Here, we use esProc to analyze stock bullish trend. There is a variety of specific algorithms, from which, one will be illustrated the whole process in detail. Other cases can be solved in the similar codes. Specific requirements are:
Among the stocks which have kept going up for N days, what is the proportion of those...
2014-09-05 841 0
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Program development in Java involves cross-database relational operations. The following example will illustrate Java’s method of handling these operations. sales table is in db2 database, employee table is in mysqldatabase. The task is to joinsales withemployee through sellerid of sales table and eid of employee table...
2014-09-04 1455 0
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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...
2014-09-03 839 0
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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 1185 0
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Link relative ratio refers to comparison between the current data and data of the previous period. The interval is usually one month. For example, divide sales amount of April by that of March, and you get the link relative ratio of April. Hour, day, week and quarter can also be used as the time interval. Year-on-year ...
2014-08-29 820 0
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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 (,)...
2014-08-28 772 0
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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...
2014-08-27 873 0
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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...
2014-08-26 792 0
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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...
2014-08-22 828 0
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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...
2014-08-21 771 0
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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...
2014-08-20 753 0
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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...
2014-08-19 725 0
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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, ...
2014-08-18 779 0
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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...
2014-08-15 776 0
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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...
2014-08-14 723 0
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