Apache Spark

How to Remove Duplicate Records from Spark DataFrame – Pyspark and Scala

You can create Spark DataFrame with duplicate records. There are no methods that prevent you from adding duplicate records to Spark DataFrame. There are chances that some application such as ETL process may create dataframe with duplicate records. Spark SQL supports several methods to de-duplicate the table. In this article, we will check how to identify and remove duplicate records from Spark SQL DataFrame. Remove Duplicate Records from Spark DataFrame There are many methods that you can use to identify and remove the duplicate records from the Spark SQL DataFrame.…

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June 2, 2021
Snowflake

How to Merge Json Objects in Snowflake?

One of the greatest strengths of Snowflake is that it can handle both structured and semi-structured data. Semi-structured data includes JSON and XML. Snowflake allows you to store and query the json or xml data without using any special functions. The built-in function such as merging two or more json object is not available as of now. But, you can make use of JavaScript function by writing Snowflake user defined function. In this article, we will check how to merge two json objects in Snowflake. Merge JSON Objects in Snowflake…

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June 1, 2021
Snowflake

How Snowflake Internally Handles Updates? – Explanation

When you load data into Snowflake, Snowflake reorganizes that data into micro partition and stores into its internal optimized, compressed, columnar format. Snowflake stores this optimized data in cloud storage. Snowflake uses S3, Blob storage or GCP cloud storage. However, all these storages are immutable. Obviously the question would be how Snowflake internally performs or handles updates when you execute the update command? How Snowflake Internally Handles Updates? Many people would have thought of this question when they were going through Snowflake architecture. It is a complex question. Snowflake uses…

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June 1, 2021
Apache Spark

Spark SQL Recursive DataFrame – Pyspark and Scala

Identifying top level hierarchy of one column from another column is one of the import feature that many relational databases such as Teradata, Oracle, Snowflake, etc support. The relational databases use recursive query to identify the hierarchies of data, such as an organizational structure, employee-manager, bill-of-materials, and document hierarchy. Relational databases such as Teradata, Snowflake supports recursive queries in the form of recursive WITH clause or recursive views. But, Spark SQL does not support recursive CTE or recursive views. In this article, we will check Spark SQL recursive DataFrame using…

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May 31, 2021
Snowflake

Snowflake Array Functions – Syntax and Examples

It is very common practice to store values in the form of an array in the databases. Without a doubt, Snowflake supports many array functions. You can use these array manipulation functions to manipulate the array types. In this article, we will check how to work with Snowflake Array Functions, syntax and examples to manipulate array types. Snowflake Array Functions Following is the list of Snowflake array functions with brief descriptions: Array FunctionsDescriptionARRAY_AGGFunction returns the input values, pivoted into an ARRAY.ARRAY_APPENDThis function returns an array containing all elements from the…

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May 26, 2021
Apache Spark

Spark SQL and Dataset Hints Types- Usage and Examples

In general, Query hints or optimizer hints can be used with SQL statements to alter execution plans. Hints let you make decisions that are usually made by the optimizer while generating an execution plan. As a data architect, you might know information about your data that the optimizer does not know. Hints provide a mechanism to direct the optimizer to choose a certain query execution plan based on the specific criteria. In this article, we will check Spark SQL and Dataset hints types, usage and examples. Spark SQL and Dataset…

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May 24, 2021
Snowflake

What are SELECT INTO Alternatives in Snowflake?

In my other post, I have discussed about what are different methods to create Snowflake table. There are many database specific syntaxes that are not supported in Snowflake yet. One of such syntax is SELECT INTO. The databases such as SQL Server, Reshift, Teradata, etc. supports SELECT INTO clause to create new table and insert the resulting rows from the query into it. In this article, we will check what are SELECT INTO alternatives in Snowflake with some examples. SELECT INTO Alternatives in Snowflake In the databases such as SQL…

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April 16, 2021
Snowflake

What are Different Methods to Create Snowflake Tables?

In my other posts, I have discussed on how to create Snowflake clustered tables, creating external tables in Snowflake, etc. In this article, we will check what are different methods to create Snowflake tables with some basic examples. Different Methods to Create Snowflake Tables During database development, developer create a table such as permanent, temporary or transient tables as per the requirement. Developers usually create tables using DDL such as “CREATE TABLE” statement. But, sometimes you may need to use different methods such as creating a copy of an existing…

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April 16, 2021
General

How to Duplicate or Clone SQL Tables – Methods

In an application development, there may be situations where you need to create a similar table of the table which is already present in the database. In other words, you need to create a duplicate or clone of the existing table. The methods to duplicate or clone SQL table vary from database to database. For example, data warehouse such as Snowflake, Redshift provide methods which are not present in any other databases. In this article, we will check basic methods that you can use to clone or duplicate SQL tables…

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April 15, 2021
Redshift

Different Methods to Create Redshift Tables – Examples

In my other posts, I have discussed various methods to create Redshift table from Spark DataFrame, Redshift Temporary tables, creating an index on Redshift tables, etc. In this article, we will check different methods and approach to create Amazon Redshift tables. We will also check differences between various methods to create tables in Redshift. Different Methods to Create Redshift Tables During development, developer create a table either permanently or temporarily as per the requirement. Developers usually create tables using DDL such as “CREATE TABLE” statement. But, sometimes you may need…

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April 14, 2021