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Sample Code for Implementing Inner or Outer Join in esProc

Related computing can be: Inner join or outer join. The outer join can be further divided into left join, right join, and full join. With esProc, such kinds of related computing can be easily implemented. In the discussion below, we will introduce the join operations with some examples using the table emp and table sOr...

2014-09-03 15 0 0

Process Text Files with esProc

It is quite convenient to process data from text files with esProc, which provides many functions for processing text files: import various text files; process big text files; visit text files of hdfs; as well as general operations, such as, file moving, deleting and checking whether a file exists. The following will i...

2014-09-01 40 0 0

esProc’s Multilayer Parameters

esProc provides a large number of functions, many of which use many parameters. In order to clearly judge positions of these function parameters, and make writing and reading easier, esProc is specially equipped with multilayer separators of function parameters. 1. Separators of function parameters Colon (:), comma (,)...

2014-08-28 12 0 0

Binary File in esProc

In esProc, we often use two kinds of data file: The normal txt file and the binary file, of whichthe binary file adopts compressed encoding of low CUP consumption, meaning that a compressed binary file will take less space than an uncompressed txt file, andthe data reading efficiency will be higher. Thus, we can conclu...

2014-08-27 13 0 0

Aggregate Operations over Cursor in esProc

The data volume of big data table is usually quite huge, which makes it impossible to retrieve all data in the big data table. 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 the big data tab...

2014-08-26 17 0 0

Index Performance Comparison between Oracle and esProc

Data table indexing is a common method to accelerate query in Oracle. esProc also provides indexing function. With the actual measurements in the several examples below, we can compare their speed after indexing. The test is performed on data table T3 with 165 million records. The binary data file being saved in esProc...

2014-08-22 18 0 0

An Illustration of Processing Big Text Files with esProc Cursor

esProc can process big text files conveniently by providing cursor data object. The following example is to illustrate this. Let’s assume that there is a text file, sales.txt, with ten million sales records. Its main fields include SellerID, OrderDate and Amount. Now compute each salesman’s total Amount of big orders i...

2014-08-21 17 0 0

Alignment Grouping and Enumeration Grouping in esProc

Grouping records is often required during presenting and analyzing data in databases. Though records can group the designated fields by using Group By statement in SQL statements, this type of grouping serving the purpose of summaryis too simple to deal with some complex situations, like grouping according to designate...

2014-08-20 11 0 0

The Branch Statement in esProc

In branch statement, we need to check one or multiple conditions, execute different code according to the results or return different results. In esProc, the branch statement if/else has the following form: 1. if x … else … at the same line When condition x after if is true, execute the statement after it. Otherwise ex...

2014-08-19 11 0 0

esProc’s Foreign Key and Relationships Between Tables

In relational databases, foreign key is often used to handle relationships between tables. In esProc, this kind of corresponding relationships can also be represented by foreign key fields. 1. Computed columns and foreign key fields T.derive() function can be used in esProc to add computed columns to a table sequence, ...

2014-08-18 13 0 0

Application of Index Sequences in esProc

In databases, creating appropriate indexes for some tables can greatly increase query efficiency. Similarly, index sequences can be created for record sequences or table sequences in esProc to increase efficiency in querying data repeatedly. For example, we need to query food order Order_Foods.txtrepeatedly. Records o...

2014-08-15 13 0 0

Loop Code for esProc

With esProc, the code for loop is mainly implemented with for statement. The for statement will repeat the code block with for as the main cell. There are different formats of the for statements, as listed below: 1. The for loop Unconditional loop. The values of the main cell are, in turn, the count for the current loo...

2014-08-14 11 0 0

esProc’s Option Syntax

1.esProc’s function options Many functions in esProc can use function options with which the same function can have different work patterns. The basic format of function options is f@o(…) in which o is f function’s option. For example: We can use interval function to compute the days between two dates. In expressions ...

2014-08-13 12 0 0