Hello, it may be a simple question, but I can't get to it: Why this simple query does not use the PRIMARY key (which is oai_ui)?
mysql> explain select * from idb_metadata where oai_ui like 'doi:10.1088/0%'; +--------------+------+---------------+------+---------+------+--------+------------+ | table | type | possible_keys | key | key_len | ref | rows | Extra | +--------------+------+---------------+------+---------+------+--------+------------+ | idb_metadata | ALL | PRIMARY | NULL | NULL | NULL | 178035 | where used | +--------------+------+---------------+------+---------+------+--------+------------+ While this is correctly using it.... mysql> explain select oai_ui from idb_metadata where oai_ui like 'doi:10.1088/0%'; +--------------+-------+---------------+---------+---------+------+--------+-------------------------+ | table | type | possible_keys | key | key_len | ref | rows | Extra | | +--------------+-------+---------------+---------+---------+------+--------+-------------------------+ | idb_metadata | range | PRIMARY | PRIMARY | 50 | NULL | 137387 | where |used; Using index | +--------------+-------+---------------+---------+---------+------+--------+-------------------------+ The change is just that I select * instead of the column itself. Thanks in advance to whoever can help.. running crazy in tuning, Thanks Fabrizio Nesti -- MediaLab -- SISSA -- IT PS: System info: Server: 3.23.38-max-log Table desc (it has 178035 records): mysql> desc idb_metadata; +-------------+---------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------------+---------------+------+-----+---------+-------+ | oai_ui | varchar(50) | | PRI | | | | download | date | YES | | NULL | | | datestamp | date | YES | | NULL | | | updated | timestamp(14) | YES | | NULL | | | submission | date | YES | MUL | NULL | | | replacement | date | YES | MUL | NULL | | | title | text | YES | | NULL | | | abstract | text | YES | | NULL | | | comment | text | YES | | NULL | | | journal | tinytext | YES | | NULL | | | url | tinytext | YES | | NULL | | | type | tinytext | YES | | NULL | | | language | tinytext | YES | | NULL | | | rights | tinytext | YES | | NULL | | | publisher | tinytext | YES | | NULL | | | contributor | tinytext | YES | | NULL | | | format | tinytext | YES | | NULL | | | source | tinytext | YES | | NULL | | | relation | tinytext | YES | | NULL | | | coverage | tinytext | YES | | NULL | | | profiles | tinyint(4) | YES | | 1 | | +-------------+---------------+------+-----+---------+-------+ --------------------------------------------------------------------- Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail <[EMAIL PROTECTED]> To unsubscribe, e-mail <[EMAIL PROTECTED]> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
