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Detailed explanation of MySQL using profile to analyze slow SQL code examples

黄舟

Mar 16, 2017 pm 01:36 PM

Recently, a sql statement query using subquery is very slow and seriously affects the performance, so it needs to be optimized. The following article mainly introduces to you about MySQLUse profile to analyze the relevant information of slow sql. The article introduces it in great detail. Friends who need it can refer to it. Let’s take a look together.

Use profile to analyze slow sql

##The main purpose of mysql's sql performance analyzer is to display the usage of various resources during the entire process of sql execution. The analyzer can. It better shows the performance problems of bad SQL. Recently, I encountered a SQL statement with a relatively slow query. It took about 0.8 seconds. This took a long time and seriously affected the performance, so it needed to be optimized. Querying a single table or sub-query records

is very fast. Let’s take a look at the detailed introduction

##Open profile

mysql> show profiles; -- 查看是否开启
Empty set, 1 warning (0.00 sec)
mysql> set profiling=1; -- 开启profile
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> show profiles;
Empty set, 1 warning (0.00 sec)
mysql>

Execute queries to facilitate profile tracking records

mysql> SELECT SQL_NO_CACHE
 ->     t1.amount,
 ->     t1.count,
 ->     t1.date ,
 ->     (SELECT (CONCAT(t2.APPROVE_ID,'|' ,t2.PATH)) AS RECEIPT FROM TB_BIS_MERCHANT_SETTLEMENT t2 
 WHERE t2.`MERCHANT_ID` = t1.`MERCHANT_ID` AND t2.`DATE`=t1.DATE AND t2.APPROVE_STATUS=5) AS receipts
 ->    FROM
 ->     TB_BIS_MERCHANT_TURNOVER t1
 ->    WHERE t1.MERCHANT_ID='64884DE062BC11E682B00017FA000202'
 ->         ORDER BY t1.date DESC
 -> 
 -> LIMIT 0,100;
+-----------+-------+----------+------------------------------------------------------------------------------------------------------------+
| amount | count | date  | receipts                         |
+-----------+-------+----------+------------------------------------------------------------------------------------------------------------+
| 15800.00 |  1 | 20170105 | 0DDFD555F93B45BEB0905B1E6DE89D29|http://testxxx.cn/group1/M00/00/49/CvkBIlhu-yqABqmAABYR7dHOmno819.jpg |
| 1245.00 |  1 | 20170104 | 0DDFD555F93B45BEB0905B1E6DE89D29|http://testxxx.cn/group1/M00/00/4F/CvkBIVhtpSeAI_YHAADNjq7TPq8244.jpg |
| 14766.00 |  4 | 20170103 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/45/CvkBIlhrrf6AQ5uIAAEobJv68FU398.jpg |
| 32449.00 |  2 | 20170102 | 0DDFD555F93B45BEB0905B1E6DE89D29|http://testxxx.cn/group1/M00/00/4C/CvkBIVhrDguAfaMIABjKB9uvu04477.jpg |
| 37246.00 |  5 | 20170101 | 0DDFD555F93B45BEB0905B1E6DE89D29|http://testxxx.cn/group1/M00/00/4A/CvkBIVhpCnGASEyLAAEu6l9SI0o812.jpg |
