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From:Brandon Phelps Date:September 8 2011 6:50pm
Subject:Re: Query Optimization
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Andy,

The queries take minutes to run.  MySQL is 5.1.54 and it's running on Ubuntu server 11.04.
 Unfortunately the machine only has 2GB of RAM but no other major daemons are running on
the machine.  We are running RAID 1 (mirroring) with 1TB drives.  The tables in question
here are all MyISAM.  When running with the LIMIT 10 my EXPLAIN is:

+----+-------------+-------+--------+---------------------+---------------------+---------+--------------------+----------+-----------------------------+
| id | select_type | table | type   | possible_keys       | key                 | key_len
| ref                | rows     | Extra                       |
+----+-------------+-------+--------+---------------------+---------------------+---------+--------------------+----------+-----------------------------+
|  1 | SIMPLE      | sc    | range  | ndx_open_close_rcvd | ndx_open_close_rcvd | 8      
| NULL               | 32393316 | Using where; Using filesort |
|  1 | SIMPLE      | spm   | eq_ref | PRIMARY             | PRIMARY             | 2      
| syslog.sc.src_port |        1 |                             |
|  1 | SIMPLE      | dpm   | eq_ref | PRIMARY             | PRIMARY             | 2      
| syslog.sc.dst_port |        1 |                             |
+----+-------------+-------+--------+---------------------+---------------------+---------+--------------------+----------+-----------------------------+

When I remove the LIMIT 10 I get:

----+-------------+-------+--------+---------------------+---------+---------+--------------------+----------+-----------------------------+
| id | select_type | table | type   | possible_keys       | key     | key_len | ref       
        | rows     | Extra                       |
+----+-------------+-------+--------+---------------------+---------+---------+--------------------+----------+-----------------------------+
|  1 | SIMPLE      | sc    | ALL    | ndx_open_close_rcvd | NULL    | NULL    | NULL      
        | 32393330 | Using where; Using filesort |
|  1 | SIMPLE      | spm   | eq_ref | PRIMARY             | PRIMARY | 2       |
syslog.sc.src_port |        1 |                             |
|  1 | SIMPLE      | dpm   | eq_ref | PRIMARY             | PRIMARY | 2       |
syslog.sc.dst_port |        1 |                             |
+----+-------------+-------+--------+---------------------+---------+---------+--------------------+----------+-----------------------------+

Thanks for all your help thus far.

On 09/08/2011 02:38 PM, Andrew Moore wrote:
> I don't think I saw any query timings in the emails (maybe I missed them).
>
> What version of MySQL are you currently using?
> What does the explain look like when your remove the limit 10?
> Is your server tuned for MyISAM or InnoDB?
> What kind of disk setup is in use?
> How much memory is in your machine?
>
>
> On Thu, Sep 8, 2011 at 7:27 PM, Brandon Phelps<bphelps@stripped>  wrote:
>
>> Thanks for the reply Andy.  Unfortunately the users will be selecting
>> varying date ranges and new data is constantly coming in, so I am not sure
>> how I could archive/cache the necessary data that would be any more
>> efficient than simply using the database directly.
>>
>>
>>
>> On 09/08/2011 02:16 PM, Andrew Moore wrote:
>>
>>> Thinking outside the query, is there any archiving that could happen to
>>> make
>>> your large tables kinder in the range scan?
>>>
>>> Andy
>>>
>>> On Thu, Sep 8, 2011 at 7:03 PM, Brandon Phelps<bphelps@stripped>  
> wrote:
>>>
>>>   On 09/01/2011 01:32 PM, Brandon Phelps wrote:
>>>>
>>>>   On 09/01/2011 12:47 PM, Shawn Green (MySQL) wrote:
>>>>>
>>>>>   On 9/1/2011 09:42, Brandon Phelps wrote:
>>>>>>
>>>>>>   On 09/01/2011 04:59 AM, Jochem van Dieten wrote:
>>>>>>>
>>>>>>>> ...
