How do you check the performance of a query in Toad?

Notice the Query Viewer tab along the bottom third of Toad for Oracle. This display shows the SQL you have been executing and its runtime. You click on one and it will also show you the SQL.

What is Oracle optimization?

Query optimization is the overall process of choosing the most efficient means of executing a SQL statement. SQL is a nonprocedural language, so the optimizer is free to merge, reorganize, and process in any order. The database optimizes each SQL statement based on statistics collected about the accessed data.

How do you optimize a join in Oracle?

Nested Loops Join

1. The optimizer chooses one of the tables as the outer table, or the driving table.
2. For each row in the outer table, Oracle finds all rows in the inner table that satisfy the join condition.
3. Oracle combines the data in each pair of rows that satisfy the join condition and returns the resulting rows.

What is Oracle Optimizer cost?

The Oracle cost-based optimizer (CBO) displays the cost number for a query, or an estimate based on statistics and calculations. The cost number is the estimated number of physical I/O operations Oracle thinks it will have to find the requested data, based solely on statistics.

How do you speed up a toad?

Therefore, toad begins to query the data dictionary for the list of objects. It should be quicker second time around when you query that object. You can also manually refresh by using the picklist-dropdown. There should be a refresh button in the top left.

How do you optimize a query in PL SQL?

Avoiding CPU Overhead in PL/SQL Code

1. Make SQL Statements as Efficient as Possible.
2. Make Function Calls as Efficient as Possible.
3. Make Loops as Efficient as Possible.
4. Don’t Duplicate Built-in String Functions.
5. Reorder Conditional Tests to Put the Least Expensive First.
6. Minimize Datatype Conversions.

What should be known to the query optimizer in order to optimize a query?

Join ordering Most query optimizers determine join order via a dynamic programming algorithm pioneered by IBM’s System R database project. This algorithm works in two stages: First, all ways to access each relation in the query are computed. Every relation in the query can be accessed via a sequential scan.