| 105094.00 |  2 | 20161231 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/49/CvkBIVhnwp-ALIvWAAEAaGPayjg732.jpg |
| 88032.00 |  3 | 20161230 | 98FDB31FE4B04C21BC7EBE8A22981DA0|http://testxxx.cn/group1/M00/00/47/CvkBIVhmaqSAHcEZAAFAyS8Zx8Q067.jpg |
| 3845.00 |  1 | 20161229 | 98FDB31FE4B04C21BC7EBE8A22981DA0|http://testxxx.cn/group1/M00/00/3F/CvkBIlhl206AaS-FAAFMhvX8PYY578.jpg |
| 2118.00 |  4 | 20161228 | 2154FDCDA51A4257811F1EA886AACD14|http://testxxx.cn/group1/M00/00/3D/CvkBIlhjxhyAMOfhAAD8wUzTUUY855.jpg |
| 2980.00 |  1 | 20161227 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/3B/CvkBIlhicfCAFmwgAAE9ULPqEJ4030.jpg |
| 1080.00 |  1 | 20161226 | 667E240C44B4469892C261CE9243A8C3|http://testxxx.cn/group1/M00/00/42/CvkBIVhhy6iAMm8tAAFHOT5zBiM875.jpg |
| 2980.00 |  1 | 20161225 | 0DDFD555F93B45BEB0905B1E6DE89D29|http://testxxx.cn/group1/M00/00/40/CvkBIVhfzCWAdw2LAAFpDXmwio4327.jpg |
| 10201.00 |  1 | 20161224 | 98FDB31FE4B04C21BC7EBE8A22981DA0|http://testxxx.cn/group1/M00/00/38/CvkBIlhfJfKAIoBiAADqgbF1pBo054.jpg |
| 3003.00 |  4 | 20161223 | 98FDB31FE4B04C21BC7EBE8A22981DA0|http://testxxx.cn/group1/M00/00/3D/CvkBIVhdMHeAQi8cAAGAOQTgxLo422.jpg |
| 2698.00 |  1 | 20161222 | 98FDB31FE4B04C21BC7EBE8A22981DA0|http://testxxx.cn/group1/M00/00/3C/CvkBIVhb2U2AXWRuAAEc4LIr2nc172.jpg |
| 990.00 |  1 | 20161221 | 98FDB31FE4B04C21BC7EBE8A22981DA0|http://testxxx.cn/group1/M00/00/3B/CvkBIVhbM6aAGMQAAAEQ9ptn0FU333.jpg |
| 1427.00 |  1 | 20161220 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/31/CvkBIlhZNJqAAsvWAAGuJ6g1pyU541.jpg |
| 2465.00 |  1 | 20161219 | 2154FDCDA51A4257811F1EA886AACD14|http://testxxx.cn/group1/M00/00/30/CvkBIlhX4_mAfn-SAAEptH1Fyp8152.jpg |
| 2360.00 |  1 | 20161218 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/2F/CvkBIlhWl_-AclhbAAGLv79hoh8428.jpg |
| 3998.00 |  1 | 20161217 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/35/CvkBIVhVSLGAFct_AAFQRetyWnc285.jpg |
|  0.00 |  0 | 20161216 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/2D/CvkBIlhU8g-AXywcAAGn1gdsQQc959.jpg |
|  0.00 |  0 | 20161215 | 98FDB31FE4B04C21BC7EBE8A22981DA0|http://testxxx.cn/group1/M00/00/2A/CvkBIlhSmryAZXITAG-zN3WQv4c789.jpg |
| 9900.00 |  1 | 20161214 | 98FDB31FE4B04C21BC7EBE8A22981DA0|http://testxxx.cn/group1/M00/00/31/CvkBIVhRTrOALwG6AAE_csC3lvk695.jpg |
| 4320.00 |  1 | 20161213 | 2154FDCDA51A4257811F1EA886AACD14|http://testxxx.cn/group1/M00/00/28/CvkBIlhQrzCAfApEAAFKbHqkH3w634.jpg |
| 8760.00 |  2 | 20161212 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/26/CvkBIlhOqjeAO1BdAAGHdajOU2E697.jpg |
| 213335.00 |  4 | 20161211 | 2154FDCDA51A4257811F1EA886AACD14|http://testxxx.cn/group1/M00/00/2D/CvkBIVhNYQSAfxXgAAHZL9a8Nrs596.jpg |
| 47104.00 |  5 | 20161210 | 98FDB31FE4B04C21BC7EBE8A22981DA0|http://testxxx.cn/group1/M00/00/2C/CvkBIVhMsPSAAnrAAAETxX9fCuw946.jpg |
