncmpressed : 3072 Adv/basic compressed : 0 Others : 0 PL/SQL ???????? ???????3072?????? ????????? ????policy ???????????? alter table employee ilm add policy row store compress advanced row after 3 days of no modification / SQL> set serveroutput on SQL> execute list_ilm_policies; -------------------------------------------------- Policies defined for SCOTT -------------------------------------------------- Object Name------ : EMPLOYEE Subobject Name--- : Object Type------ : TABLE Inherited from--- : POLICY NOT INHERITED Policy Name------ : P1 Action Type------ : COMPRESSION Scope------------ : ROW Compression level : ADVANCED Tier Tablespace-- : Condition type--- : LAST MODIFICATION TIME Condition days--- : 3 Enabled---------- : YES -------------------------------------------------- PL/SQL ???????? SQL> select sysdate from dual; SYSDATE -------------- 29-7? -13 SQL> execute set_back_chktime(get_policy_name('EMPLOYEE',null,'COMPRESSION','ROW','ADVANCED',3,null,null),'EMPLOYEE',null,6); Object check time reset ... -------------------------------------- Object Name : EMPLOYEE Object Number : 93123 D.Object Numbr : 93123 Policy Number : 1 Object chktime : 23-7? -13 08.13.42.000000 ?? Distnt chktime : 0 -------------------------------------- PL/SQL ???????? ?policy?chktime???6??, ????set_back_chktime???????????????“????”?,?????????,???????? ?????? alter system flush buffer_cache; alter system flush buffer_cache; alter system flush shared_pool; alter system flush shared_pool; SQL> execute set_window('MONDAY_WINDOW','OPEN'); Set Maint. Window OPEN ----------------------------- Window Name : MONDAY_WINDOW Enabled? : TRUE Active? : TRUE ----------------------------- PL/SQL ???????? SQL> exec dbms_lock.sleep(60) ; PL/SQL ???????? SQL> exec print_compression_stats('SCOTT', 'EMPLOYEE'); Compression Stats ------------------ Uncmpressed : 338 Adv/basic compressed : 2734 Others : 0 PL/SQL ???????? ??????????????? Adv/basic compressed : 2734 ??????? SQL> col object_name for a20 SQL> select object_id,object_name from dba_objects where object_name='EMPLOYEE'; OBJECT_ID OBJECT_NAME ---------- -------------------- 93123 EMPLOYEE SQL> execute list_ilm_policy_executions ; -------------------------------------------------- Policies execution details for SCOTT -------------------------------------------------- Policy Name------ : P22 Job Name--------- : ILMJOB48 Start time------- : 29-7? -13 08.37.45.061000 ?? End time--------- : 29-7? -13 08.37.48.629000 ?? ----------------- Object Name------ : EMPLOYEE Sub_obj Name----- : Obj Type--------- : TABLE ----------------- Exec-state------- : SELECTED FOR EXECUTION Job state-------- : COMPLETED SUCCESSFULLY Exec comments---- : Results comments- : --- -------------------------------------------------- PL/SQL ???????? ILMJOB48?????policy?JOB,?12.1.0.1??J00x???? ?MMON_SLAVE???M00x???15????????? select sample_time,program,module,action from v$active_session_history where action ='KDILM background EXEcution' order by sample_time; 29-7? -13 08.16.38.369000000 ?? ORACLE.EXE (M000) MMON_SLAVE KDILM background EXEcution 29-7? -13 08.17.38.388000000 ?? ORACLE.EXE (M000) MMON_SLAVE KDILM background EXEcution 29-7? -13 08.17.39.390000000 ?? ORACLE.EXE (M000) MMON_SLAVE KDILM background EXEcution 29-7? -13 08.23.38.681000000 ?? ORACLE.EXE (M002) MMON_SLAVE KDILM background EXEcution 29-7? -13 08.32.38.968000000 ?? ORACLE.EXE (M000) MMON_SLAVE KDILM background EXEcution 29-7? -13 08.33.39.993000000 ?? ORACLE.EXE (M003) MMON_SLAVE KDILM background EXEcution 29-7? -13 08.33.40.993000000 ?? ORACLE.EXE (M003) MMON_SLAVE KDILM background EXEcution 29-7? -13 08.36.40.066000000 ?? ORACLE.EXE (M000) MMON_SLAVE KDILM background EXEcution 29-7? -13 08.37.42.258000000 ?? ORACLE.EXE (M000) MMON_SLAVE KDILM background EXEcution 29-7? -13 08.37.43.258000000 ?? ORACLE.EXE (M000) MMON_SLAVE KDILM background EXEcution 29-7? -13 08.37.44.258000000 ?? ORACLE.EXE (M000) MMON_SLAVE KDILM background EXEcution 29-7? -13 08.38.42.386000000 ?? ORACLE.EXE (M001) MMON_SLAVE KDILM background EXEcution select distinct action from v$active_session_history where action like 'KDILM%' KDILM background CLeaNup KDILM background EXEcution SQL> execute set_window('MONDAY_WINDOW','CLOSE'); Set Maint. Window CLOSE ----------------------------- Window Name : MONDAY_WINDOW Enabled? : TRUE Active? : FALSE ----------------------------- PL/SQL ???????? SQL> drop table employee purge ; ????? ???? ????? spool ilm_usecase_1_cleanup.lst @ilm_demo_cleanup ; spool off

