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mysql text datatype SELECT query slow even with tmp dir on tmpfs
Posted by: Muhammad Omair
Date: February 22, 2016 08:36AM

I have a SELECT five table join query that has TEXT field in it. Even though the mysql tmp dir is mounted on tmpfs the SELECT query is slow. Below is the PROFILE of the SELECT query and the tmpfs configuration. Does anyone know what could be the issue here?

tmpfs /var/lib/mysqltmpfs tmpfs size=10g,uid=mysql,gid=mysql,mode=0755 0 0


mysql> SHOW PROFILE;
+----------------------+----------+
| Status | Duration |
+----------------------+----------+
| starting | 0.000214 |
| checking permissions | 0.000047 |
| checking permissions | 0.000044 |
| checking permissions | 0.000044 |
| checking permissions | 0.000044 |
| checking permissions | 0.000046 |
| Opening tables | 0.000091 |
| init | 0.000096 |
| System lock | 0.000055 |
| optimizing | 0.000061 |
| statistics | 0.000282 |
| preparing | 0.000066 |
| Creating tmp table | 0.000116 |
| executing | 0.000046 |
| Sending data | 0.188435 |
| end | 0.000225 |
| removing tmp table | 0.123960 |
| end | 0.000232 |
| query end | 0.000058 |
| closing tables | 0.000098 |
| freeing items | 0.000107 |
| cleaning up | 0.000095 |
+----------------------+----------+

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mysql text datatype SELECT query slow even with tmp dir on tmpfs
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February 22, 2016 08:36AM


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