How to Find Slow SQL: Databases for Developers: Performance #9

In order to tune SQL, you need to know what the slow statement is. But often you're just told that "the database" is slow!

To find the slow components, you need a breakdown of how long each piece of code takes to execute. You can do this in Oracle Database using:

- A SQL trace
- The PL/SQL hierarchical profiler

This video shows you how to do these with Oracle SQL Developer.

The script to spool the trace file is:

-----
set serveroutput off
set pagesize 0
set echo off
set feedback off
set trimspool on
set heading off
set tab off
set long 1000000
spool c:\temp\student_trace.trc

select payload
from v$diag_trace_file_contents
where trace_filename = (
select substr (
value,
instr ( value, '/', -1 ) + 1
) filename
from v$diag_info
where name = 'Default Trace File'
)
order by line_number;

spool off

-----

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The Magic of SQL with Chris Saxon

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Видео How to Find Slow SQL: Databases for Developers: Performance #9 канала The Magic of SQL