Re: Partition behaiour seems abnormal in range partition

[Rick James]

Are the partitions of similar size?

To further debug...

SELECT * FROM information_schema.PARTITIONs WHERE table_schema = 'PART_SAMPLE';
(or something like that)

EXPLAIN PARTITIONS SELECT ... -- for a fast partition; then for a slow partition.

You may need to do an OPTIMIZE. Probably only once. Probably it will take a long time (and lock the table).