PrestoDB Questions & Answers

Answers to your questions about PrestoDB

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Presto Pivot Rows to Columns | Rows to Columns via Rotation | Ahana

November 18, 20202 min read

How to Rotate Rows to Columns with Presto Sometimes called pivoting, here is one example of how to switch columns to rows via rotation with Presto.   Suppose we have rows … Continue reading Presto Pivot Rows to Columns | Rows to Columns via Rotation | Ahana

How do you rotate columns to rows with Presto?

November 18, 20201 min read

Sometimes called unpivoting, here is one example of how to rotate column data with Presto.   Suppose we have some integer data arranged in two columns called a and b: a … Continue reading How do you rotate columns to rows with Presto?

Benefits Of Using Managed Service For Presto | Ahana

November 11, 20203 min read

What are the operational benefits of using a managed service for Presto with Ahana Cloud? First let’s hear from an AWS Solution Architect: “Ahana Cloud uses the best practices of … Continue reading Benefits Of Using Managed Service For Presto | Ahana

Presto Explode Array | Lateral View Explode in Presto | Ahana

November 11, 20202 min read

How to Lateral View Explode in Presto Hive’s explode() function takes an array (or a map) as input and outputs the elements of the array (map) as separate rows. Explode … Continue reading Presto Explode Array | Lateral View Explode in Presto | Ahana

How do you cross join unnest a JSON array?

November 11, 20202 min read

Let’s take a look at how you can cross join unnest a JSON array by doing Presto joins. Here’s an example using test results data in json form as input, … Continue reading How do you cross join unnest a JSON array?

How can you write the output of queries to S3 easily?

November 10, 20201 min read

With Ahana Cloud, we’ve made it easy for you write output of queries to S3. While there’s a variety of formats, here’s an example:

Does Amazon Athena do joins across other data sources besides S3? Does Amazon Athena connect to other data sources?

November 5, 20201 min read

With Amazon Athena you’re limited in scope when it comes to doing joins across other data sources like relational data systems and more. You have to set up a Lambda, … Continue reading Does Amazon Athena do joins across other data sources besides S3? Does Amazon Athena connect to other data sources?

If I have catalogs connected and configurations attached to my Presto cluster, what happens when I take the cluster down?

November 5, 20201 min read

If you’re managing Presto on your own, either through your own installation or through a service like AWS EMR or AWS Athena, you have to maintain and manage all of … Continue reading If I have catalogs connected and configurations attached to my Presto cluster, what happens when I take the cluster down?

Presto Map | Check If Map Or Presto Array Is Empty Or Contains | Ahana

October 30, 20202 min read

Check If Map Or Presto Array Is Empty Or Contains When working with array (indexable lists) or map (key-value tuple) complex types in Presto, it is useful to be able … Continue reading Presto Map | Check If Map Or Presto Array Is Empty Or Contains | Ahana

Export Result Of Select Statement in Presto | Presto Export to CSV | Ahana

October 30, 20203 min read

Export Result Of Select Statement in Presto A common question is “how can I run a query and export result of select statement quickly and easily in Presto?”  You are … Continue reading Export Result Of Select Statement in Presto | Presto Export to CSV | Ahana

Presto Queries Running Slow | Slow Queries & Presto Tuning | Ahana

October 23, 20206 min read

How to Manage Presto Queries Running Slow There are a few reasons that Presto performance is impacted and queries might be running slow. Below we’ll share some things to do … Continue reading Presto Queries Running Slow | Slow Queries & Presto Tuning | Ahana

Presto JSON | Extract Keys In A Nested JSON Array Object | Ahana

October 14, 20202 min read

Extract Keys in a Nested JSON Array Object With Presto Let’s say we have some JSON that looks like this: In this instance our json contains key value pairs. How … Continue reading Presto JSON | Extract Keys In A Nested JSON Array Object | Ahana

Generate Interval from Variable Using PrestoDB | Ahana

October 14, 20203 min read

Generate Interval from Variable Using PrestoDB There are numerous ways to generate interval from variable using PrestoDB SQL for different data types. Dates Date intervals can be generated for a … Continue reading Generate Interval from Variable Using PrestoDB | Ahana

How To Presto Escape Single Quote | Presto Escape Quote | Ahana

October 12, 20202 min read

How to Presto Escape a Single Quote In reality there will be some occasions when you need to use a quote character in your data, in your query, or in … Continue reading How To Presto Escape Single Quote | Presto Escape Quote | Ahana

Check If Null & Return Default (NVL analog) | Ahana

October 3, 20204 min read

Check if null and return default (NVL analog) SQL has a number of functions for dealing with null values, and everyone has their favorite. The complicating factor is that not … Continue reading Check If Null & Return Default (NVL analog) | Ahana

Static Date & Timestamp In Where Clause | PrestoDB Timestamp

October 3, 20202 min read

Static date and timestamp in where clause In this post we’ll look at the static date and timestamp in where clause when it comes to Presto. Many databases automatically convert … Continue reading Static Date & Timestamp In Where Clause | PrestoDB Timestamp

Where Can I Find The Presto Server Bootstrap Logs | Ahana

October 3, 20203 min read

Where can I find the Presto Server Bootstrap logs? A common question is “where can I find the Presto server bootstrap logs?”  These are logs that indicate what is happening … Continue reading Where Can I Find The Presto Server Bootstrap Logs | Ahana

Where Can I Find Different Presto Metrics For Monitoring | Ahana

October 3, 20205 min read

Where can I find different Presto metrics for monitoring? If you’re wondering “Where can I find different Presto metrics for monitoring?”, we’ll help explain it. There are several ways to … Continue reading Where Can I Find Different Presto Metrics For Monitoring | Ahana

Where To Find Presto Logs | Presto Logs EMR | Ahana

October 3, 20204 min read

Where to Find Presto Logs If you’re wondering “where do I find Presto logs”, we’ll help explain it. Presto needs a data directory for storing logs, etc. and it is … Continue reading Where To Find Presto Logs | Presto Logs EMR | Ahana

Presto Equivalent Of mysql group_concat | group_concat Presto

October 3, 20204 min read

Presto equivalent of mysql group_concat PrestoDB supports ANSI SQL and includes support for several SQL dialects, including MySQL dialect, making it easy to group and aggregate data in a variety … Continue reading Presto Equivalent Of mysql group_concat | group_concat Presto

Presto CLI Download | How to Get the Presto CLI Tool | Ahana

September 29, 20204 min read

How to Get the Presto CLI Tool The Presto CLI provides a terminal-based interactive shell for running queries. The CLI is a self-executing JAR file, which means it acts like … Continue reading Presto CLI Download | How to Get the Presto CLI Tool | Ahana

Convert Date String to Date Format in Presto | Presto Date Function | Ahana

September 17, 20204 min read

How To Convert Date String to Presto Date Format PrestoDB supports ANSI SQL and includes support for several SQL dialects, so it’s straightforward to convert a date string to date … Continue reading Convert Date String to Date Format in Presto | Presto Date Function | Ahana

Where to Find Presto Source Code | PrestoDB Source Code GitHub | Ahana

September 15, 20204 min read

Where to Find Presto Source Code & How to Work With It The main branch: PrestoDB source code Presto is an open source project that is developed in the open … Continue reading Where to Find Presto Source Code | PrestoDB Source Code GitHub | Ahana