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    <p>I have written PHP scripts to bulk-load the data published by Stack Overflow data dump. I import millions of rows and it doesn't take that long. </p> <p>Here are some tips:</p> <ul> <li><p><strong>Don't rely on autocommit.</strong> The overhead of starting and committing a transaction for every row is enormous. Use explicit transactions, and commit after every 1000 rows (or more).</p></li> <li><p><strong>Use prepared statements.</strong> Since you are basically doing the same inserts thousands of times, you can prepare each insert before you start looping, and then execute during the loop, passing values as parameters. I don't know how to do this with CodeIgniter's database library, you'll have to figure it out.</p></li> <li><p><strong>Tune MySQL for import.</strong> Increase cache buffers and so on. See <a href="http://dev.mysql.com/doc/refman/5.1/en/insert-speed.html" rel="noreferrer">Speed of INSERT Statements</a> for more information.</p></li> <li><p><strong>Use LOAD DATA INFILE.</strong> If possible. It's literally 20x faster than using INSERT to load data row by row. I understand if you can't because you need to get the last insert id and so on. But in most cases, even if you read the CSV file, rearrange it and write it out to multiple temp CSV files, the data load is still faster than using INSERT.</p></li> <li><p><strong>Do it offline.</strong> Don't run long-running tasks during a web request. The time limit of a PHP request will terminate the job, if not today then next Tuesday when the job is 10% longer. Instead, make the web request queue the job, and then return control to the user. You should run the data import as a server process, and periodically allow the user to glimpse the rate of progress. For instance, a cheap way to do this is for your import script to output "." to a temp file, and then the user can request to view the temp file and keep reloading in their browser. If you want to get fancy, do something with Ajax.</p></li> </ul>
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    1. COOkay, thanks for these tips. I read up on the Speed of INSERT Statements and now I know what you mean by the autocommit... What I think I will do is run it on an engine (this engine is already set up on the system, I just didn't know how to work it) which will load, say, 100 rows every few minutes, and instead of doing an auto-insert every line it'll generate a long query to load all of them in one insert, each time the script loads. If this works better speed-wise, too, I can probably up it to around 400-500 without causing much trouble. I'll work on it more and see how it goes. Thanks!
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    2. COAlright, progress update. I've finished updating the script and getting everything re-written, with all bugs fixed. I rewrote the script to not have such a long switch statement (mentioned below), but also to simply grab data and create a series of arrays that holds all the field data to be inserted, and I've also added checks to calculate the Inserted ID (either checking the max id or returning the current row number). After reaching the end of the file, the insert statements are created and run. 1,200 rows takes a few seconds. I'm going to try something longer, but it works MUCH better.
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