key-value

I know a map is a data structure that maps keys to values. Isn't a dictionary the same? What is the difference between a map and a dictionary 1 ? 1. I am not asking for how they are defined in language X or Y (which seems to be what generally people are asking here on SO), I want to know what is their difference in theory. Two terms for the same thing: "Map" is used by Java, C++ "Dictionary" is used by .Net, Python "Associative array" is used by PHP "Map" is the correct mathematical term, but it is avoided because it has a separate meaning in functional programming . Some languages use still

I have following code, where I used HashMap (using two parallel arrays) for storing key-value pairs (key can have multiple values). Now, I have to store and load it for future use that's why I store and load it by using File Channel. Issue with this code is: I can store nearly 120 millions of key-value pairs in my 8 GB server (actually, I can allocate nearly 5 gb out of 8 gb for my JVM, and those two parallel arrays takes nearly 2.5 gb, other memory are used for various processing of my code). But, I have to store nearly 600/700 millions of key-value pairs. Can anybdoy help me how to modify

I need to store few items and its properties in form of a key value pairs in the database (mySQL). I am planning to do it as following. I'll use two tables items and item_properties . items itemId | itemName ------------------- 1923 | AC 1235 | Fridge 8273 | Heater item_properties itemId | property | value -------------------------------- 1923 | effect | cooling 1923 | consumption | efficient 1923 | type | split 1235 | effect | cooling 1235 | volume | 20 liters 8273 | effect | heating 8273 | consumption | efficient 8273 | heatMethod | coil Now, if I have to select items whose 'effect' is

I'm interperting a json string into a variable using jquery's parseJSON() function. The problem is, it's turning my data into an object instead of a 2d array. Eg, myData = $.parse(JSON(data)); myData.name// = "Bob" The problem is, "name" is not supposed to be a key (assuming that is the correct term). Instead, it should be: myData[0] // = "name" myData[1] // = "Bob" How would I convert this? Or is there a different method than using a for loop to walk through the index of an array (but still be able to access both key and value as a string, as you would in a 2d array). EDIT: This is some json

I found that they have one key and multiple values which is unique. The multimap stores pairs of (key, value) where both key and value can appear several times. The map<key, set<value>> will only store each value once for a specific key. To do that, it will have to be able to compare the values, not just the keys. It depends on your application if the values that compare equal are equivalent, or if you wish to store them separately anyway. Perhaps they contain fields that are different but do not take part in the comparison for the set. A std::map is an associative container, that allows you

I have been looking for cloud computing / storage solutions for a long time (inspired by the Google Bigtable). But I can't find a easy-to-use, business-ready solution. I'm searching a simple, fault tolerant, distributed Key=>Value DB like SimpleDB from Amazon. I've seen things like: The CouchDB Project : Simple and distributed, fault-tolerant Database. But it understands only JSON. No XML connectors etc. Eucalyptus : Nice Amazon EC2 interfaces. Open Standards & XML. But less distributed and less fault-tolerant? There are also a lot of open tickets with XEN/VMWare issues. Cloudstore / Kosmosfs