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  • How to query range of data in DB2 with highest performance?

    - by Fuangwith S.
    Usually, I need to retrieve data from a table in some range; for example, a separate page for each search result. In MySQL I use LIMIT keyword but in DB2 I don't know. Now I use this query for retrieve range of data. SELECT * FROM( SELECT SMALLINT(RANK() OVER(ORDER BY NAME DESC)) AS RUNNING_NO , DATA_KEY_VALUE , SHOW_PRIORITY FROM EMPLOYEE WHERE NAME LIKE 'DEL%' ORDER BY NAME DESC FETCH FIRST 20 ROWS ONLY ) AS TMP ORDER BY TMP.RUNNING_NO ASC FETCH FIRST 10 ROWS ONLY but I know it's bad style. So, how to query for highest performance?

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  • Bad performance function in PHP. With large files memory blows up! How can I refactor?

    - by André
    Hi I have a function that strips out lines from files. I'm handling with large files(more than 100Mb). I have the PHP Memory with 256MB but the function that handles with the strip out of lines blows up with a 100MB CSV File. What the function must do is this: Originally I have the CSV like: Copyright (c) 2007 MaxMind LLC. All Rights Reserved. locId,country,region,city,postalCode,latitude,longitude,metroCode,areaCode 1,"O1","","","",0.0000,0.0000,, 2,"AP","","","",35.0000,105.0000,, 3,"EU","","","",47.0000,8.0000,, 4,"AD","","","",42.5000,1.5000,, 5,"AE","","","",24.0000,54.0000,, 6,"AF","","","",33.0000,65.0000,, 7,"AG","","","",17.0500,-61.8000,, 8,"AI","","","",18.2500,-63.1667,, 9,"AL","","","",41.0000,20.0000,, When I pass the CSV file to this function I got: locId,country,region,city,postalCode,latitude,longitude,metroCode,areaCode 1,"O1","","","",0.0000,0.0000,, 2,"AP","","","",35.0000,105.0000,, 3,"EU","","","",47.0000,8.0000,, 4,"AD","","","",42.5000,1.5000,, 5,"AE","","","",24.0000,54.0000,, 6,"AF","","","",33.0000,65.0000,, 7,"AG","","","",17.0500,-61.8000,, 8,"AI","","","",18.2500,-63.1667,, 9,"AL","","","",41.0000,20.0000,, It only strips out the first line, nothing more. The problem is the performance of this function with large files, it blows up the memory. The function is: public function deleteLine($line_no, $csvFileName) { // this function strips a specific line from a file // if a line is stripped, functions returns True else false // // e.g. // deleteLine(-1, xyz.csv); // strip last line // deleteLine(1, xyz.csv); // strip first line // Assigna o nome do ficheiro $filename = $csvFileName; $strip_return=FALSE; $data=file($filename); $pipe=fopen($filename,'w'); $size=count($data); if($line_no==-1) $skip=$size-1; else $skip=$line_no-1; for($line=0;$line<$size;$line++) if($line!=$skip) fputs($pipe,$data[$line]); else $strip_return=TRUE; return $strip_return; } It is possible to refactor this function to not blow up with the 256MB PHP Memory? Give me some clues. Best Regards,

