Pyspark Rename Column After Join

how to rename all the column of the dataframe at once; how to rename the specific column of our choice by column name. columns = new_column_name_list However, the same doesn't work in pyspark dataframes created using sqlContext. Pivot queries involve transposing rows into columns (pivot) or columns into rows (unpivot) to generate results in crosstab format. Here’s my everyday reference when working on Hadoop and Spark. Creating New Tables. As there are multiple columns in my report and some of which contains long texts without any space or separator. In this tutorial, you will learn how to rename the columns of a data frame in R. maxFailures. PySpark DataFrame filtering using a UDF and Regex. The only time the position is an issue is when you use SELECT *. The word COLUMN is optional and can be omitted, except for RENAME COLUMN (to distinguish a column-renaming operation from the RENAME table-renaming operation). on - a string for the join column name, a list of column names, a join expression (Column), or a list of Columns. the first column in the data frame is mapped to the first column in the table, regardless of column name). Display a delimited file in the Linux terminal so that each delimited item is displayed within its own column. In R, there are multiple ways to select or drop column. In this case, you’re going to supply the path /usr/local/spark to init () because you’re certain that this is the path where you installed Spark. Configure PySpark driver to use Jupyter Notebook: running pyspark will automatically open a Jupyter Notebook. Renaming DataFrame Columns after Pivot in PySpark. withColumn() method. the column is used often when multiple tables are joined together 7. We will show two ways of appending the new column, the first one being the naïve way and the second one the Spark way. After you’re comfortable with moving around the hierarchy of your hard drive in UNIX, it’s a cinch to copy, move, and rename files and folders. To rename objects, columns, and indexes, requires ALTER permission on the object. how - str, default 'inner'. r m x p toggle line displays. Note that the ^ and $ surrounding alpha are there to ensure that the entire string matches. DB Mission¶. In this tutorial we will learn how to rename the column of dataframe in pandas. the value of the column is seldom NULL 4. [SPARK-16690][TEST] rename SQLTestUtils. You can rearrange a DataFrame object by declaring a list of columns and using it as a key. Recall the example described in Part 1, which performs a wordcount on the documents stored under folder /user/dev/gutenberg on HDFS. Apache Phoenix takes your SQL query, compiles it into a series of HBase scans, and orchestrates the running of those scans to produce regular JDBC result sets. Quickly see all your bookmarks, double-click to jump to any of them or click to rename. If on is a string or a list of strings indicating the name of the join column(s), the column(s) must exist on both sides, and this performs an equi-join. sql import DataFrame, Row: from functools import reduce. SQL alter table add column guide: find SQL add column syntax & SQL alter table add column examples. column_name = table2. This is a known bug in Microsoft Office Excel 2007. apply the same logic for Join and answer this question not have the same order of columns, it is better to. Rename Column » The Alter Column statement can modify the data type and the Nullable attribute of a column. Pyspark Joins by Example This entry was posted in Python Spark on January 27, 2018 by Will Summary: Pyspark DataFrames have a join method which takes three parameters: DataFrame on the right side of the join, Which fields are being joined on, and what type of join (inner, outer, left_outer, right_outer, leftsemi). In a natural join, all the. For example, if data in a column could be an int or a string, using a project:string action produces a column in the resulting DynamicFrame where all the int values have been converted to strings. Created with Highcharts 6. In the query results so far, I’ve allowed the DBMS to use default values for column headings. January 13, 2010 02:47PM. Code Example: Data Preparation Using ResolveChoice, Lambda, and ApplyMapping The dataset that is used in this example consists of Medicare Provider payment data downloaded from two Data. The common function to use is newvariable - oldvariable. Every row in the left table is returned in the result set, and if the join condition is not met, then NULL values are used to fill in the columns from the. Click on the plus sign next to function, you wish to rename. php on line 143 Deprecated: Function create. The Pandas Python library is an extremely powerful tool for graphing, plotting, and data analysis. coz i have a Table named 'studentAttendance' having columns like d1,d2,d3,d4d30 and this columns have values like 'P','A','L','C' for daily attendance. If you want to add a column at a specified position, Rename the position column to the new column name For Ex: (OLD_COLUMN_NAME-Hiredate) ALTER TABLE EMP RENAME COLUMN OLD_COLUMN_NAME TO TEMP_HIREDATE;. First, specify the table where you want to update after the UPDATE clause. dataframe globs. Exercise 11c: Finally, let’s compare the value of items in this file that are in location 05 with the calculations that