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What is system lock in MySQL?
The mysql_load() function calls the open_and_lock_tables() function to lock the table mentioned in the LOAD DATA statement. MySQL obtains an exclusive lock on the table so that it can very quickly load data into the table.
What does system lock mean?
System lock makes it so it’s safe to leave your computer alone but makes it so you don’t have to shut down.
What is sending data state in MySQL?
Sending data. The thread is reading and processing rows for a SELECT statement, and sending data to the client. Because operations occurring during this state tend to perform large amounts of disk access (reads), it is often the longest-running state over the lifetime of a given query. Sending to client.
To lock your phone without a power button, try double-tapping your screen. Many modern Android devices have a double-tap to unlock and lock feature available.
What does system lock mean in MySQL profiling?
The CONCURRENT option only affects MyISAM tables, if you are loading into an InnoDB table it does not permit concurrent access. The reason why System lock took so long is that the actual data load was lumped into the timing for that step.
Why does system lock take so long in MySQL?
The reason why System lock took so long is that the actual data load was lumped into the timing for that step. The profiler works by measuring time between fenceposts, that is the entry time is logged for each instrumented user function.
What does the system lock mean in SQL thread state in replication?
What does the system lock means in sql thread state in replication. The mysql_load() function calls the open_and_lock_tables() function to lock the table mentioned in the LOAD DATA statement. MySQL obtains an exclusive lock on the table so that it can very quickly load data into the table.
What does ” system lock ” mean in InnoDB profiling?
For SHOW PROFILE, this state means the thread is requesting the lock (not waiting for it). This should not be surprising since InnoDB does row-level locking. In addition, the gen_clust_index (a.k.a. Clustered Index) will experience Shared and Exclusive Locks on the Primary Key at some point.