| 6100.00 |  1 | 20161209 | 98FDB31FE4B04C21BC7EBE8A22981DA0|http://testxxx.cn/group1/M00/00/23/CvkBIlhLfXOAClJVAAFmuoqBI5o264.jpg |
| 13515.00 |  2 | 20161208 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/21/CvkBIlhJZ06AbuaNAAGg7Bz3OsA569.jpg |
| 26769.00 |  4 | 20161207 | 98FDB31FE4B04C21BC7EBE8A22981DA0|http://testxxx.cn/group1/M00/00/20/CvkBIlhIGgeAdNxuAAETxX9fCuw408.jpg |
|  0.00 |  0 | 20161206 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/1E/CvkBIlhGxAuAfQr8AAFatVZ2sFk337.jpg |
|  0.00 |  0 | 20161205 | 2154FDCDA51A4257811F1EA886AACD14|http://testxxx.cn/group1/M00/00/1D/CvkBIlhGKy-AU9guAAGm4jFhmoU601.jpg |
| 20000.00 |  3 | 20161204 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/23/CvkBIVhEIDGAMPuIAAH6chL6Wo8684.jpg |
| 20275.00 |  4 | 20161203 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/21/CvkBIVhCyrSAE-uGAAGf0CWFbZM991.jpg |
| 3988.00 |  1 | 20161202 | 98FDB31FE4B04C21BC7EBE8A22981DA0|http://testxxx.cn/group1/M00/00/19/CvkBIlhCI7mAUN_9AAIsSLMhcns351.jpg |
| 4460.00 |  1 | 20161201 | 2154FDCDA51A4257811F1EA886AACD14|http://testxxx.cn/group1/M00/00/17/CvkBIlhAKwmACroNAAGpJUqVqIA247.jpg |
| 10498.00 |  2 | 20161130 | 2154FDCDA51A4257811F1EA886AACD14|http://testxxx.cn/group1/M00/00/16/CvkBIlg-3euAbsd5AAGr-r7GCH0254.jpg |
| 11080.00 |  2 | 20161129 | 2154FDCDA51A4257811F1EA886AACD14|http://testxxx.cn/group1/M00/00/1C/CvkBIVg9i6WAD4Z0AAHLB1yISaQ864.jpg |
| 6100.00 |  1 | 20161128 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/1B/CvkBIVg8OHGABTZOAAG1ZWoLoXY932.jpg |
| 5580.00 |  1 | 20161127 | 98FDB31FE4B04C21BC7EBE8A22981DA0|http://testxxx.cn/group1/M00/00/19/CvkBIVg65aKAcRWWAAFnaqaodKs660.jpg |
| 32630.00 |  2 | 20161126 | 2154FDCDA51A4257811F1EA886AACD14|http://testxxx.cn/group1/M00/00/18/CvkBIVg5kveALns0AAHLB1yISaQ850.jpg |
| 9800.00 |  1 | 20161125 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/17/CvkBIVg4Qg2AMqoNAAH--He3hsg726.jpg |
| 32500.00 |  2 | 20161124 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/16/CvkBIVg27_OAAV5OAAE8vRiZWHs684.jpg |
| 2700.00 |  1 | 20161123 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/0E/CvkBIlg2T4OAL3t5AAFsAWaUI98731.jpg |
| 4580.00 |  1 | 20161122 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/14/CvkBIVg0-UeAFDr_AAIBY_LNIxs656.jpg |
| 14120.00 |  1 | 20161121 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/0B/CvkBIlgy_EeAaPdBAAHeyO5nxeo952.jpg |
| 41510.00 |  2 | 20161120 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/12/CvkBIVgyYRKAZKi3AAGEp_IGjVM389.jpg |
| 7800.00 |  2 | 20161118 | C91D5E7905BA44C8A14045C9C228157F|http://testxxx.cn/group1/M00/00/09/CvkBIlgw_viAFHiPAAH0MZwoiCE530.jpg |
+-----------+-------+----------+------------------------------------------------------------------------------------------------------------+
48 rows in set (0.75 sec)
mysql>