you obtained in exercise 8. For more information on the RENAME= data set option, see the section on SAS data set options in SAS Language Reference: Dictionary. The only time the position is an issue is when you use SELECT *. SQL: ALTER TABLE Statement. Also had to spend a lot of time trying to work out the syntax for SparkR and SparklyR for parsing. The difference lies in how the data is combined. The index will be named after the table and the column name(s), unless you pass :name as an option. They are extracted from open source Python projects. You aren't stuck with the same fields you began with when you first created an Access query—it's possible to rename your queries without going back to square one. spark pyspark dataframes join. This can be replicated with: bin/spark-submit bug. Combine DataFrame objects with overlapping columns and return only those that are shared by passing inner to the join keyword argument. Learn the basics of Pyspark SQL joins as your first foray. Plz do suggest a right way to do it. By default, after executing a SELECT statement, the column heading(s) displayed in the result set is the name of the column in the table. def when (self, condition, value): """ Evaluates a list of conditions and returns one of multiple possible result expressions. Endnotes In this article, I have introduced you to some of the most common operations on DataFrame in Apache Spark. After you parse the logs plotting and analysis is a piece of cake! This is definitely worth a try! Watch this space!! Also see 1. Otherwise, it returns as string. It does this using make. The third example shows how to again change the name of a column using the column name to identify which column to apply the name to. 1 to the 2nd data frame column names. This is one of the 100+ free recipes of the IPython Cookbook, Second Edition, by Cyrille Rossant, a guide to numerical computing and data science in the Jupyter Notebook. However, you can use the RENAME= data set option with the CREATE TABLE or SELECT statement. To add a column called email to the contacts table created in Create a basic MySQL table with a datatype of VARCHAR(80), use the following SQL statement: ALTER TABLE contacts ADD email VARCHAR(60); This first statement will add the email column to the end of the table. The only time the position is an issue is when you use SELECT *. DataGrid columns. Rename the new copy of the dimension to the desired name. Variables are always added horizontally in a data frame. concat(*cols) Concatenates multiple input columns together into a single column. I could not replicate this in scala code from the shell, just python. It's time to expand table columns today, and get you acquainted with the ninth pitfall, which can be quite risky, as you'll soon find out. Plz do suggest a right way to do it. And not all the column names need to be changed. column_name = table_2. PySpark is a Spark Python API that exposes the Spark programming model to Python - With it, you can speed up analytic applications. To do this in SQL, we specify that we want to change the structure of the table using the ALTER TABLE command, followed by a command that tells the relational database that we want to rename the column. Alter a Table. [phone] ADD inactive_date DATETIME NULL GO Alter column. This is correct only for joins on unique columns and wrong if columns in both tables are not unique. This is very easily accomplished with Pandas dataframes: from pyspark. The different arguments to merge() allow you to perform natural join, left join, right join, and full outer join in pandas. Suppose there is a situation where you rename a column in the middle of your development. Columns of same date-time are stored together as rows in Parquet format, so as to offer better storage, compression and data retrieval. frm file with the changed dictionary information. That will prevent the column header from becoming to the date’s value and then you can manually rename the column to “Date”. The column-name join is like a natural join, but it's more flexible. Here’s an example of adding a created_at timestamp column to your users table in PostgreSQL. j k next/prev highlighted chunk. spark pyspark dataframes join. A pseudo-column is an Oracle assigned value (pseudo-field) used in the same context as an Oracle Database column, but not stored on disk. Variables are always added horizontally in a data frame. Employ aliases to assign new names to items in a query. For example for the SQL query in Figure 4. # all columns after. The names of the key column(s) must be the same in each table. The problem is that these tables have common columns. LEFT JOIN, RIGHT JOIN The default SQL join is an Inner Join, meaning that only rows that match across both tables are included LEFT JOIN and RIGHT JOIN in Proc SQL always operate on exactly two tables, and the order the tables are listed is very significant. new column name: table1_xyz. “A Spark and Hadoop cheat sheet of an impatient Data Scientist” is published by rbahaguejr. It’s also possible to use R base functions, but they require more typing. In this example, we merge the same columns as earlier (OrderID and CustomerID), separated by a space. When adding columns you can specify all the same settings available when creating a table. how to rename all the column of the