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Re: Select last row that is less than or equal to a date
Posted by: David Marcus
Date: January 26, 2013 09:35AM

Thank you, Rick. I tried it with and without the limit. See below. It
looks like MySQL is finding the one record by finding it in the index,
so it is doing a good job. Is that correct? Are the 9
Handler_read_rnd_next's from reading the index?

SHOW SESSION STATUS LIKE 'Handler%';
"Variable_name","Value"
"Handler_commit","0"
"Handler_delete","0"
"Handler_discover","0"
"Handler_prepare","0"
"Handler_read_first","0"
"Handler_read_key","0"
"Handler_read_last","0"
"Handler_read_next","0"
"Handler_read_prev","0"
"Handler_read_rnd","0"
"Handler_read_rnd_next","2"
"Handler_rollback","0"
"Handler_savepoint","0"
"Handler_savepoint_rollback","0"
"Handler_update","0"
"Handler_write","1"

select * from History where HistoryPlayer = 59161 and HistoryDate <= '2012-01-01' order by HistoryDate desc limit 0,1;

SHOW SESSION STATUS LIKE 'Handler%';
"Variable_name","Value"
"Handler_commit","0"
"Handler_delete","0"
"Handler_discover","0"
"Handler_prepare","0"
"Handler_read_first","0"
"Handler_read_key","1"
"Handler_read_last","0"
"Handler_read_next","0"
"Handler_read_prev","0"
"Handler_read_rnd","0"
"Handler_read_rnd_next","11"
"Handler_rollback","0"
"Handler_savepoint","0"
"Handler_savepoint_rollback","0"
"Handler_update","0"
"Handler_write","9"

select * from History where HistoryPlayer = 59161 and HistoryDate <= '2012-01-01' order by HistoryDate desc

SHOW SESSION STATUS LIKE 'Handler%';
"Variable_name","Value"
"Handler_commit","0"
"Handler_delete","0"
"Handler_discover","0"
"Handler_prepare","0"
"Handler_read_first","0"
"Handler_read_key","2"
"Handler_read_last","0"
"Handler_read_next","0"
"Handler_read_prev","71"
"Handler_read_rnd","0"
"Handler_read_rnd_next","20"
"Handler_rollback","0"
"Handler_savepoint","0"
"Handler_savepoint_rollback","0"
"Handler_update","0"
"Handler_write","17"

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Re: Select last row that is less than or equal to a date
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January 26, 2013 09:35AM


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