With this type of lock, concurrent applications can read from or write to the locked table.
有了这一类型的锁，并发应用程序就可以读或写已锁定的表。
When a table holds a Z lock, no concurrent application can read or update data in that table.
当表持有z锁时，任何并发应用程序都不能读取和更新该表中的数据。
When a table holds an IX lock, the lock owner and concurrent applications can read and update data in that table.
当表持有IX锁时，锁拥有者和并发应用程序可以读和更新该表中的数据。
The s lock allows concurrent applications that use read-only queries to access the target table, but applications attempting to write data to the table are prevented from doing so.
s锁允许使用只读查询的并发应用程序访问目标表，但是防止应用程序写数据到表中。
So to find the row that satisfies the predicate in the select statement, the optimizer has to lock, read in, and compare all the rows in the main table with the value supplied in the predicate.
因此要找到满足select语句中谓词的行，这个优化器必须将主表中的所有行上锁、读取它们的值并与谓词中提供的值进行比较。
So to find the row that satisfies the predicate in the select statement, the optimizer has to lock, read in, and compare all the rows in the main table with the value supplied in the predicate.
因此要找到满足select语句中谓词的行，这个优化器必须将主表中的所有行上锁、读取它们的值并与谓词中提供的值进行比较。
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