View the current profile records, mainly to obtain the Query_ID value

mysql> show profiles;
+----------+------------+------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------------------+
| Query_ID | Duration | Query                            |
+----------+------------+-------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------------------------
-------------------------------------------------------------------------------------------------------+
|  1 | 0.00009250 | show warning                        |
|  2 | 0.00013125 | show warnings               |
|  3 | 0.00014375 | set profiling=1               |
|  4 | 0.75458525 | SELECT SQL_NO_CACHE
    t1.amount,
    t1.count,
    t1.date ,
     (SELECT (CONCAT(t2.APPROVE_ID,'|' ,t2.PATH)) AS RECEIPT FROM TB_BIS_MERCHANT_SETTLEMENT t2 
     WHERE t2.`MERCHANT_ID` = t1.`MERCHANT_ID` AND t2.`DATE`=t1.DATE AND t2.APPROVE_STATUS=5) AS r |
+----------+------------+----------------------------------------------------------------------------------------------------------------------
-------------------------------------------------------------------------------------------------------------------------------------------------
---------------------------------------+
4 rows in set, 1 warning (0.00 sec)
mysql>

View the tracking record of the Query_ID 4 just executed

mysql> show profile for query 4;
+--------------------+----------+
| Status    | Duration |
+--------------------+----------+
| executing   | 0.000017 |
| Sending data  | 0.018048 |
| executing   | 0.000028 |
| Sending data  | 0.018125 |
| executing   | 0.000022 |
| Sending data  | 0.015749 |
| executing   | 0.000017 |
| Sending data  | 0.015633 |
| executing   | 0.000017 |
| Sending data  | 0.015382 |
| executing   | 0.000015 |
| Sending data  | 0.015707 |
| executing   | 0.000023 |
| Sending data  | 0.015890 |
| executing   | 0.000022 |
| Sending data  | 0.015908 |
| executing   | 0.000017 |
| Sending data  | 0.015761 |
| executing   | 0.000022 |
| Sending data  | 0.015542 |
| executing   | 0.000014 |
| Sending data  | 0.015561 |
| executing   | 0.000016 |
| Sending data  | 0.015546 |
| executing   | 0.000037 |
| Sending data  | 0.015555 |
| executing   | 0.000015 |
| Sending data  | 0.015779 |
| executing   | 0.000026 |
| Sending data  | 0.015815 |
| executing   | 0.000015 |
| Sending data  | 0.015468 |
| executing   | 0.000015 |
| Sending data  | 0.015457 |
| executing   | 0.000015 |
| Sending data  | 0.015457 |
| executing   | 0.000014 |
| Sending data  | 0.015500 |
| executing   | 0.000014 |
| Sending data  | 0.015557 |
| executing   | 0.000015 |
| Sending data  | 0.015537 |
| executing   | 0.000014 |
| Sending data  | 0.015395 |
| executing   | 0.000021 |
| Sending data  | 0.015416 |
| executing   | 0.000014 |
| Sending data  | 0.015416 |
| executing   | 0.000014 |
| Sending data  | 0.015399 |
| executing   | 0.000023 |
| Sending data  | 0.015407 |
| executing   | 0.000014 |
| Sending data  | 0.015585 |
| executing   | 0.000014 |
| Sending data  | 0.015385 |
| executing   | 0.000014 |
| Sending data  | 0.015412 |
| executing   | 0.000014 |
| Sending data  | 0.015408 |
| executing   | 0.000014 |
| Sending data  | 0.015753 |
| executing   | 0.000014 |
| Sending data  | 0.015376 |
| executing   | 0.000014 |
| Sending data  | 0.015416 |
| executing   | 0.000019 |
| Sending data  | 0.015368 |
| executing   | 0.000014 |
| Sending data  | 0.015481 |
| executing   | 0.000015 |
| Sending data  | 0.015619 |
| executing   | 0.000015 |
| Sending data  | 0.015662 |
| executing   | 0.000016 |
| Sending data  | 0.015574 |
| executing   | 0.000015 |
| Sending data  | 0.015566 |
| executing   | 0.000015 |
| Sending data  | 0.015488 |
| executing   | 0.000013 |
| Sending data  | 0.015493 |
| executing   | 0.000015 |
| Sending data  | 0.015386 |
| executing   | 0.000015 |
| Sending data  | 0.015485 |
| executing   | 0.000018 |
| Sending data  | 0.015760 |
| executing   | 0.000014 |
| Sending data  | 0.015386 |
| executing   | 0.000015 |
| Sending data  | 0.015418 |
| executing   | 0.000014 |
| Sending data  | 0.015458 |
| end    | 0.000016 |
| query end   | 0.000019 |
| closing tables  | 0.000018 |
| freeing items  | 0.000825 |
| logging slow query | 0.000067 |
| cleaning up  | 0.000025 |
+--------------------+----------+
100 rows in set, 1 warning (0.00 sec)
mysql>

