All Questions
Tagged with sql sql-execution-plan
535
questions
381
votes
13
answers
513k
views
How do I obtain a Query Execution Plan in SQL Server?
In Microsoft SQL Server how can I get a query execution plan for a query / stored procedure?
- 86.1k
97
votes
6
answers
104k
views
SQL Server Plans : difference between Index Scan / Index Seek
In a SQL Server Execution plan what is the difference between an Index Scan and an Index Seek
I'm on SQL Server 2005.
- 4,731
93
votes
11
answers
65k
views
How do you interpret a query's explain plan?
When attempting to understand how a SQL statement is executing, it is sometimes recommended to look at the explain plan. What is the process one should go through in interpreting (making sense) of an ...
user290
62
votes
3
answers
222k
views
How do I view the Explain Plan in Oracle Sql developer?
I have few SQL queries which has very low query running performance and I want to check the query execution plan for this query. I am trying to execute the below query but its not showing any query ...
- 3,730
62
votes
5
answers
43k
views
SQL explain plan: what is Materialize?
I asked PostgreSQL to explain my query. Part of the explanation was:
table_name --> Materialize
What does materialize do? I'm joining two tables, not views or anything like that.
- 227k
55
votes
6
answers
139k
views
Measuring Query Performance : "Execution Plan Query Cost" vs "Time Taken"
I'm trying to determine the relative performance of two different queries and have two ways of measuring this available to me:
1. Run both and time each query
2. Run both and get "Query Cost" from the ...
- 85.8k
52
votes
7
answers
25k
views
Meaning of "Select tables optimized away" in MySQL Explain plan
What is the meaning of Select tables optimized away in MySQL Explain plan?
explain select count(comment_count) from wp_posts;
+----+-------------+---------------------------+---------------------...
- 17.5k
48
votes
5
answers
62k
views
What "Clustered Index Scan (Clustered)" means on SQL Server execution plan?
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 ...
- 3,794
41
votes
9
answers
92k
views
How to improve performance on a clustered index seek
I'm trying to improve the performance on a query that is running very slowly. After going through the Actual Execution Plan; I found that a Clustered Index Seek was taking up 82%. Is there any way for ...
- 84.3k
31
votes
1
answer
46k
views
How to Clear down Query Execution Statistics in SQL Server 2005/2008
Based on getting Query Execution Statistics using this extremely useful piece of SQL obtained from this post Most Executed Stored Procedure - Stack Overflow:
SELECT TOP 100
qt.TEXT AS 'SP Name',
...
- 1,150
29
votes
3
answers
27k
views
How can I analyse a Sqlite query execution?
I have a Sqlite database which I want to check the indexes are correct. MS SQL Analyser is great at breaking down the query execution and utilised indexes.
Is there a similar tool for Sqlite?
- 12.2k
26
votes
9
answers
13k
views
Performance of SQL "EXISTS" usage variants
Is there any difference in the performance of the following three SQL statements?
SELECT * FROM tableA WHERE EXISTS (SELECT * FROM tableB WHERE tableA.x = tableB.y)
SELECT * FROM tableA WHERE EXISTS ...
- 5,676
24
votes
4
answers
3k
views
Missing STOPKEY per partition in Oracle plan for paging by local index
There is next partitioned table:
CREATE TABLE "ERMB_LOG_TEST_BF"."OUT_SMS"(
"TRX_ID" NUMBER(19,0) NOT NULL ENABLE,
"CREATE_TS" TIMESTAMP (3) DEFAULT systimestamp NOT NULL ENABLE,
/* other ...
- 356
22
votes
8
answers
11k
views
Will my index be used if all columns are not used?
I have an index on columns A, B, C, D of table T
I have a query that pulls from T with A, B, C in the WHERE clause.
Will the index be used or will a separate index be needed that only includes A, B, ...
anon
20
votes
3
answers
35k
views
How do I know if any index is used in a query | PostgreSQL 11?
I am little bit confused and need some advice. I use PostgreSQL 11 database. I have such pretty simple sql statement:
SELECT DISTINCT "CITY", "AREA", "REGION"
FROM youtube
WHERE
"CITY" IS NOT ...
- 5,074