dataframe at once; how to rename the specific column of our choice by column name. When performing data analysis, we often need to "reshape" our data from wide format to long format. Suppose I have tables a (with column a1) and b (with columns b1 and b2) and I perform a left outer join. Highcharts Demos › With data labels. Moving a process from background to foreground Monday, December 31, 2012 shell-script , shell-scripting 0 Comments In unix, if we run a process(a shell script). In our company we have a data warehouse build to support the PowerBI tabular model with the data. With time business requirements change as well. The UPDATE statement is used to modify data in a database table. The original creator or owner of this folder will automatically have the Admin permissions required to rename it. Columns of same date-time are stored together as rows in Parquet format, so as to offer better storage, compression and data retrieval. Data Engineers Will Hate You - One Weird Trick to Fix Your Pyspark Schemas May 22 nd , 2016 9:39 pm I will share with you a snippet that took out a lot of misery from my dealing with pyspark dataframes. Rename Multiple pandas Dataframe Column Names. That is, you can change a column heading by using a column alias. I usually use Jupyter to do this which is very easy to ensure the computation consistency step by step. If I import a table in Excel PowerQuery, what functions and syntax do I use to reference another table for the names of the different columns? 0 0. How to Index Foreign Key Columns in SQL Server September 5, 2017 by Ahmad Yaseen Before going through the main concern of this article, indexing the foreign key columns, let’s take a small trip back to review the SQL Server Indexes and Foreign Key concepts. other – Right side of the join; on – a string for the join column name, a list of column names, a join expression (Column), or a list of Columns. Hi, I need to add new column into an existing table in hana system. At the end of the PySpark tutorial, you will learn to use spark python together to perform basic data analysis operations. I know that the PySpark documentation can sometimes be a little bit confusing. which I am not covering here. It converts MLlib Vectors into rows of scipy. This is just a pandas programming note that explains how to plot in a fast way different categories contained in a groupby on multiple columns, generating a two level MultiIndex. You can vote up the examples you like or vote down the ones you don't like. You aren't stuck with the same fields you began with when you first created an Access query—it's possible to rename your queries without going back to square one. SQL RENAME TABLE syntax is used to change the name of a table. Code Example: Data Preparation Using ResolveChoice, Lambda, and ApplyMapping The dataset that is used in this example consists of Medicare Provider payment data downloaded from two Data. Is there a better method to join two dataframes and not have a duplicated column? pyspark dataframes join column. Use either mapper and axis to specify the axis to target with mapper, or index and columns. Sometimes, we choose non-meaningful name for the table. However before doing so, let us understand a fundamental concept in Spark - RDD. The ALTER TABLE statement changes table attributes (column definitions and constraints) in a table that was previously created. A bit of annoyance in Spark 2. In-Memory computation and Parallel-Processing are some of the major reasons that Apache Spark has become very popular in the big data industry to deal with data products at large scale and perform faster analysis. The -Newname parameter does not accept wildcards, but you can use a -replace expression to calculate the new name. Mary Ann Richardson shows how. The syntax of withColumn() is provided below. This blog post introduces the Pandas UDFs (a. We will learn. login' column before removing all the columns that start with 'assignee' together. With FIRST or AFTER, can reorder columns. I have 3 tables (mysql db) on which I want to do an inner join. It takes a nested list of old and new column names as its second argument. You aren't stuck with the same fields you began with when you first created an Access query—it's possible to rename your queries without going back to square one. Learn of SQL alter table add column statement here!. In the Group By grid column, select the appropriate aggregate function, such as: Sum, Avg, Min, Max, Count. Has more capability than MODIFY, but at the expense of convenience for some operations. RenameColumns. Add a column, drop a column, rename a column, or change a column's data type. Use either mapper and axis to specify the axis to target with mapper, or index and columns. Pandas drop function allows you to drop/remove one or more columns from a dataframe. If on is a string or a list of strings indicating the name of the join column(s), the column(s) must exist on both sides, and this performs an equi-join. This add the column to all nodes of the current view. This keyword will create the result-set by combining all rows from both the tables where the condition satisfies i. For those of you who didn't read my previous articles of the Pitfalls Series, you are welcome to bookmark this link, it can help you avoiding common. Suppose you have a dataset