You can define a custom position for the cursor hotspot by adding x & y coordinates for where the hotspot should be in the provided custom image. You can also provide a fallback to one of the non-custom cursors. cur fallback if you want to use an svg cursor. cur files are supported across the board, so it can be a good idea to provide a. Note that not all browsers support svg files for cursors, and. 142 ms vs 182 ms (100 runs).Īnother tip that has no performance impact, but helps the developers – I use always a WHILE 1 = 1 loop, fetch the records in the first statment and BREAK when no more records could be fetched.You can define custom cursors. On smaller (more realistic) recordsets as a simple SELECT 1 FROM sys.all_objects (~8k rows, which is still a lot) FORWARD_ONLY STATIC wins with avg. Your test query returns in my database ~2 mio records.
I repeated your test on my local PC and can validate, that FAST_FORWARD is slightly faster than an FORWARD_ONLY STATIC on BIG recordsets (avg.
BEGIN TRAN DECLARE INT DECLARE TMP_Cursor CURSOR DYNAMIC -DECLARE TMP_Cursor CURSOR FAST_FORWARD -DECLARE TMP_Cursor CURSOR STATIC READ_ONLY FORWARD_ONLY FOR SELECT IDįROM Funcionarios WITH ( index =ix_Salario ) WHERE Salario < 3000 OPEN TMP_CursorįETCH NEXT FROM TMP_Cursor INTO WHILE = 0 BEGIN SELECT * FROM Funcionarios WITH ( index =ix_Salario ) UPDATE Funcionarios SET Salario = Salario * 1.1 WHERE ID = FETCH NEXT FROM TMP_Cursor INTO END CLOSE TMP_Cursor Salario Numeric ( 18, 2 ) ) GO INSERT INTO Funcionarios (ContactName, Salario ) VALUES ( 'Fabiano', 1900 ) INSERT INTO Funcionarios (ContactName, Salario ) VALUES ( 'Luciano', 2050 ) INSERT INTO Funcionarios (ContactName, Salario ) VALUES ( 'Gilberto', 2070 ) INSERT INTO Funcionarios (ContactName, Salario ) VALUES ( 'Ivan', 2090 ) GO CREATE NONCLUSTERED INDEX ix_Salario ON Funcionarios (Salario ) GO - Halloween problem, will update all rows until then reach 3000 !!! UPDATE Funcionarios SET Salario = Salario * 1.1 FROM Funcionarios WITH ( index =ix_Salario ) WHERE Salario < 3000 GO - Simulate here with all different CURSOR declarations - DYNAMIC update the rows until all of then reach 3000 - FAST_FORWARD update the rows until all of then reach 3000 - STATIC update the rows only one time. GO CREATE TABLE Funcionarios (ID Int IDENTITY ( 1, 1 ) PRIMARY KEY , IF OBJECT_ID ( 'Funcionarios' ) IS NOT NULL DROP TABLE Funcionarios In my experience it has proved to be the fastest option in general overall in real life use cases and can have the least amount of CPU usage as well. As such in a heavily used environment it can actually be much faster than any of the other options.
Where as a STATIC cursor only hits the table once and all further actions are against the copy in tempdb which has no need for dealing with concurrency options. This can be from both sides meaning that it can cause blocking and be blocked. Even LOCAL FAST_FORWARD cursors go back to the original source with new fetches and do take locks and latches which can interfere with a highly concurrent operation. One thing I want to point out is that even though Static may not have the smallest footprint out of the cursors and might be slightly slower under these conditions it can be dramatically faster in a heavy use / high concurrency one. I am just now seeing this post so forgive me for the late reply.
This was not the case again we see a roughly 5X hit on tempdb usage with the default cursor and the one with only LOCAL specified:įor years I have been stressing that the following option should always be specified for your cursors: Since the definition of a static cursor means that it copies the entire result to tempdb, and it is actually expressed in sys.dm_exec_cursors as SNAPSHOT, I expected the hit on tempdb pages to be higher with all static variants of the cursor. The best combination here was LOCAL FAST_FORWARD: So I simply restarted before each cold cache test, measuring the performance counter Total Server Memory (KB) before and after each test. I also wanted to measure the additional memory that SQL Server would request when fulfilling each cursor type. Quite arguably the most important and common measure is, "how long did it take?" Well, it took almost five times as long to run a cursor with the default options (or with only LOCAL specified), compared to specifying either STATIC or FAST_FORWARD:
OPEN c FETCH c INTO WHILE ( = 0 ) BEGIN SET += 1 - meaningless operation FETCH c INTO END CLOSE c DEALLOCATE c Results objects AS c1ĬROSS JOIN ( SELECT TOP 500 name FROM sys. DECLARE INT = 1 DECLARE c CURSOR - LOCAL - LOCAL STATIC - LOCAL FAST_FORWARD - LOCAL STATIC READ_ONLY FORWARD_ONLY FOR SELECT c1.