STATUS
STATUS解釋
Handler_read_first
The number of times the first entry was read from an index.
If ``this value is high, it suggests that the server is doing a lot of full index scans;
for example, SELECT col1 FROM foo, assuming that col1 is indexed.
索引中第一條被讀的次數。如果較高，它建議服務器正執行大量全索引掃描；例如，SELECT col1 FROM foo，假定col1有索引。
Handler_read_key
The number of requests to read a row based on a key.
If ``this value is high, it is a good indication that your tables are properly indexed ``for your queries.
根據鍵讀一行的請求數。如果較高，說明查詢和表的索引正確。
Handler_read_next
The number of requests to read the next row in key order.
This value is incremented ``if you are querying an index column with a range constraint or ``if you are doing an index scan.
按照鍵順序讀下一行的請求數。如果你用范圍約束或如果執行索引掃描來查詢索引列，該值增加。
Handler_read_prev
The number of requests to read the previous row in key order.
This read method is mainly used to optimize ORDER BY ... DESC.
按照鍵順序讀前一行的請求數。該讀方法主要用于優化ORDER BY ... DESC。
Handler_read_rnd
The number of requests to read a row based on a fixed position.
This value is high ``if you are doing a lot of queries that require sorting of the result.
You probably have a lot of queries that require MySQL to scan entire tables or you have joins that don't use keys properly.
根據固定位置讀一行的請求數。如果你正執行大量查詢并需要對結果進行排序該值較高。你可能使用了大量需要MySQL掃描整個表的查詢或你的連接沒有正確使用鍵。
Handler_read_rnd_next
The number of requests to read the next row in the data file.
This value is high ``if you are doing a lot of table scans.
Generally ``this suggests that your tables are not properly indexed or that your queries are not written to take advantage of the indexes you have.
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在數據文件中讀下一行的請求數。如果你正進行大量的表掃描，該值較高。通常說明你的表索引不正確或寫入的查詢沒有利用索引。
從第二條執行計劃可以看出，shotel表只用到idx_supplier_id并沒有用到shotel的主鍵，handler_read_rev數值很大，猜測應該是掃描得到結果，所以速度很慢。
