Hi,
The statement will do a Full table scan, because of the following things :
Not using "Where" clause, and selecting "all columns (*)" within the query.
Filesort is used since no index is used, use a where clause with condition
on column which is indexed and notice the explain plan. Also you can
Hi,
I’m attempting to optimize a join and am having a difficult time using
multiple columns from a composite index. The second column of the composite
key is being used when tested for equality, but not for IN or BETWEEN
criteria.
As an example, say that I’m searching two tables: portfolio and tr
my reason for create a key on "qg_sort" was primary
for this query - but why is here 'filesort' used?
mysql> EXPLAIN SELECT * FROM cms1_quickbar_groups ORDER BY qg_sort ASC;
++-+--+--+---+--+-+--+--++
| id | se
On 10.07.2012 13:16, Darek Maciera wrote:
2012/7/10 Ananda Kumar :
can u show the explain plan for your query
Thanks, for reply!
Sure:
mysql> EXPLAIN SELECT * FROM books WHERE LOWER(ksd)=LOWER('4204661375');
That's definitely not the query you showed the first time around. The
query you'
you are using a function-LOWER, which will not make use of the unique key
index on ksd.
Mysql does not support function based index, hence your query is doing a
FULL TABLE scan and taking more time.
On Tue, Jul 10, 2012 at 4:46 PM, Darek Maciera wrote:
> 2012/7/10 Ananda Kumar :
> > can u show th
2012/7/10 Ananda Kumar :
> can u show the explain plan for your query
>
Thanks, for reply!
Sure:
mysql> EXPLAIN SELECT * FROM books WHERE LOWER(ksd)=LOWER('4204661375');
++-+-+--+---+--+-+--++-+
| id | se
can u show the explain plan for your query
On Tue, Jul 10, 2012 at 2:59 PM, Darek Maciera wrote:
> Hello,
>
> I have table:
>
> mysql> DESCRIBE books;
>
> |id |int(255) | NO | PRI |
> NULL | auto_increment |
> | idu
Hello,
I have table:
mysql> DESCRIBE books;
|id |int(255) | NO | PRI |
NULL | auto_increment |
| idu | int(255) | NO | MUL | NULL
| ksd | char(15) | YES |
