The answers to your questions are complex, because they vary by InnoDB file format. Today, there are two formats, called Antelope and Barracuda.
The central tablespace file (ibdata1) is always in Antelope format. If you use file-per-table, you can make the individual files use Barracuda format by setting innodb_file_format=Barracuda
in my.cnf.
Basic points:
One 16KB page of InnoDB data must hold at least two rows of data. Plus each page has a header and a footer containing page checksums and log sequence number and so on. That's where you get your limit of a bit less than 8KB per row.
Fixed-size data types like INTEGER, DATE, FLOAT, CHAR are stored on this primary data page and count toward the row size limit.
Variable-sized data types like VARCHAR, TEXT, BLOB are stored on overflow pages, so they don't count fully toward the row size limit. In Antelope, up to 768 bytes of such columns are stored on the primary data page in addition to being stored on the overflow page. Barracuda supports a dynamic row format, so it may store only a 20-byte pointer on the primary data page.
Variable-size data types are also prefixed with 1 or more bytes to encode the length. And InnoDB row format also has an array of field offsets. So there's an internal structure more or less documented in their wiki. [EDIT] Dead link - here looks better now.
Barracuda also supports a ROW_FORMAT=COMPRESSED to gain further storage efficiency for overflow data.
I also have to comment that I've never seen a well-designed table exceed the row size limit. It's a strong "code smell" that you're violating the repeating groups condition of First Normal Form.
I have very bad news for you.
You should not have deleted the ibdata1 file. Here is why:
ibdata1 contains four type of information:
- table metadata
- MVCC data
- data pages (with innodb_file_per_table enabled)
- index pages (with innodb_file_per_table enabled)
Each InnoDB table created has a numercial id assigned to it via some auto increment metadata feature to each ibd file. That internal tablespace id (ITSID) is embedded in the .ibd file. That number is checked against the list of ITSIDs maintained, guess where, ... ibdata1.
I also have very good news for you along with some bad news.
It is possible to reconstruct ibdata1 to have the correct ITSIDs but it takes work to do it. While I personally have not done procedure alone, I assisted a client at my employer's web hosting to do this. We figured this out together but since the client hosed ibdata1, I let him do most of the work (30 InnoDB tables).
Anyway, here a past post I made in the DBA StackExchange. I answered another question whose root cause was the mixing up of ITSIDs.
To cut right to the chase, here is the article explaining what to do with reference to ITSID and how to massage ibdata1 into acknowledging the presence of the ITSID contained within the .ibd file.
I am sorry there is no quick-and-dirty method for recovering the .ibd file other than playing games with ITSIDs.
UPDATE 2011-10-17 06:19 EDT
Here is your original innodb configuration from your question:
innodb_file_per_table=1
innodb_flush_method=O_DIRECT
innodb_log_file_size=1G
innodb_buffer_pool_size=4G
innodb_data_file_path=ibdata1:10M:autoextend
innodb_buffer_pool_size = 384M
innodb_log_file_size=5M
innodb_lock_wait_timeout = 18000
Please notice that innodb_log_file_size is there twice. Look carefully...
innodb_file_per_table=1
innodb_flush_method=O_DIRECT
innodb_log_file_size=1G <----
innodb_buffer_pool_size=4G
innodb_data_file_path=ibdata1:10M:autoextend
innodb_buffer_pool_size = 384M
innodb_log_file_size=5M <----
innodb_lock_wait_timeout = 18000
The last setting of innodb_log_file_size takes precedence. MySQL expected to start up with the log files being 5M. Your ib_logfile0 and ib_logfile1 were 1G when you tried to start up mysqld. It saw a size conflict and took the path of least resistance, which was to disable InnoDB. That's why InnoDB was missing from show engines;
. Mystery solved !!!
UPDATE 2011-10-17 11:07 EDT
The error message was deceptive because innodb_log_file_size was smaller than the log files (ib_logfile0 and ib_logfile1), which were 1G at the time. What's interesting is this: Corruption was reported because the file was expected to be 5M and the files were bigger. If the situation were reversed and the innodb log files were smaller than the declared size in my.cnf you should get something like this in the error log:
110216 9:48:41 InnoDB: Initializing buffer pool, size = 128.0M
110216 9:48:41 InnoDB: Completed initialization of buffer pool
InnoDB: Error: log file ./ib_logfile0 is of different size 0 5242880 bytes
InnoDB: than specified in the .cnf file 0 33554432 bytes!
110216 9:48:41 [ERROR] Plugin 'InnoDB' init function returned error.
110216 9:48:41 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
In this example, the log files were already existing as 5M and the setting for innodb_log_file_size was bigger (in this case, 32M).
For this particular question, I blame MySQL (eh Oracle [still hate saying it]) for the inconsistent error message protocol.
Best Answer
Ok I feel really stupid now... Problem had nothing to do with MySQL Server settings etc. Problem was that in my service (that is communicating with MySQL) I'm using MySqlCommand Object (Service is coded using VB NET). This MySqlCommand object has a parameter CommandTimeout and its default value is 30. So that was the reason why executions longer than 30s caused timeout that throws fatal error.. So now I'm setting this parameter large enough in my VB NET code before executing command and everything is working as planned!