>>>>>>>>>
>>>>>>>>
>>>>>>>   WHERE
>>>>>>>>> (open_dt>= '2011-08-30 00:00:00' OR close_dt>=
> '2011-08-30
>>>>>>>>>
>>>>>>>> 00:00:00')
>>>>>>>
>>>>>>>> AND (open_dt<= '2011-08-30 12:36:53' OR close_dt<=
> '2011-08-30
>>>>>>>>>
>>>>>>>> 12:36:53')
>>>>>>>
>>>>>>>   In that case your logic here simplifies to:
>>>>>>>> WHERE
>>>>>>>> open_dt>= '2011-08-30 00:00:00'
>>>>>>>> AND
>>>>>>>> close_dt<= '2011-08-30 12:36:53'
>>>>>>>>
>>>>>>>
>>>>>>>   Now add an index over open_dt and close_dt and see what
> happens.
>>>>>>>>
>>>>>>>
>>>>>>>   Jochem
>>>>>>>>
>>>>>>>
>>>>>>> Jochem,
>>>>>>>
>>>>>>> I can't really use your WHERE logic because I also need to
> retrieve
>>>>>>> results where the open_dt time is out of the range specified.
> For
>>>>>>> example, a very large file download might span multiple days
> so given
>>>>>>> your logic if the connection was started 2 days ago and I
> want to pull
>>>>>>> 1
>>>>>>> days worth of connections, I would miss that entry. Basically
> I want
>>>>>>> to
>>>>>>> SELECT all of the records that were opened OR closed during
> the
>>>>>>> specified time period, ie. if any activity happened between
> my start
>>>>>>> and
>>>>>>> end dates, I need to see that record.
>>>>>>>
>>>>>>> Any other ideas?
>>>>>>>
>>>>>>>
>>>>>>>   I believe Jochem was on the right track but he got his
> dates
>>>>>> reversed.
>>>>>>
>>>>>> Let's try a little ASCII art to show the situation. I will setup
> a
>>>>>> query
>>>>>> window with two markers (s) and (e). Events will be marked by
> |----|
>>>>>> markers
>>>>>> showing their durations.
>>>>>>
>>>>>> a) (s) (e)
>>>>>> b) |---|
>>>>>> c) |---|
>>>>>> d) |---|
>>>>>> e) |--------------------|
>>>>>> f) |---|
>>>>>> g) |---|
>>>>>>
>>>>>> To describe these situations:
>>>>>> a) is the window for which you want to query (s) is the starting
> time
>>>>>> and
>>>>>> (e) is the ending time for the date range you are interested in.
>>>>>> b) the event starts and stops before your window exists. It won't
> be
>>>>>> part
>>>>>> of your results.
>>>>>> c) the event starts before the window but ends within the window
> -
>>>>>> include this
>>>>>> d) the event starts and ends within the window - include this
>>>>>> e) the event starts before the window and ends after the window
> -
>>>>>> include
>>>>>> this
>>>>>> f) the event starts inside the window but ends beyond the window
> -
>>>>>> include this.
>>>>>> g) the event starts and ends beyond the window - exclude this.
>>>>>>
>>>>>> In order to get every event in the range of c-f, here is what you
> need
>>>>>> for a WHERE clause
>>>>>>
>>>>>> WHERE start<= (ending time) and end>= (starting time)
>>>>>>
>>>>>> Try that and let us know the results.
