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Mike is currently working as a senior LAMP architect for a San Francisco start-! !up. With over 30-years of exeperience in the programming field, his only comment is "I should know better by now." Micheal is a DZone MVB and is not an employee of DZone and has posted 12 posts at DZone. You can read more from them at their website. View Full User Profile

MongoCursorException: E11000 Duplicate Key Error Index

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So I’m working on a project where I’m taking a csv file that contains a little more than 100 columns of data by 10,000 rows.  (It’s a sample db file — the final file will be about 200,000,000 rows…) and writing a PHP script to process the csv file into structures that can be inserted as mongodb collections.

I’m rocking along and all is working well for initial tests of the algorithm (header + first row of actual data) but when I turn-on processing for the other 9,999 rows, all I get stored into mongo is the first row of data.

I add an echo statement after the insert and I see 10,000 names scroll across my terminal.  So the problem isn’t that I’m not getting the data, it’s that the data isn’t being stored into Mongo.  I try turning on safe writes on my $mongo->insert() function and *bam*, error message:

PHP Fatal error:  Uncaught exception ‘MongoCursorException’ with message ‘E11000 duplicate key error index: insite.testdata.$_id_  dup key: { : ObjectId(’4d25fd9a7e03972618000000′) }’ in /htdocs/framework/parseCSV.php:449
Stack trace:
#0 /htdocs/framework/parseCSV.php(449): MongoCollection->insert(Object(mongorriffic), Array)
#1 {main}
thrown in /htdocs/framework/parseCSV.php on line 449

My code looks like this:

if (($handle = fopen($argv[1], "r")) !== FALSE) {
while (($data = fgetcsv($handle, 0, ",")) !== FALSE) {
if (!$row) {
// use the csv headers to instantiate the new mongo object
$objMongo = new mongorriffic($data);
} else {
// parse the data into the existing structure

I’m calling my internal method (storeDate()) but I’m not creating, populating or resetting an “_id” field value because mongodb is supposed to automagically handle that for me.  What’s actually happening is that mongodb  is creating a valid “_id” value for the first record, but since my method does nothing to manipulate the field, the value persists through iterations of the data. I fix this by adding the following line of code after I invoke the insert method:


I re-run my script and *success*!   10,000 records are stored in less than 6-seconds using 4 collections.  BTW,  am *loving* Mongodb….

Published at DZone with permission of Micheal Shallop, author and DZone MVB. (source)

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