[MySQL 友情协助] ERROR 3 (HY000): Error writing file '/dev/shm/MYHTwgxT' (Errcode: 2

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　　朋友线上DB执行SQL报错：ERROR 3 (HY000): Error writing file '/dev/shm/MYHTwgxT' (Errcode: 28)
　　
　　让朋友取得dev组run 过的sql，执行explain，如下：
　　mysql> explainselect count(*) from ( select STG_ITEM.ITEM_ID from (selectitem_label.item_id,item_label.revision from catalog.item_label item_label innerjoin (select max(item_label.effective_date) aseffective_date,item_label.item_idfrom catalog.item_label inner joincatalog.item item on item.item_id=item_label.item_id anditem.revision=item_label.revision whereitem_label.EFFECTIVE_DATE>='2013-01-01 00:00:00' ANDitem_label.EFFECTIVE_DATE < '2014-01-14 00:00:00' and label='PROD' groupby2) stg on item_label.effective_date=stg.effective_date anditem_label.item_id=stg.item_id and item_label.LABEL='PROD' ) STG_ITEM innerjoin catalog.attribute_set attr_set onattr_set.ATTRIBUTABLE_ENTITY_ID=STG_ITEM.ITEM_ID andattr_set.ATTRIBUTABLE_ENTITY_REVISION=STG_ITEM.REVISIONleft outer joincatalog.public_attribute attr onattr.ATTRIBUTE_SET_ID=attr_set.ATTRIBUTE_SET_ID whereattr_set.ATTRIBUTABLE_ENTITY_TYPE='ITEM' and attr_set.ATTRIBUTE_SET_TYPE in('LOCALE','ACTION','COUNTRY','BASE','CUSTOM','EVENT','FULFILLMENT','PUBLISHING','RESTRICTION')groupby STG_ITEM.ITEM_ID, STG_ITEM.REVISION, attr_set.ATTRIBUTE_SET_ID,attr_set.ATTRIBUTABLE_ENTITY_ID, attr_set.ATTRIBUTABLE_ENTITY_TYPE,attr_set.ATTRIBUTABLE_ENTITY_REVISION, attr_set.ATTRIBUTE_SET_TYPE, attr_set.ATTRIBUTE_SET_KEY,attr.ATTRIBUTE_NAME, attr.ATTRIBUTE_VALUE) cnt;
　　ERROR 3 (HY000): Error writing file '/dev/shm/MYHTwgxT' (Errcode: 28)

　　让朋友马上去检查tmp目录，发现磁盘tmp磁盘目录满了:
　　
　　[xx@xx01]$ df -h
　　FilesystemSize Used Avail Use% Mounted on
　　/dev/mapper/Sys-root1008M 235M 723M 25% /
　　tmpfs16G 16G 139M 100%/dev/shm
　　/dev/vda1194M 32M 153M 18% /boot
　　/dev/mapper/Sys-home4.0G 145M 3.6G 4% /home

　　

　　
　　看到此情况，我给了2个建议：
　　1, increase the size of/dev/shm, maybe 200G is enough.
2, this sql istoo complex to run, ptimize the sql, and run the more concise sql in theint map database, for example:
When I change the where clause“item_label.EFFECTIVE_DATE>='2013-01-01 00:00:00' ” to“item_label.EFFECTIVE_DATE>='2013-03-01 00:00:00' ”, this sql scriptcan run and get a result, as follows:
mysql> select count(*) from ( selectSTG_ITEM.ITEM_ID from (select item_label.item_id,item_label.revision fromcatalog.item_label item_label inner join (select max(item_label.effective_date)as effective_date,item_label.item_idfrom catalog.item_label inner joincatalog.item item on item.item_id=item_label.item_id anditem.revision=item_label.revision whereitem_label.EFFECTIVE_DATE>='2013-03-01 00:00:00'AND item_label.EFFECTIVE_DATE < '2014-01-14 00:00:00' andlabel='PROD' group by 2) stg on item_label.effective_date=stg.effective_dateand item_label.item_id=stg.item_idand item_label.LABEL='PROD' ) STG_ITEM innerjoin catalog.attribute_set attr_set onattr_set.ATTRIBUTABLE_ENTITY_ID=STG_ITEM.ITEM_ID andattr_set.ATTRIBUTABLE_ENTITY_REVISION=STG_ITEM.REVISION left outer joincatalog.public_attribute attr on attr.ATTRIBUTE_SET_ID=attr_set.ATTRIBUTE_SET_IDwhereattr_set.ATTRIBUTABLE_ENTITY_TYPE='ITEM' and attr_set.ATTRIBUTE_SET_TYPEin('LOCALE','ACTION','COUNTRY','BASE','CUSTOM','EVENT','FULFILLMENT','PUBLISHING','RESTRICTION')group by STG_ITEM.ITEM_ID, STG_ITEM.REVISION, attr_set.ATTRIBUTE_SET_ID,attr_set.ATTRIBUTABLE_ENTITY_ID,attr_set.ATTRIBUTABLE_ENTITY_TYPE,attr_set.ATTRIBUTABLE_ENTITY_REVISION, attr_set.ATTRIBUTE_SET_TYPE,attr_set.ATTRIBUTE_SET_KEY, attr.ATTRIBUTE_NAME, attr.ATTRIBUTE_VALUE ) cnt;
+----------+
| count(*) |
+----------+
| 58739 |
+----------+
1 row in set (7.45 sec)