containing credit card transactions, including: the date of the transaction; the credit card number; the type of the expense. It only appears to rewrite the. I know I could use aliases to differentiate them (select A. > I could not replicate this in scala code from the shell, just python. CHANGE requires naming the column twice if not renaming it. This is one of the 100+ free recipes of the IPython Cookbook, Second Edition, by Cyrille Rossant, a guide to numerical computing and data science in the Jupyter Notebook. LEFT, RIGHT, or FULL OUTER JOIN: Select all rows from the table on the left (or right, or both) regardless of whether the other table has values in common and (usually) enter NULL where data is missing. To view these steps in action, see the video below:. shape) (142, 6) We have successfully filtered pandas dataframe based on values of a column. Multiple columns can be specificied by using the. If you want to add a column at a specified position, Rename the position column to the new column name For Ex: (OLD_COLUMN_NAME-Hiredate) ALTER TABLE EMP RENAME COLUMN OLD_COLUMN_NAME TO TEMP_HIREDATE;. You can vote up the examples you like or vote down the ones you don't like. If the value of the f column in the A table equals the value of the f column in the B table, it combines data from a1, a2, b1, b2, columns and includes this row in the result set. The problem is that these tables have common columns. If on is a string or a list of strings indicating the name of the join column(s), the column(s) must exist on both sides, and this performs an equi-join. after i want to partitionby columns this condition it importante for me. Matrix which is not a type defined in pyspark. A pseudo-column is an Oracle assigned value (pseudo-field) used in the same context as an Oracle Database column, but not stored on disk. Politically correct effort to rename Austin proves Donald Trump was right. withColumn() method. Syntax: SELECT column_name(s) FROM table_name1 FULL OUTER JOIN table_name2 ON column_name1=column_name2; Example. They are extracted from open source Python projects. It results out all the matching column rows from the first column and if there is no match with the second column, it returns the null value. SQL > ALTER TABLE > Rename Column Syntax. We've already spent an awful lot of time in this series speaking about DataFrames, which are only one of the 3 data structure APIs we can work with in Spark (or one of two data structure APIs in PySpark, if you're keeping score). The column-name join is like a natural join, but it's more flexible. Then, you make a new notebook and you simply import the findspark library and use the init () function. which I am not covering here. We start by writing the transformation in a single invocation, with a few changes to deal with some punctuation characters and convert the text to lower case. In Oracle9ir2, Oracle provides "alter table" syntax to rename data columns in-place in this form: alter table table_name rename column old_column_name TO new_column_name; Here are some examples of Oracle "alter table" syntax to rename data columns. Here's my everyday reference when working on Hadoop and Spark. Spark’s primary data abstraction is an immutable distributed collection of items called a resilient distributed dataset (RDD). how - str, default inner. But I often come across scenarios where I would like the new column names to be created dynamically. DataFrame(data = {'Fruit':['apple. Second, set new value for each column of the table in the SET clause. Date - A date column in a DBMS-specific format. By default, after executing a SELECT statement, the column heading(s) displayed in the result set is the name of the column in the table. THE Job_class column should be able to store character strings up to a maximum length of four, but the column values shouldn't be padded if the value has less than four characters. Second, set new value for each column of the table in the SET clause. Tehcnically, we're really creating a second DataFrame with the correct names. In the Query Editor, you can also right-click on the column you want to rename, and select Rename from the menu that appears. 0 when using pivot () is that it automatically generates pivoted column names with “`” character. Use an existing column as the key values and their respective values will be the values for new column. A tornado warning has. This is very easily accomplished with Pandas dataframes: from pyspark. Example usage below. The Pandas Python library is an extremely powerful tool for graphing, plotting, and data analysis. Matrix which is not a type defined in pyspark. left outer join #9 a9 ON A01. /L1"C/C++" C_LANG Line Comment = // Block Comment On = /* Block Comment Off = */ Escape Char = \ String Chars = "' File Extensions = C CPP CC CXX H HPP AWK PC. I used normal SQL alter command for altering new column but it\'s not working. Then, you make a new notebook and you simply import the findspark library and use the init () function. Using rename to change column names is a much better way than before. Columns of same date-time are stored together as rows in Parquet format, so as to offer better storage, compression and data retrieval. Here's an easy example of how to rename all columns in an Apache Spark DataFrame. Plus, with the evident need