I still don't understand the matter. "teste" is a unique index, because part of it is unique. But it is not declared as unique, and MariaDB is not suppose to read our minds. The query written by Reindl looks realistic, but it would use the primary key, and I would be disappointed if it used "teste". Are we talking about real-world needs, or just speculation? Federico -------------------------------------------- Mar 23/6/15, Reindl Harald <h.reindl@thelounge.net> ha scritto: Oggetto: Re: [Maria-discuss] doubt about index A: "Maria Discuss" <maria-discuss@lists.launchpad.net> Data: Martedì 23 giugno 2015, 01:13 Am 23.06.2015 um 00:53 schrieb Roberto Spadim:
2015-06-22 19:47 GMT-03:00 Reindl Harald <h.reindl@thelounge.net <mailto:h.reindl@thelounge.net>>:
Am 23.06.2015 um 00:43 schrieb Roberto Spadim:
when i have a
when i have a index with primary key + any other column, does mariadb consider that it's unique too?
if it is defined as unique key yes
what is "index with
hi guys, i`m with a doubt... primary key i know that's a unique key primary key + any other column"?
for example
create table x( i int, b int, c int, d int , e int, ... primary key(i), key teste(b,i) )
the test index is primary key (i column) + any other column (b,c,d,e,...)
these are two indexes the second one is completly nosense as long your qquery is not in the form of "where b=x and i=y" and even "where i=y and b=x" won't be able to use it
you have two keys in that case and the select uses one of them
yeap but some search algorithms use unique key/non unique key information to improve search right?
which part of the documentation says that?
does it consider that any index that contains a unique index columns +
anyother column as "unique" why should it? it must not just because they are not
i`m thinking more about SELECT optimization
how does it matter if a key is unique or not for select optimization?
select "where i=1" should return 0/1 rows (it's unique),
"where b=1" should return 0+ rows, but "where b=1 and i=1" should return 0/1 rows
it don't matter at all, these are two seperate indexes -----Segue allegato----- _______________________________________________ Mailing list: https://launchpad.net/~maria-discuss Post to : maria-discuss@lists.launchpad.net Unsubscribe : https://launchpad.net/~maria-discuss More help : https://help.launchpad.net/ListHelp