The default values in the field would most likely be retrieved from a database or operational system, using the UPC symbol as the key value.

字段中的默认值很可能是通过使用upc符号作为键值从一个数据库或运营系统中检索到的。

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Then when a value is set, the key is removed from the database and a new record is added with the updated value.

在设置一个值后，键就从数据库中移除掉，并添加一条具有更新过的值的新记录。

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It will simply return a value of 0 as the key to the trade order without changing the database.

它只是返回一个值0作为交易订单的键，而不会更改数据库。

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"Schooner's MySQL and NoSQL solutions combined with the LSI WarpDrive card provide industry-leading performance for database and key-value stores, delivering over 9x performance throughput increase relative to hard drive configurations and over 3x performance throughput increase relative to alternative PCIe flash-based solutions, " said Dr. John Busch, founder and CTO, Schooner Information Technologies.

ENGADGET: LSI's WarpDrive SSD is a steal at $11,500

In a document database, such as CouchDB or MongoDB, documents are key-value pairs.

FORBES: What You Need to Know About NoSQL Databases