for handling complex analysis and munging tasks for Big Data, Python for Spark or PySpark Certification has become one of the most sought-after skills in the industry today. spark pyspark dataframes join. Here is a query that will list all Primary Key columns from a SQL Server table (enter the schema and table name in the WHERE statement - in this case we want to find Primary Key columns from Person. Natural Joins. SQL statements are aimed to Insert, Update or Manipulate, and. When multiple statistics are calculated on columns, the resulting dataframe will have a multi-index set on the column axis. Using Dynamic Rename to Update Column Names in Alteryx August 7, 2016 August 5, 2016 The dynamic rename tool is a great tool if your spreadsheets comes in with lines at the top which have nothing to do with your actual data. by mhn Last Updated October 10, 2017 23:26 PM. Table names and column names are case insensitive. LastName + ', ' + C. :) (i'll explain your. sql import HiveContext, Row #Import Spark Hive SQL hiveCtx = HiveContext(sc) #Cosntruct SQL context. We will show in this article how you can add a column to a pandas dataframe object in Python. Other types of table alterations are possible; see ALTER TABLE statement for more information. So we below we create a dataframe object that has columns, 'W', 'X', and 'Y'. DataNoon - Making Big Data and Analytics simple! In this post, we will be discussing on how to perform different dataframe operations such as a aggregations, ordering, joins and other similar data manipulations on a spark dataframe. Now click on the plus sign next to the Programmability Folder. In this lab we will learn the Spark distributed computing framework. To add a column called email to the contacts table created in Create a basic MySQL table with a datatype of VARCHAR(80), use the following SQL statement: ALTER TABLE contacts ADD email VARCHAR(60); This first statement will add the email column to the end of the table. The dialog allows you to change the name of individual columns by editing the text field or to change the column type by picking one of the possible types in the combo box. The syntax of withColumn() is provided below. Recall the example described in Part 1, which performs a wordcount on the documents stored under folder /user/dev/gutenberg on HDFS. This add the column to all nodes of the current view. withColumn accepts two arguments: the column name to be added, and the Column and returns a new Dataset. OUTER JOIN – Join Multiple Tables. Data Wrangling-Pyspark: Dataframe Row & Columns. For your Information, But it is not good in Table design. This can be done based on column names (regardless of order), or based on column order (i. gov sites: Inpatient Prospective Payment System Provider Summary for the Top 100 Diagnosis-Related Groups - FY2011), and Inpatient Charge Data FY 2011. from pyspark. droplevel) of the newly created multi-index on columns using:. After this is complete, we take the new device columns. CREATE TABLE dbo. Basically I have a lookup column called 'Entity ID' from which the user selects a value before hitting on Save or CheckIn as its a mandatory field. an incorrect. The INNER JOIN selects all rows from both participating tables as long as there is a match between the columns. Use an existing column as the key values and their respective values will be the values for new column. Now the final result doesn’t include the ‘assignee. on - a string for the join column name, a list of column names, a join expression (Column), or a list of Columns. Otherwise, it returns as string. This can be done easily using the function rename() [dplyr package]. This will take you to the listing of all available template application prototypes you can use with BUILD. We use the built-in functions and the withColumn() API to add new columns. The following are code examples for showing how to use pyspark. SQL > ALTER TABLE > Rename Column Syntax. Summary: in this tutorial, you will learn how to use the SQL ADD COLUMN clause of the ALTER TABLE statement to add one or more columns to an existing table. Click into the “Field Name” column of the field that you want to rename and type a new name. The SQL INNER JOIN clause tells the database to only return rows where there is a match found between table1 and table2. If you are creating a new table containing four columns from an existing table and want to change the name of one of the columns when it is created in the new table, add a column list containing ____ names in the CREATE TABLE clause. OrderData ( OrderID int IDENTITY (1,1), ShopCartID int NOT NULL, ShipName varchar (50) NOT NULL, ShipAddress varchar (150. Plz do suggest a right way to do it. Five months after a meteorite made an international splash in Peru, experts are suggesting explanations for some of the space rock's effects - for Duels Customize your avatar with thousands of items, skills, and attributes. Here's my everyday reference when working on Hadoop and Spark. dplyr provides 'rename()' function to, ah — , rename columns, so let's insert a step before the second select step like below. In R, there are multiple ways to select or drop column. Learn the basics of Pyspark SQL joins as your first foray. The syntax allows a list of alter clauses; however, only one table constraint or column constraint can be added, modified, or deleted in each ALTER TABLE statement. Oracle / PLSQL: ALTER TABLE Statement This Oracle tutorial explains how to use the Oracle ALTER TABLE statement to add a column, modify a column, drop a column, rename a column or rename a table (with syntax, examples and practice exercises). Here is an example of nonequi. Here we have taken the FIFA World Cup Players Dataset. To change column names using rename function in Pandas, one needs to specify a mapper, a dictionary with old name as keys and new name as values. The only time the position is an issue is when you use SELECT *. 