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I know there is one issue in MySQL with concurrent SELECT and INSERT. However, my question is if I open up two connections with MySQL and keep loading data using both of them, does MySQL takes data concurrently or waits for one to finish before loading another?
I’d like to know how MySQL behaves in both cases. Like when I am trying to load data in the same table or different tables concurrently when opening separate connections.
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You may use one buffer table (Temporary table) in the sense of concurrency control with the help of LOCK'ing mechanism of MySQL. So while one request's to the server on the priority base you can set remains request as in queue or in the sense restrict the table.
It can be set to use up to 64. Each thread handles up to 256 pending I/O requests.
The INSERT statement in MySQL also supports the use of VALUES syntax to insert multiple rows as a bulk insert statement. To do this, include multiple lists of column values, each enclosed within parentheses and separated by commas.
If both the column list and the VALUES list are empty, INSERT creates a row with each column set to its default value: INSERT INTO tbl_name () VALUES(); If strict mode is not enabled, MySQL uses the implicit default value for any column that has no explicitly defined default.
If you will create a new connection to the database and perform inserts from both the links, then from the database's perspective, it will still be sequential.
The documentation of Concurrent Inserts on the MySQL's documentation page says:
If there are multiple INSERT statements, they are queued and performed in sequence, concurrently with the SELECT statements.
Mind that there is no control over the order in which two concurrent inserts will take place. The order in this concurrency is at the mercy of a lot of different factors. To ensure order, by default you will have to sacrifice concurrency.
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