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  • Multi-tenant ASP.NET MVC – Introduction

    - by zowens
    I’ve read a few different blogs that talk about multi-tenancy and how to resolve some of the issues surrounding multi-tenancy. What I’ve come to realize is that these implementations overcomplicate the issues and give only a muddy implementation! I’ve seen some really illogical code out there. I have recently been building a multi-tenancy framework for internal use at eagleenvision.net. Through this process, I’ve realized a few different techniques to make building multi-tenant applications actually quite easy. I will be posting a few different entries over the issue and my personal implementation. In this first post, I will discuss what multi-tenancy means and how my implementation will be structured.   So what’s the problem? Here’s the deal. Multi-tenancy is basically a technique of code-reuse of web application code. A multi-tenant application is an application that runs a single instance for multiple clients. Here the “client” is different URL bindings on IIS using ASP.NET MVC. The problem with different instances of the, essentially, same application is that you have to spin up different instances of ASP.NET. As the number of running instances of ASP.NET grows, so does the memory footprint of IIS. Stack Exchange shifted its architecture to multi-tenancy March. As the blog post explains, multi-tenancy saves cost in terms of memory utilization and physical disc storage. If you use the same code base for many applications, multi-tenancy just makes sense. You’ll reduce the amount of work it takes to synchronize the site implementations and you’ll thank your lucky stars later for choosing to use one application for multiple sites. Multi-tenancy allows the freedom of extensibility while relying on some pre-built code.   You’d think this would be simple. I have actually seen a real lack of reference material on the subject in terms of ASP.NET MVC. This is somewhat surprising given the number of users of ASP.NET MVC. However, I will certainly fill the void ;). Implementing a multi-tenant application takes a little thinking. It’s not straight-forward because the possibilities of implementation are endless. I have yet to see a great implementation of a multi-tenant MVC application. The only one that comes close to what I have in mind is Rob Ashton’s implementation (all the entries are listed on this page). There’s some really nasty code in there… something I’d really like to avoid. He has also written a library (MvcEx) that attempts to aid multi-tenant development. This code is even worse, in my honest opinion. Once I start seeing Reflection.Emit, I have to assume the worst :) In all seriousness, if his implementation makes sense to you, use it! It’s a fine implementation that should be given a look. At least look at the code. I will reference MvcEx going forward as a comparison to my implementation. I will explain why my approach differs from MvcEx and how it is better or worse (hopefully better).   Core Goals of my Multi-Tenant Implementation The first, and foremost, goal is to use Inversion of Control containers to my advantage. As you will see throughout this series, I pass around containers quite frequently and rely on their use heavily. I will be using StructureMap in my implementation. However, you could probably use your favorite IoC tool instead. <RANT> However, please don’t be stupid and abstract your IoC tool. Each IoC is powerful and by abstracting the capabilities, you’re doing yourself a real disservice. Who in the world swaps out IoC tools…? No one!</RANT> (It had to be said.) I will outline some of the goodness of StructureMap as we go along. This is really an invaluable tool in my tool belt and simple to use in my multi-tenant implementation. The second core goal is to represent a tenant as easily as possible. Just as a dependency container will be a first-class citizen, so will a tenant. This allows us to easily extend and use tenants. This will also allow different ways of “plugging in” tenants into your application. In my implementation, there will be a single dependency container for a single tenant. This will enable isolation of the dependencies of the tenant. The third goal is to use composition as a means to delegate “core” functions out to the tenant. More on this later.   Features In MvcExt, “Modules” are a code element of the infrastructure. I have simplified this concept and have named this “Features”. A feature is a simple element of an application. Controllers can be specified to have a feature and actions can have “sub features”. Each tenant can select features it needs and the other features will be hidden to the tenant’s users. My implementation doesn’t require something to be a feature. A controller can be common to all tenants. For example, (as you will see) I have a “Content” controller that will return the CSS, Javascript and Images for a tenant. This is common logic to all tenants and shouldn’t be hidden or considered a “feature”; Content is a core component.   Up next My next post will be all about the code. I will reveal some of the foundation to the way I do multi-tenancy. I will have posts dedicated to Foundation, Controllers, Views, Caching, Content and how to setup the tenants. Each post will be in-depth about the issues and implementation details, while adhering to my core goals outlined in this post. As always, comment with questions of DM me on twitter or send me an email.

