CODEWITHSUNDEEP
mysqlsqlindexingexplainpartition
Aamir
Aamir

Reputation: 758

why explain partition shows first partition in every select query?

I have a table named edr on mysql 5.1.6* version. I have partitioned the table using alter -

ALTER TABLE edr PARTITION BY RANGE (TO_DAYS(eventDate))
 (
   PARTITION apr25 VALUES LESS THAN (TO_DAYS('2014-04-26')),
   PARTITION apr26_30 VALUES LESS THAN (TO_DAYS('2014-05-01')),
   PARTITION may01_05 VALUES LESS THAN (TO_DAYS('2014-05-06')),
   PARTITION may06_10 VALUES LESS THAN (TO_DAYS('2014-05-11')),
   PARTITION may11_15 VALUES LESS THAN (TO_DAYS('2014-05-16')),
   PARTITION may16_20 VALUES LESS THAN (TO_DAYS('2014-05-21')),
   PARTITION may21_25 VALUES LESS THAN (TO_DAYS('2014-05-26')),
   PARTITION may26_31 VALUES LESS THAN (TO_DAYS('2014-06-01')),
   PARTITION june01_05 VALUES LESS THAN (TO_DAYS('2014-06-06')),
   PARTITION june06_10 VALUES LESS THAN (TO_DAYS('2014-06-11')),
   PARTITION june11_15 VALUES LESS THAN (TO_DAYS('2014-06-16')));

now when I am running any query for example:

explain partitions select count(*) from edr where eventdate > '2014-05-21';

it gives me output for partitions as - apr25,may21_25, may26_31, jun01_05,jun_06_10,jun11_15. Here in partition apr25 there is no record for such where condition.

please let me know is any thing wrong in above query or its a partition problem.

Upvotes: 2

Views: 453

Answers (1)

imilbaev
imilbaev

Reputation: 854

It is MySQL bug: explained here. Try to create a first partition that contains values less than (0)

PARTITION unused VALUES LESS THAN (0);

Upvotes: 1

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