Quantcast
Viewing all articles
Browse latest Browse all 426

How to get Oracle execution plans with Starts, E-Rows, A-Rows and A-Time columns

This can probably be found elsewhere as well, but here’s a short wrap-up how to get the most out of your execution plans, quickly

1. Be sure the actual rows and time statistics are collected.

You can do this with

-- login as user sys
alter system set statistics_level = all;

2. Execute your bad SQL.

I can’t give you an example, because I don’t write bad SQL.

3. Image may be NSFW.
Clik here to view.
;-)

4. Find your sql_id with this statement

-- these are the most important columns
select last_active_time, sql_id, child_number, sql_text
from v$sql
-- filter for your statement
where upper(sql_fulltext) like
  '%[put some text from your SQL statement here]%'
-- this orders by the most recent activity
order by last_active_time desc;

5. Get the cursor and plan for that statement

select rownum, t.* from table(dbms_xplan.display_cursor(
  -- Put the previously retrieved sql_id here
  sql_id => '6dt9vvx9gmd1x',
  -- The cursor child number, in case there are
  -- several plans per cursor
  cursor_child_no => 0,
  -- Some formatting instructions to get Starts,
  -- E-Rows, A-Rows and A-Time
  FORMAT => 'ALLSTATS LAST')) t;

6. Purge the cursors, if needed:

select address || ',' || hash_value from v$sqlarea
where sql_id = '6dt9vvx9gmd1x';

begin
  sys.dbms_shared_pool.purge(
    '00000000F3471988,2224337167','C',1);
end;

7. Delete all execution plans

-- login as user sys
alter system flush shared_pool;

8. Delete buffer cache (IO cache)

-- login as user sys
alter system flush buffer_cache;

Filed under: sql Tagged: actual rows, actual time, buffer cache, estimated rows, execution plans, Oracle, shared pool, sql Image may be NSFW.
Clik here to view.
Image may be NSFW.
Clik here to view.
Image may be NSFW.
Clik here to view.
Image may be NSFW.
Clik here to view.
Image may be NSFW.
Clik here to view.
Image may be NSFW.
Clik here to view.
Image may be NSFW.
Clik here to view.
Image may be NSFW.
Clik here to view.

Viewing all articles
Browse latest Browse all 426

Trending Articles