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  • SQL SERVER – Generate Database Script for SQL Azure

    - by pinaldave
    When talking about SQL Azure the common complain I hear is that the script generated from stand-along SQL Server database is not compatible with SQL Azure. This was true for some time for sure but not any more. If you have SQL Server 2008 R2 installed you can follow the guideline below to generate script which is compatible with SQL Azure. As above images are very clear I will not write more about them. SQL Azure does not support filegroups. Let us generate script for any table created on PRIMARY filegroup for standalong SQL Server and compare it with the script generated for SQL Azure. You can clearly see that there is no filegroup in the code generated for SQL Azure. Give it a try and please your comment here about what do you think about the same. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Add-On, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: SQL Azure

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  • Do not use “using” in WCF Client

    - by oazabir
    You know that any IDisposable object must be disposed using using. So, you have been using using to wrap WCF service’s ChannelFactory and Clients like this: using(var client = new SomeClient()) {. ..} Or, if you are doing it the hard and slow way (without really knowing why), then: using(var factory = new ChannelFactory<ISomeService>()) {var channel= factory.CreateChannel();...} That’s what we have all learnt in school right? We have learnt it wrong! When there’s a network related error or the connection is broken, or the call is timed out before Dispose is called by the using keyword, then it results in the following exception when the using keyword tries to dispose the channel: failed: System.ServiceModel.CommunicationObjectFaultedException : The communication object, System.ServiceModel.Channels.ServiceChannel, cannot be used for communication because it is in the Faulted state. Server stack trace: at System.ServiceModel.Channels.CommunicationObject.Close(TimeSpan timeout) Exception rethrown at [0]: at System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg) at System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type) at System.ServiceModel.ICommunicationObject.Close(TimeSpan timeout) at System.ServiceModel.ClientBase`1.System.ServiceModel.ICommunicationObject.Close(TimeSpan timeout) at System.ServiceModel.ClientBase`1.Close() at System.ServiceModel.ClientBase`1.System.IDisposable.Dispose() There are various reasons for which the underlying connection can be at broken state before the using block is completed and the .Dispose() is called. Common problems like network connection dropping, IIS doing an app pool recycle at that moment, some proxy sitting between you and the service dropping the connection for various reasons and so on. The point is, it might seem like a corner case, but it’s a likely corner case. If you are building a highly available client, you need to treat this properly before you go-live. So, do NOT use using on WCF Channel/Client/ChannelFactory. Instead you need to use an alternative. Here’s what you can do: First create an extension method. public static class WcfExtensions{ public static void Using<T>(this T client, Action<T> work) where T : ICommunicationObject { try { work(client); client.Close(); } catch (CommunicationException e) { client.Abort(); } catch (TimeoutException e) { client.Abort(); } catch (Exception e) { client.Abort(); throw; } }} Then use this instead of the using keyword: new SomeClient().Using(channel => { channel.Login(username, password);}); Or if you are using ChannelFactory then: new ChannelFactory<ISomeService>().Using(channel => { channel.Login(username, password);}); Enjoy!

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  • SQL SERVER – A Quick Note on DB_ID() and DB_NAME() – Get Current Database ID – Get Current Database Name

    - by pinaldave
    Quite often a simple things makes experienced DBA to look for simple thing. Here are few things which I used to get confused couple of years ago. Now I know it well and have no issue but recently I see one of the DBA getting confused when looking at the DBID from one of the DMV and not able to related that directly to Database Name. -- Get Current DatabaseID SELECT DB_ID() DatabaseID; -- Get Current DatabaseName SELECT DB_NAME() DatabaseName; -- Get DatabaseName from DatabaseID SELECT DB_NAME(4) DatabaseID; -- Get DatabaseID from DatabaseName SELECT DB_ID('tempdb') DatabaseName; -- Get all DatabaseName and DBID SELECT name,database_id FROM sys.databases; Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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