According to the analysis results, we can see that there is a large amount of Sending data consumption , and it is continuous. This can be judged to be caused by a subquery, so in this case, the subquery is not suitable and the efficiency is too low. So what should be used to avoid it? Use group by + left join to rewrite

mysql> SELECT SQL_NO_CACHE DISTINCT
 ->     t1.amount,
 ->     t1.count,
 ->     t1.date, GROUP_CONCAT(CONCAT(t2.APPROVE_ID,'|' ,t2.PATH)) AS RECEIPT 
 ->    FROM
 ->     TB_BIS_MERCHANT_TURNOVER t1 LEFT JOIN TB_BIS_MERCHANT_SETTLEMENT t2 ON t2.
 `MERCHANT_ID` = t1.`MERCHANT_ID` AND t2.`DATE`=t1.DATE AND t2.APPROVE_STATUS=5
 ->    WHERE t1.MERCHANT_ID='64884DE062BC11E682B00017FA000202'
 ->    GROUP BY t1.amount,
 ->     t1.count,
 ->     t1.date
 ->         ORDER BY t1.date DESC
 -> 
 -> LIMIT 0,100;
+-----------+-------+----------+------------------------------------------------------------------------------------------------------------+
| amount | count | date  | RECEIPT                         |
+-----------+-------+----------+------------------------------------------------------------------------------------------------------------+
| 15800.00 |  1 | 20170105 | 0DDFD555F93B45BEB0905B1E6DE89D29|http://testxxx.cn/group1/M00/00/49/CvkBIlhu-yqABqmAABYR7dHOmno819.jpg |
| 1245.00 |  1 | 20170104 | 0DDFD555F93B45BEB0905B1E6DE89D29|http://testxxx.cn/group1/M00/00/4F/CvkBIVhtpSeAI_YHAADNjq7TPq8244.jpg |
| 14766.00 |  4 | 20170103 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/45/CvkBIlhrrf6AQ5uIAAEobJv68FU398.jpg |
| 32449.00 |  2 | 20170102 | 0DDFD555F93B45BEB0905B1E6DE89D29|http://testxxx.cn/group1/M00/00/4C/CvkBIVhrDguAfaMIABjKB9uvu04477.jpg |
| 37246.00 |  5 | 20170101 | 0DDFD555F93B45BEB0905B1E6DE89D29|http://testxxx.cn/group1/M00/00/4A/CvkBIVhpCnGASEyLAAEu6l9SI0o812.jpg |
| 105094.00 |  2 | 20161231 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/49/CvkBIVhnwp-ALIvWAAEAaGPayjg732.jpg |
| 88032.00 |  3 | 20161230 | 98FDB31FE4B04C21BC7EBE8A22981DA0|http://testxxx.cn/group1/M00/00/47/CvkBIVhmaqSAHcEZAAFAyS8Zx8Q067.jpg |
| 3845.00 |  1 | 20161229 | 98FDB31FE4B04C21BC7EBE8A22981DA0|http://testxxx.cn/group1/M00/00/3F/CvkBIlhl206AaS-FAAFMhvX8PYY578.jpg |
| 2118.00 |  4 | 20161228 | 2154FDCDA51A4257811F1EA886AACD14|http://testxxx.cn/group1/M00/00/3D/CvkBIlhjxhyAMOfhAAD8wUzTUUY855.jpg |
| 2980.00 |  1 | 20161227 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/3B/CvkBIlhicfCAFmwgAAE9ULPqEJ4030.jpg |
| 1080.00 |  1 | 20161226 | 667E240C44B4469892C261CE9243A8C3|http://testxxx.cn/group1/M00/00/42/CvkBIVhhy6iAMm8tAAFHOT5zBiM875.jpg |
| 2980.00 |  1 | 20161225 | 0DDFD555F93B45BEB0905B1E6DE89D29|http://testxxx.cn/group1/M00/00/40/CvkBIVhfzCWAdw2LAAFpDXmwio4327.jpg |
| 10201.00 |  1 | 20161224 | 98FDB31FE4B04C21BC7EBE8A22981DA0|http://testxxx.cn/group1/M00/00/38/CvkBIlhfJfKAIoBiAADqgbF1pBo054.jpg |
| 3003.00 |  4 | 20161223 | 98FDB31FE4B04C21BC7EBE8A22981DA0|http://testxxx.cn/group1/M00/00/3D/CvkBIVhdMHeAQi8cAAGAOQTgxLo422.jpg |
| 2698.00 |  1 | 20161222 | 98FDB31FE4B04C21BC7EBE8A22981DA0|http://testxxx.cn/group1/M00/00/3C/CvkBIVhb2U2AXWRuAAEc4LIr2nc172.jpg |
| 990.00 |  1 | 20161221 | 98FDB31FE4B04C21BC7EBE8A22981DA0|http://testxxx.cn/group1/M00/00/3B/CvkBIVhbM6aAGMQAAAEQ9ptn0FU333.jpg |
| 1427.00 |  1 | 20161220 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/31/CvkBIlhZNJqAAsvWAAGuJ6g1pyU541.jpg |
| 2465.00 |  1 | 20161219 | 2154FDCDA51A4257811F1EA886AACD14|http://testxxx.cn/group1/M00/00/30/CvkBIlhX4_mAfn-SAAEptH1Fyp8152.jpg |
| 2360.00 |  1 | 20161218 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/2F/CvkBIlhWl_-AclhbAAGLv79hoh8428.jpg |
| 3998.00 |  1 | 20161217 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/35/CvkBIVhVSLGAFct_AAFQRetyWnc285.jpg |
