Github user karup1990 commented on the pull request:
https://github.com/apache/incubator-zeppelin/pull/695#issuecomment-179935889
When SparkSqlinterpreter returns the result , ZeppelinContext constructs a
String out of it for displaying on UI.
The logic to construct result string uses String Class for each column
value in each row.
If result has x rows and each row has y columns, it creates x * y String
objects for constructing the result string.
For large values of x and y, the number of String objects created is
enormous and is time consuming.
Instead we could use StringBuilder, which will reduce number of objects
created and will be faster.
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