In esProc, constants can be directly stored in cells and be referenced in expressions. For the basic usage of constants, please refer to esProc Getting Started: Constants. Actually, when a constant stored in a cell is referenced, it means the value of the cell is used as a variable. The parameters and variables in esPr...
2015-10-28 325 0
esProc External Memory Computing: Merge and Join Cursor Data discussed how to have several big data tables joined and retrieve data from them. But we notice that, though it’s convenient to handle big data with the cursor, there’s the restriction of one-way retrieval from front to back. Hence data sorting becomes the pr...
2015-10-16 386 0
Through esProc Parallel Computing: Data Redundancy, we know that for cluster computation data files can be stored in separate servers, with data redundancy solution adopted. Thus the parallel program will find the appropriate node for a subtask according to where the needed files are stored. The fact is, during real wo...
2015-10-13 561 0
esProc Parallel Computing: Cluster Computing explains how to use cluster computing to process massive data or handle tasks involving a large amount of computation.
1. The problem with parallel computing
Parallel computing requires that the dfx file to be invoked be stored in all nodes, and that the data files the subta...
2015-10-09 642 0
It is convenient to establish and close a connection to MongoDB in esProc , as well as to call the database to query and count the data, perform distinct and aggregate operations.
1. Preparation for connecting to MongoDB
The MongoDB Java driver (like mongo-java-driver-2.12.2.jar), which esProc does’nt provide, should b...
2015-09-18 385 0
Parallel computing allows executing a computation on big data by distributing it to nodes. If the data distributed to each node is still in large volume, it can be returned from the node with the remote cursor. We’ll now learn the usage of the remote cursor as well as its features.
1. The usage
The servers the remote c...
2015-09-11 409 0
Two kinds of data file – the normal text file and the binary file – are most used in esProc, of which the binary file adopts compressed encoding of low CPU consumption, meaning that it takes less space than an uncompressed text file, and the data reading efficiency will be higher. Thus, we can conclude that the b...
2015-09-10 469 0
Indexed Sequences in esProc discusses how to create an index of a table sequence or a text file in esProc to greatly speed up the query on desired fields. But how to deal with a data-intensive file whose index table cannot be loaded into the memory? Here let’s look at how to increase the speed of big data handling by c...
2015-09-09 369 0
In esProc Parallel Computing: Multithreading, we learned how to increase efficiency through executing multithreaded computation. But besides using fork in the cellset code to achieve the multithreading type of parallel processing, esProc also builds the approach of parallel processing into some functions. Let’s find ou...
2015-07-31 429 0
The data volume of the big data table is usually quite huge, which makes it impossible to retrieve all data from the big data table at once. In view of this, the data processing over big data table is usually to serve two purposes: With cs.fetch(), retrieve partial data each time or group & aggregate the data in th...
2015-07-29 440 0
Cluster computing can be used in esProc for performing complicated analytic and processing tasks. A cluster system consists of multiple parallel servers running on independent computers in a network. Every single computer in this network can send a parallel computing request to the cluster.
A cluster system enhances co...
2015-07-28 597 0
During data computing based on the table sequence, we can combine data from multiple table sequences together for use in the analysis and computation. For instance, use A.merge() to combine records of multiple table sequences in a certain order, or A.conj() to union them in order into a grand table, or JOIN functions, ...
2015-07-28 435 0
In esProc Charts: The Basics, esProc Charts: Coordinate Axes and Coordinate Transformation, as well as other documents explaining using chart elements in esProc charts, we discussed the method for plotting charts in esProc. To display charts on web, however, hyperlinks are often required. Here we’ll see how to design ...
2015-06-24 383 0
The series of articles on esProc charts discussed how to use chart elements in plotting algorithms to make charts. Besides writing plotting algorithms, we can use a number of built-in ready-made graphs to quickly plot common styles of charts.
There are four types of ready-made graphs (Column graph, Line graph, Pie grap...
2015-06-16 550 0
In esProc, it is common to add text to various charts. The text is plotted and positioned with the text element, and has its own style compared with text working with other chart elements (though the latter’s properties can be adjusted in a similar way).
The text element has a relatively simple functi...
2015-06-03 555 0