Top "Sql-execution-plan" questions

A execution, or query plan, is the breakdown of steps the database engine uses to get a result.

SQL explain plan: what is Materialize?

I asked PostgreSQL to explain my query. Part of the explanation was: table_name --> Materialize What does materialize …

sql postgresql sql-execution-plan
difference between explain plan and execution plan

Can anyone explain me what is the difference between execution plan and explain plan. When I execute set autotrace traceonly; …

oracle sql-execution-plan
Difference between table access by index rowid BATCHED and table access by index rowid

I'm using EXPLAIN PLAN in oracle database on a simple SELECT statement just to find out how it works. In …

oracle sql-execution-plan
Keep PostgreSQL from sometimes choosing a bad query plan

I have a strange problem with PostgreSQL performance for a query, using PostgreSQL 8.4.9. This query is selecting a set of …

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What is the difference between Seq Scan and Bitmap heap scan in postgres?

In output of explain command I found two terms 'Seq Scan' and 'Bitmap heap Scan'. Can somebody tell me what …

optimization postgresql query-optimization sql-execution-plan
Getting rid of Table Spool in SQL Server Execution plan

I have a query that creates several temporary tables and then inserts data into them. From what I understand this …

sql sql-server sql-execution-plan
query optimizer operator choice - nested loops vs hash match (or merge)

One of my stored procedures was taking too long execute. Taking a look at query execution plan I was able …

sql-server-2008 tsql sql-execution-plan
Query cost relative to batch is 100%

I'm not sure sure how to interpret this, but all the queries I run in sql server 2005 have a "query …

sql-server sql-server-2005 sql-execution-plan indexing
Execution plan over query with temp tables

I've a stored procedure that does something like this: SELECT Id INTO #temp FROM table WHERE ... DELETE FROM #temp INNER …

sql-server sql-server-2008-r2 sql-execution-plan
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_…

sql mysql performance query-optimization sql-execution-plan