>>>>>>
>>>>>>
>>>>> Thanks Jochem and Shawn, however the following two queries result in
> the
>>>>> exact same EXPLAIN output: (I hope the tables don't wrap too early
> for
>>>>> you)
>>>>>
>>>>> Old method:
>>>>> SELECT
>>>>> sc.open_dt,
>>>>> sc.close_dt,
>>>>> sc.protocol,
>>>>> INET_NTOA(sc.src_address) AS src_address,
>>>>> sc.src_port,
>>>>> INET_NTOA(sc.dst_address) AS dst_address,
>>>>> sc.dst_port,
>>>>> sc.sent,
>>>>> sc.rcvd,
>>>>> spm.desc AS src_port_desc,
>>>>> dpm.desc AS dst_port_desc
>>>>> FROM firewall_connections AS sc
>>>>> LEFT JOIN port_mappings AS spm ON spm.port = sc.src_port
>>>>> LEFT JOIN port_mappings AS dpm ON dpm.port = sc.dst_port
>>>>> WHERE
>>>>> (open_dt>= '2011-08-31 09:53:31' OR close_dt>= '2011-08-31
> 09:53:31')
>>>>> AND (open_dt<= '2011-09-01 09:53:31' OR close_dt<= '2011-09-01
>>>>> 09:53:31')
>>>>> ORDER BY rcvd DESC
>>>>> LIMIT 0, 10;
>>>>>
>>>>> New method with BTREE index on open_dt, close_dt (index name is
>>>>> ndx_open_close_dt):
>>>>> SELECT
>>>>> sc.open_dt,
>>>>> sc.close_dt,
>>>>> sc.protocol,
>>>>> INET_NTOA(sc.src_address) AS src_address,
>>>>> sc.src_port,
>>>>> INET_NTOA(sc.dst_address) AS dst_address,
>>>>> sc.dst_port,
>>>>> sc.sent,
>>>>> sc.rcvd,
>>>>> spm.desc AS src_port_desc,
>>>>> dpm.desc AS dst_port_desc
>>>>> FROM firewall_connections AS sc
>>>>> LEFT JOIN port_mappings AS spm ON spm.port = sc.src_port
>>>>> LEFT JOIN port_mappings AS dpm ON dpm.port = sc.dst_port
>>>>> WHERE
>>>>> open_dt<= '2011-09-01 09:53:31' AND close_dt>= '2011-08-31
> 09:53:31'
>>>>> ORDER BY rcvd DESC
>>>>> LIMIT 0, 10;
>>>>>
>>>>> EXPLAIN output for old method:
>>>>> +----+-------------+-------+--****------+---------------------**--**
>>>>> ----+----------+---------+----****----------------+------+----**
>>>>> --**-------+
>>>>> | id | select_type | table | type | possible_keys | key | key_len |
> ref
>>>>> |
>>>>> rows | Extra |
>>>>> +----+-------------+-------+--****------+---------------------**--**
>>>>> ----+----------+---------+----****----------------+------+----**
>>>>> --**-------+
>>>>> | 1 | SIMPLE | sc | index | open_dt,ndx_open_close_dt | ndx_rcvd | 4
> |
>>>>> NULL | 10 | Using where |
>>>>> | 1 | SIMPLE | spm | eq_ref | PRIMARY | PRIMARY | 2 |
> syslog.sc.src_port
>>>>> |
>>>>> 1 | |
>>>>> | 1 | SIMPLE | dpm | eq_ref | PRIMARY | PRIMARY | 2 |
> syslog.sc.dst_port
>>>>> |
>>>>> 1 | |
>>>>> +----+-------------+-------+--****------+---------------------**--**
>>>>> ----+----------+---------+----****----------------+------+----**
>>>>> --**-------+
>>>>>
>>>>> EXPLAIN output for new method with new index:
>>>>> +----+-------------+-------+--****------+---------------------**--**
>>>>> ----+----------+---------+----****----------------+------+----**
>>>>> --**-------+
>>>>> | id | select_type | table | type | possible_keys | key | key_len |
> ref
>>>>> |
>>>>> rows | Extra |
>>>>> +----+-------------+-------+--****------+---------------------**--**
>>>>> ----+----------+---------+----****----------------+------+----**
>>>>> --**-------+
>>>>> | 1 | SIMPLE | sc | index | open_dt,ndx_open_close_dt | ndx_rcvd | 4
> |
>>>>> NULL | 10 | Using where |
>>>>> | 1 | SIMPLE | spm | eq_ref | PRIMARY | PRIMARY | 2 |
> syslog.sc.src_port
>>>>> |
>>>>> 1 | |
>>>>> | 1 | SIMPLE | dpm | eq_ref | PRIMARY | PRIMARY | 2 |
> syslog.sc.dst_port
>>>>> |
>>>>> 1 | |
