sql-execution-plan

Just requesting some clarification on the difference between the 2. From what I understand, EXPLAIN PLAN gives you the theoretical execution plan while DBMS_XPLAN.DISPLAY_CURSOR gives you the actual execution plan with execution statistics for the statement. EXPLAIN PLAN stores this data in a PLAN_TABLE while DBMS_XPLAN uses the V$SQL_PLAN, V$SQL_PLAN_STATISTICS and V$SQL_PLAN_STATISTICS_ALL views for its information. However, for DISPLAY_CURSOR to collect the actual runtime statistics for that statment, one needs to set the /*+ gather_plan_statistics */ hint. Otherwise, only V$SQL_PLAN is

I have a stored proc that searches for products (250,000 rows) using a full text index. The stored proc takes a parameter that is the full text search condition. This parameter can be null, so I added a null check and the query suddenly started running orders of magnitude slower. -- This is normally a parameter of my stored proc DECLARE @Filter VARCHAR(100) SET @Filter = 'FORMSOF(INFLECTIONAL, robe)' -- #1 - Runs < 1 sec SELECT TOP 100 ID FROM dbo.Products WHERE CONTAINS(Name, @Filter) -- #2 - Runs in 18 secs SELECT TOP 100 ID FROM dbo.Products WHERE @Filter IS NULL OR CONTAINS(Name, @Filter)

If I run this command in SSMS: set showplan_xml on GO exec some_procedure 'arg1', 'arg2','arg3' GO set showplan_xml off GO I get XML output of the full call stack involved in the query execution, as well as any suggested indexes etc. How might one read this from C#? (One use case might be to periodically enable this and log these results in a production environment to keep an eye on index suggestions.) This is, for the most part, two separate (though related) questions. Is it possible to capture or somehow get the Missing Index information? If you want only the Suggested Indexes (and don't

I would expect these two SELECT s to have the same execution plan and performance. Since there is a leading wildcard on the LIKE , I expect an index scan. When I run this and look at the plans, the first SELECT behaves as expected (with a scan). But the second SELECT plan shows an index seek, and runs 20 times faster. Code: -- Uses index scan, as expected: SELECT 1 FROM AccountAction WHERE AccountNumber LIKE '%441025586401' -- Uses index seek somehow, and runs much faster: declare @empty VARCHAR(30) = '' SELECT 1 FROM AccountAction WHERE AccountNumber LIKE '%441025586401' + @empty Question:

I have a query that fails to execute with "Could not allocate a new page for database 'TEMPDB' because of insufficient disk space in filegroup 'DEFAULT'". On the way of trouble shooting I am examining the execution plan. There are two costly steps labeled "Clustered Index Scan (Clustered)". I have a hard time find out what this means? I would appreciate any explanations to "Clustered Index Scan (Clustered)" or suggestions on where to find the related document? Neeraj Prasad Sharma I would appreciate any explanations to "Clustered Index Scan (Clustered)" I will try to put in the easiest manner,