PrestoDB Questions & Answers
Answers to your questions about PrestoDB
Learn how to run a CTAS with a query. This article explains the two simplest options to get up and going.
Trying to learn the difference between a managed table and external tables? This article explains it and provides guidance
What are the AWS Glue partition limits and does it apply to AWS Athena? Typically you’ll use AWS Glue to create the data sources and tables that Athena will query. … Continue reading AWS Glue Partition Limits For AWS Athena | Ahana
What level of concurrency performance can I expect using Presto as part of the AWS Athena service? I’m getting a lot of my workloads queued up when I use AWS … Continue reading Concurrency Performance Using Presto With AWS Athena Service | Ahana
Amazon Athena is an interactive query service based on Presto that makes it easy to analyze data. Learn how to get deterministic performance.
Do I have to use AWS Lambda to connect to data sources with Athena? The Athena Federated Query Journey AWS announced the public preview of Athena federated query in November … Continue reading Using AWS Lambda To Connect To Data Sources With Athena | Ahana
How do I do geospatial queries and spatial joins in Presto? A question that often comes up is “how do I do geospatial queries and spatial joins in Presto?”. Fortunately … Continue reading Geospatial Queries & Spatial Joins In Presto Guide | Ahana
How do I query JSON documents with Presto? JSON documents are a common data type. A lot of people collect logs and load them into S3. Querying JSON with Presto … Continue reading How Do I Query JSON Documents With Presto | Query JSON Docs | Ahana
Is there latency overhead for Presto queries if everything fits into memory and doesn’t need to be distributed? Presto is both in-memory and distributed, so each work has memory and … Continue reading Latency Overhead For Presto Queries If Fits Into Memory | Ahana
Is the Hive metastore a hard dependency of Presto, or could Presto be configured to use something else like Postgres? With Presto, there’s no hard dependency of having to use … Continue reading Is Hive Metastore Hard Dependency Of Presto | Postgres With Presto | Ahana
The Differences Between Apache Drill vs Presto Drill is an open source SQL query engine which began life as a paper “Dremel: Interactive Analysis of Web-Scale Datasets” from Google in … Continue reading What are the differences between Presto and Apache Drill?
Why am I getting zero records when I use AWS Athena to query a CSV file? There’s a common error many AWS Athena users see when they query CSV files … Continue reading Zero Records Returned CSV | Zero Records AWS Athena | Ahana
Does Presto work natively with GraphQL? Some users may have a primary data store that is GraphQL-based (AWS AppSync) and want to leverage Presto. For context, GraphQL falls in the … Continue reading Presto Graphql | Does Presto Work Natively With GraphQL | Ahana
Why does a single AWS Athena query get stuck in QUEUED state before being executed? One of the drawbacks of AWS Athena is the fact that as a user, you … Continue reading Athena Query Waiting In Queue or Athena Query Stuck In Queued State
How Presto Joins Data Because Presto is a distributed system composed of a coordinator and workers, each worker can connect to one or more data sources through corresponding connectors. The … Continue reading How Presto Joins Data | Presto Data Connectors & Join Example | Ahana
Using Spark’s Execution Engine With Presto Learn when to use Spark as an additional engine alongside open-source Presto, and how you can configure and invoke a Spark job from Presto. … Continue reading Using Spark’s Execution Engine With Presto – Quick Guide | Ahana
When I run a query with AWS Athena, I get the error message ‘query exhausted resources on this scale factor’. Why? AWS Athena is well documented in having performance issues, … Continue reading Query Exhausted Resources On This Scale Factor Error | Ahana
Creating tables in a S3 Bucket gives “Query failed External location must be a directory” So here’s why you are here. You are using Presto’s Hive connector and you want … Continue reading Creating Tables In A S3 Bucket Issues | Ahana
Big Data Query When it comes to querying big data using standard SQL you have come to the right place as this is what Presto was designed to do. Presto, … Continue reading Big Data Query | Presto Big Data | Ahana
I use RDS Postgres databases and need some complex queries done which tend to slow down my databases for everyone else on the system. What do I need to consider … Continue reading RDS Postgres Databases Complex Queries | Ahana
Complex SQL Queries Complex SQL queries benefit from Presto’s distributed, parallel, in-memory processing architecture and cost-based optimizer. And with Presto’s federation capabilities even more complex queries can be unleashed on … Continue reading Complex SQL Queries | SQL Complex Queries | Ahana
Advanced SQL Queries with Presto Advanced SQL features and functions are used by analysts when, for example, complex calculations are needed, or when many tables (perhaps from multiple sources) need … Continue reading Advanced SQL Queries with Presto | SQL Queries Presto | Ahana
How To Stop Presto If you are using the presto-admin tool this is how to stop Presto safely: $ presto-admin server stop In addition these commands are also useful: presto-admin … Continue reading How to Stop Presto Tutorial | EMR Restart Presto Tutorial | Ahana
Presto New Releases Where is the latest release of PrestoDB? And where can I find the release notes? Where is the documentation? These are common questions with easy answers. Presto’s … Continue reading Presto New Releases & Latest Release
How Much Memory To Give A Presto Worker Node Presto is an in-memory query engine and so naturally memory configuration and management is important. A common question that comes up is … Continue reading How Much Memory To Give A Presto Worker Node | Presto Memory | Ahana
How to Show Tables From All Schemas with Presto In Presto it is straightforward to show all tables in a schema e.g. If we have a MySQL data source/catalog that … Continue reading Show Tables From Schemas With Presto | Presto Information_Shema | Ahana
How To Convert Bigint to Timestamp with Presto UNIX timestamps are normally stored as doubles. If you have UNIX timestamps stored as big integers then you may encounter errors when … Continue reading Convert Presto Bigint To Timestamp | Bigint To Timestamp Presto | Ahana
Case Sensitive Search Configuration with Presto When dealing with character data, case sensitivity can be important when searching for specific matches or patterns. But not all databases and query engines … Continue reading Case Sensitive Search Configuration with Presto | Presto Regex | Ahana
When should I use ORC versus Parquet when using Presto? If you’re working with open data lakes using open source and open formats, you can have multiple formats. Presto works … Continue reading Use ORC Versus Parquet When Using Presto | Ahana
What’s the advantage of having your own Hive metastore with Presto? How does it compare to Amazon Glue? First let’s define what Apache Hive is versus Amazon Glue. Apache Hive … Continue reading Benefits Of Hive Metastore With Presto | Ahana
How to Find Out Data Type of Value with Presto Presto has a typeof() function to make finding out data types of values easy. This is particularly useful when you … Continue reading Find Out Data Type of Value with Presto | Presto Check Data Type | Ahana
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
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?
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
Let’s take a look at how you can cross join unnest a JSON array by using 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 in Presto?
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?
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?
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?
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 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
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. Follow along with 3 simple examples to get up and going.
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
SQL has a number of functions for dealing with null values. Not all SQL engines support all functions. Use this as a guide to check if null.
Understand timestamp and static date in where clause. Learn how to use it with PrestoDB. Use this article as a guide to better navigate PrestoDB.
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 you find different Presto metrics for monitoring? Learn how to easily find and monitor metrics with this article.