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From GitBox <...@apache.org>
Subject [GitHub] [madlib] dadanielniel opened a new pull request #523: Prevent an "integer out of range" exception in linear regression train
Date Tue, 27 Oct 2020 10:10:42 GMT

dadanielniel opened a new pull request #523:
URL: https://github.com/apache/madlib/pull/523


   ### Module name: Linear-Regression
   
   ### JIRA: MADlib-1460
   
   ### Description:
   
   Linear regression training results in 2 output tables (**neither are optional**): 
   
   The **primary** output table, that includes the computed coefficients.
   A **summary** output table, that contains a single line.
   
   #### Scenario
   
   Running the linear regression training in postgresql on an input table which has **more
than 2^31 records** within it (even if a grouping column is specified), fails due to an
"**integer out of range**" exception.
   
   #### Source
   
   **The summary table** has a column that stores **the total number of records** involved
in the computation. The column's data type is a **singed integer**. However, the total number
of records is computed as a **BIGINT**. Therefore, when the total number of records in the
input table is beyond the range of a signed integer (i.e., 2^31), an "integer out of range"
exception is thrown.
   
   ### Solution
   
   A simple solution is to change the data type of the column from a **signed integer** into
a **BIGINT**. 
   
   ### Test
   
   We have executed the linear regression training function with and without the suggested
modification on an input table having between 2^31-2^32 records. Without the modification,
an integer out of range exception was thrown. After modifying the code as suggested, it worked
perfectly. 
   


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