|  0.00 |  0 | 20161216 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/2D/CvkBIlhU8g-AXywcAAGn1gdsQQc959.jpg |
|  0.00 |  0 | 20161215 | 98FDB31FE4B04C21BC7EBE8A22981DA0|http://testxxx.cn/group1/M00/00/2A/CvkBIlhSmryAZXITAG-zN3WQv4c789.jpg |
| 9900.00 |  1 | 20161214 | 98FDB31FE4B04C21BC7EBE8A22981DA0|http://testxxx.cn/group1/M00/00/31/CvkBIVhRTrOALwG6AAE_csC3lvk695.jpg |
| 4320.00 |  1 | 20161213 | 2154FDCDA51A4257811F1EA886AACD14|http://testxxx.cn/group1/M00/00/28/CvkBIlhQrzCAfApEAAFKbHqkH3w634.jpg |
| 8760.00 |  2 | 20161212 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/26/CvkBIlhOqjeAO1BdAAGHdajOU2E697.jpg |
| 213335.00 |  4 | 20161211 | 2154FDCDA51A4257811F1EA886AACD14|http://testxxx.cn/group1/M00/00/2D/CvkBIVhNYQSAfxXgAAHZL9a8Nrs596.jpg |
| 47104.00 |  5 | 20161210 | 98FDB31FE4B04C21BC7EBE8A22981DA0|http://testxxx.cn/group1/M00/00/2C/CvkBIVhMsPSAAnrAAAETxX9fCuw946.jpg |
| 6100.00 |  1 | 20161209 | 98FDB31FE4B04C21BC7EBE8A22981DA0|http://testxxx.cn/group1/M00/00/23/CvkBIlhLfXOAClJVAAFmuoqBI5o264.jpg |
| 13515.00 |  2 | 20161208 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/21/CvkBIlhJZ06AbuaNAAGg7Bz3OsA569.jpg |
| 26769.00 |  4 | 20161207 | 98FDB31FE4B04C21BC7EBE8A22981DA0|http://testxxx.cn/group1/M00/00/20/CvkBIlhIGgeAdNxuAAETxX9fCuw408.jpg |
|  0.00 |  0 | 20161206 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/1E/CvkBIlhGxAuAfQr8AAFatVZ2sFk337.jpg |
|  0.00 |  0 | 20161205 | 2154FDCDA51A4257811F1EA886AACD14|http://testxxx.cn/group1/M00/00/1D/CvkBIlhGKy-AU9guAAGm4jFhmoU601.jpg |
| 20000.00 |  3 | 20161204 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/23/CvkBIVhEIDGAMPuIAAH6chL6Wo8684.jpg |
| 20275.00 |  4 | 20161203 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/21/CvkBIVhCyrSAE-uGAAGf0CWFbZM991.jpg |
| 3988.00 |  1 | 20161202 | 98FDB31FE4B04C21BC7EBE8A22981DA0|http://testxxx.cn/group1/M00/00/19/CvkBIlhCI7mAUN_9AAIsSLMhcns351.jpg |
| 4460.00 |  1 | 20161201 | 2154FDCDA51A4257811F1EA886AACD14|http://testxxx.cn/group1/M00/00/17/CvkBIlhAKwmACroNAAGpJUqVqIA247.jpg |
| 10498.00 |  2 | 20161130 | 2154FDCDA51A4257811F1EA886AACD14|http://testxxx.cn/group1/M00/00/16/CvkBIlg-3euAbsd5AAGr-r7GCH0254.jpg |
| 11080.00 |  2 | 20161129 | 2154FDCDA51A4257811F1EA886AACD14|http://testxxx.cn/group1/M00/00/1C/CvkBIVg9i6WAD4Z0AAHLB1yISaQ864.jpg |
| 6100.00 |  1 | 20161128 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/1B/CvkBIVg8OHGABTZOAAG1ZWoLoXY932.jpg |
| 5580.00 |  1 | 20161127 | 98FDB31FE4B04C21BC7EBE8A22981DA0|http://testxxx.cn/group1/M00/00/19/CvkBIVg65aKAcRWWAAFnaqaodKs660.jpg |
| 32630.00 |  2 | 20161126 | 2154FDCDA51A4257811F1EA886AACD14|http://testxxx.cn/group1/M00/00/18/CvkBIVg5kveALns0AAHLB1yISaQ850.jpg |
| 9800.00 |  1 | 20161125 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/17/CvkBIVg4Qg2AMqoNAAH--He3hsg726.jpg |
| 32500.00 |  2 | 20161124 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/16/CvkBIVg27_OAAV5OAAE8vRiZWHs684.jpg |
| 2700.00 |  1 | 20161123 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/0E/CvkBIlg2T4OAL3t5AAFsAWaUI98731.jpg |
| 4580.00 |  1 | 20161122 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/14/CvkBIVg0-UeAFDr_AAIBY_LNIxs656.jpg |
| 14120.00 |  1 | 20161121 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/0B/CvkBIlgy_EeAaPdBAAHeyO5nxeo952.jpg |
| 41510.00 |  2 | 20161120 | EC481757CFDB445092D16D6B616350C8|http://testxxx.cn/group1/M00/00/12/CvkBIVgyYRKAZKi3AAGEp_IGjVM389.jpg |
| 7800.00 |  2 | 20161118 | C91D5E7905BA44C8A14045C9C228157F|http://testxxx.cn/group1/M00/00/09/CvkBIlgw_viAFHiPAAH0MZwoiCE530.jpg |
+-----------+-------+----------+------------------------------------------------------------------------------------------------------------+
48 rows in set (0.15 sec)
mysql>

