Queries explained

gistfile1.txt

Related to: http://stackoverflow.com/questions/13056049/how-to-specify-the-from-tables-in-sqlalchemy-subqueries

1st Query:

EXPLAIN
SELECT MAX(d2.id)
FROM my_table d1
JOIN my_table d2
ON d2.id < d1.id
WHERE d1.id IN (111283470, 111283370, 111282470)
GROUP BY d1.id;

"id"	"select_type"	"table"	"type"	"possible_keys"	"key"	"key_len"	"ref"	"rows"	"Extra"
"1"	"SIMPLE"	"d1"	"range"	"PRIMARY"	"PRIMARY"	"8"	\N	"3"	"Using where; Using index; Using temporary; Using filesort"
"1"	"SIMPLE"	"d2"	"index"	"PRIMARY"	"fk_severity"	"1"	\N	"17832029"	"Using where; Using index; Using join buffer"

2nd Query:
EXPLAIN
SELECT d2.id
FROM my_table d1, my_table d2
WHERE d2.id =
(SELECT d3.id FROM my_table d3 WHERE d3.id < d1.id ORDER BY d3.id DESC LIMIT 1)
AND d1.id IN (111283470, 111283370, 111282470);

"id"	"select_type"	"table"	"type"   	"possible_keys"	"key"    	"key_len"	"ref"	"rows"	"Extra"
"1"	"PRIMARY"	"d1"	"range"   	"PRIMARY"	"PRIMARY"	"8"      	\N	"3"	"Using where; Using index"
"1"	"PRIMARY"	"d2"	"eq_ref"  	"PRIMARY"	"PRIMARY"	"8"      	"func"	"1"	"Using where; Using index"
"2"	"DEP. SUBQ."	"d3"	"index"  	"PRIMARY"	"PRIMARY"	"8"      	\N	"1"	"Using where; Using index"

("DEP. SUBQ." stands for "DEPENDENT SUBQUERY", was abbreviated just to keep the table formatting cleaner)