20 Dec 2017. I don’t want to expand the column width to accommodate this text in one row. sql import HiveContext, Row #Import Spark Hive SQL hiveCtx = HiveContext(sc) #Cosntruct SQL context. There are a couple ways (at least) to rename a column. Direct use of the HBase API, along with coprocessors and custom filters, results in performance on the order of milliseconds for small queries, or seconds for tens of millions of rows. Other types of table alterations are possible; see ALTER TABLE statement for more information. the column is used often in a sort clause (ORDER BY) 6. If you skip it, the UPDATE statement will update data in all rows of the table. If the functionality exists in the available built-in functions, using these will perform better. Revisiting the wordcount example. The dialog allows you to change the name of individual columns by editing the text field or to change the column type by picking one of the possible types in the combo box. In pyspark, when filtering on a udf derived column after some join types, the optimized logical plan results is a java. Modifying Column Labels. Python2 and Python3. For example, if you rename a table column and that column is referenced in a trigger, you must modify the trigger to reflect the new column name. OUTER JOIN – Join Multiple Tables. It is no exaggeration to say that Spark is the most powerful Bigdata tool. Oracle / PLSQL: ALTER TABLE Statement This Oracle tutorial explains how to use the Oracle ALTER TABLE statement to add a column, modify a column, drop a column, rename a column or rename a table (with syntax, examples and practice exercises). By default, after executing a SELECT statement, the column heading(s) displayed in the result set is the name of the column in the table. A natural join compares all columns with the same name for equality. Introduction. Let's try with an example: Create a dataframe:. apply the same logic for Join and answer this question not have the same order of columns, it is better to. This is one of the 100+ free recipes of the IPython Cookbook, Second Edition, by Cyrille Rossant, a guide to numerical computing and data science in the Jupyter Notebook. I then convert Jupyter notebook to a local Spark application and verify the application. PySpark in Jupyter Notebook. e value of the common field will be same. Add a CHECKconstraint to a column. I would like to simplify those kind of names but. If column value not met NULL will be set for the given column. The simple answer (from the Databricks FAQ on this matter) is to perform the join where the joined columns are expressed as an array of strings (or one string) instead of a predicate. Crosstab query techniques. As there are multiple columns in my report and some of which contains long texts without any space or separator. by mhn Last Updated October 10, 2017 23:26 PM. In the video it is done in Excel, but can likewise be applied in Power BI. One option is to drop the top level (using. For your Information, But it is not good in Table design. In Oracle9ir2, Oracle provides "alter table" syntax to rename data columns in-place in this form: alter table table_name rename column old_column_name TO new_column_name; Here are some examples of Oracle "alter table" syntax to rename data columns. One traditional way to handle Big Data is to use a distributed framework like Hadoop but these frameworks require a lot of read-write operations on a hard disk which makes it very expensive in. If you've used R or even the pandas library with Python you are probably already familiar with the concept of DataFrames. Spark data frames from CSV files: handling headers & column types Christos - Iraklis Tsatsoulis May 29, 2015 Big Data , Spark 15 Comments If you come from the R (or Python/pandas) universe, like me, you must implicitly think that working with CSV files must be one of the most natural and straightforward things to happen in a data analysis context. To add a new column to a table, you use the ALTER TABLE ADD COLUMN statement as follows:. A crosstab query is a matrix, where the column headings come from the values in a field. DB Mission¶. If the number of values to be inserted is less than the number of columns in the table, the first n columns are loaded. Python Forums on Bytes. This can be done easily using the function rename() [dplyr package]. Hi I have a dataframe (loaded CSV) where the inferredSchema filled the column names from the file. Learn of SQL alter table add column statement here!. In a previous post, we glimpsed briefly at creating and manipulating Spark dataframes from CSV files. Recall the example described in Part 1, which performs a wordcount on the documents stored under folder /user/dev/gutenberg on HDFS.