Does MYSQL truncate a table when the tables size limit is reached?

I have been pouring over the MYSQL documentation trying to determine if my script or MYSQL itself is causing a truncation of a large table. The basic behavior I am seeing:

• A PHP script is kicked off from the browser to select rows from a MSSQL table and immediately insert them into a local MySQL database table.
• After determining the number of rows in MSSQL, my script breaks down the select into chunks to avoid any out of memory issues.
• The script then truncates the local table and starts to import the data by iterating over the chunks
• Following the data in MySQL directly, I see the table close in on ~20开发者_JAVA技巧0,000 rows and then suddenly the table truncates and the count starts over
• I would think that I would see some errors about the table being full and I didn't think MySQL would truncate the table if the table limit was reached.

Can anyone confirm whether or not MySQL would truncate a table automatically if the table limit is reached or a setting to check to turn off such behavior?

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No MySQL sets no hard limits on the size of the table, but there are some limits...

Explicit table size
You can set the max table size with

ALTER TABLE tbl_name MAX_ROWS=200000

You can see the current settings for table size with

SHOW TABLE STATUS FROM db_name LIKE 'tbl_name';

See: http://dev.mysql.com/doc/refman/5.0/en/full-table.html

Note that MAX_ROWS is:

The maximum number of rows you plan to store in the table. This is not a hard limit, but rather a hint to the storage engine that the table must be able to store at least this many rows.

Filesystem limits
MySQL 5.x has a default tablesize of 256TB, but if your filesystem does not allow files > 4GB, that might be a limit that can cause this behaviour as well.

Memory limits
If you're using the memory (heap) engine, your table size is determined by the max_heap_table_size system variable.

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I don't think MySQL is truncating your data, I'v worked with tables with 500,000 rows or more and I had no problems at all. So, I think you better watch out your PHP Script or at least the PHP configuration, all the timeouts setting and size of the scripts that PHP can handle.

• max_execution_time
• max_input_time
• memory_limit

I hope this could help you.