>>>>> +----+-------------+-------+--****------+---------------------**--**
>>>>> ----+----------+---------+----****----------------+------+----**
>>>>> --**-------+
>>>>>
>>>>> SHOW INDEX:
>>>>> +----------------------+------****------+-------------------+-**--**
>>>>> -----------+-------------+----****-------+-------------+------**--**
>>>>> --+--------+------+-----------****-+---------+
>>>>> | Table | Non_unique | Key_name | Seq_in_index | Column_name |
> Collation
>>>>> |
>>>>> Cardinality | Sub_part | Packed | Null | Index_type | Comment |
>>>>> +----------------------+------****------+-------------------+-**--**
>>>>> -----------+-------------+----****-------+-------------+------**--**
>>>>> --+--------+------+-----------****-+---------+
>>>>> | firewall_connections | 1 | ndx_open_close_dt | 1 | open_dt | A |
>>>>> 1342691
>>>>> | NULL | NULL | | BTREE | |
>>>>> | firewall_connections | 1 | ndx_open_close_dt | 2 | close_dt | A |
>>>>> 6377783 | NULL | NULL | | BTREE | |
>>>>> +----------------------+------****------+-------------------+-**--**
>>>>> -----------+-------------+----****-------+-------------+------**--**
>>>>> --+--------+------+-----------****-+---------+
>>>>>
>>>>>
>>>>> Although right now the queries do seem to be executing much faster,
>>>>> although I'm not quite sure why. And I'm not sure why the new
>>>>> ndx_open_close_dt isn't being used either.
>>>>>
>>>>> -Brandon
>>>>>
>>>>>
>>>>>   I am still having a big issue with my query as seen above.  The
> table
>>>> is up
>>>> to around 32 million records at the moment and either of the two SELECT
>>>> queries above take a very long time to run.  Is there anything at all I
>>>> can
>>>> do to speed things up?  It seems that changing the format of the WHERE
>>>> clause did not help at all, as the EXPLAIN output is exactly the same
> for
>>>> both version.  I also tried adding an index on (open_dt, close_dt, rcvd)
>>>> but
>>>> that index does not get used.
>>>>
>>>> Any other ideas?
>>>>
>>>> Thanks in advance,
>>>>
>>>>
>>>> Brandon
>>>>
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>>>>>
>>>>
>>>>
>>>>
>>>
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>
Thread
Query OptimizationBrandon Phelps30 Aug
  • Re: Query OptimizationMichael Dykman30 Aug
  • Re: Query OptimizationJochem van Dieten1 Sep
    • Re: Query OptimizationBrandon Phelps1 Sep
      • Re: Query OptimizationMySQL)1 Sep
        • Re: Query OptimizationBrandon Phelps1 Sep
          • Re: Query OptimizationBrandon Phelps8 Sep
            • Re: Query OptimizationAndrew Moore8 Sep
              • Re: Query OptimizationBrandon Phelps8 Sep
                • Re: Query OptimizationAndrew Moore8 Sep
                  • Re: Query OptimizationBrandon Phelps8 Sep
                    • Re: Query OptimizationDerek Downey8 Sep
                      • Re: Query OptimizationBrandon Phelps8 Sep
                        • Re: Query OptimizationMihail Manolov8 Sep
                          • Re: Query OptimizationBrandon Phelps8 Sep
                            • Re: Query OptimizationMihail Manolov8 Sep
                              • Re: Query OptimizationBrandon Phelps8 Sep
                • Re: Query OptimizationMihail Manolov8 Sep
                  • Re: Query OptimizationBrandon Phelps8 Sep
                    • Re: Query OptimizationAndrew Moore8 Sep
                      • Re: Query OptimizationBrandon Phelps8 Sep