You can see that the execution time becomes 0.15 seconds, which improves the efficiency by 5 times.

mysql> show profile for query 8;
+-------------------------------+----------+
| Status      | Duration |
+-------------------------------+----------+
| starting      | 0.000125 |
| checking permissions   | 0.000015 |
| checking permissions   | 0.000014 |
| Opening tables    | 0.000029 |
| init       | 0.000055 |
| System lock     | 0.000020 |
| Waiting for query cache lock | 0.000013 |
| System lock     | 0.000050 |
| optimizing     | 0.000023 |
| statistics     | 0.000087 |
| preparing      | 0.000066 |
| Creating tmp table   | 0.000062 |
| Creating tmp table   | 0.000028 |
| Sorting result    | 0.000016 |
| executing      | 0.000012 |
| Sending data     | 0.148283 |
| Creating sort index   | 0.000342 |
| Creating sort index   | 0.000223 |
| end       | 0.000015 |
| query end      | 0.000046 |
| removing tmp table   | 0.000017 |
| query end      | 0.000012 |
| removing tmp table   | 0.000062 |
| query end      | 0.000015 |
| closing tables    | 0.000017 |
| freeing items     | 0.000019 |
| removing tmp table   | 0.000025 |
| freeing items     | 0.000016 |
| Waiting for query cache lock | 0.000012 |
| freeing items     | 0.000915 |
| Waiting for query cache lock | 0.000015 |
| freeing items     | 0.000011 |
| storing result in query cache | 0.000013 |
| cleaning up     | 0.000024 |
+-------------------------------+----------+
34 rows in set, 1 warning (0.00 sec)
mysql>

You can see that there is only one consumption of | Sending data | 0.148283 |, so the efficiency improves very quickly. Extension part

SELECT 
 NAME,
 VALUE 
FROM
 v $ parameter 
WHERE NAME IN (
 'pga_aggregate_target',
 'sga_target'
 ) 
UNION
SELECT 
 'maximum PGA allocated' AS NAME,
 TO_CHAR (VALUE) AS VALUE 
FROM
 v $ pgastat 
WHERE NAME = 'maximum PGA allocated' ;

rrree

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