Tech

3 minutes read
In Presto, you can use the monthname() function to extract the name of the month from a date. Simply pass the date column or expression as an argument to the monthname() function to get the month name. This function will return the full name of the month in English.How do I convert a date into the corresponding month name string in Presto.
8 minutes read
When dealing with hive locking across Hive and Presto, it is important to understand how locks work in both systems. In Hive, locks are acquired whenever a query is run to prevent conflicts between multiple users accessing the same data simultaneously. These locks are automatically released once the query is completed.In Presto, there is no locking mechanism as queries are executed in an isolated manner, meaning that there is no need to worry about conflicts when running queries concurrently.
6 minutes read
To access data in Google Storage via Presto, you can use the Presto SQL query engine to connect to the Google Cloud Storage bucket where your data is stored. You will need to set up Presto to authenticate with your Google Cloud Storage account, typically using a service account key file.Once you have configured Presto to access Google Storage, you can write SQL queries to select, filter, and manipulate the data stored in your Google Cloud Storage bucket.
4 minutes read
Presto collects runtime memory in various ways during query processing. One common method is by utilizing memory buffers to temporarily store intermediate results and data structures during query execution. This allows Presto to efficiently manage and access data without having to constantly read from disk or reload data from previous stages of processing.Additionally, Presto also dynamically manages memory allocation for various operations such as joins, aggregations, and sorting.
5 minutes read
To perform a left join in Presto SQL, you can use the "LEFT JOIN" or "LEFT OUTER JOIN" keywords in your query. This type of join returns all rows from the left table (the table mentioned before the keyword) and the matched rows from the right table (the table mentioned after the keyword). If there is no match, NULL values are returned for the columns from the right table.Here's an example of a left join in Presto SQL:SELECT table1.column1, table1.column2, table2.
3 minutes read
In Presto, you can write integers using binary notation by prefixing the number with "0b". For example, if you want to write the integer 5 in binary notation, you would write it as 0b101. This indicates that the number 5 is represented in binary form. Similarly, you can write any integer in binary notation by preceding it with "0b" in Presto.How to convert fractions to binary notation in Presto.
6 minutes read
In Presto, the process of deduplication involves removing duplicate rows from a dataset based on specified criteria. One common method to deduplicate in Presto is by using the DISTINCT keyword in a SELECT statement.For example, if you have a table of customer information with duplicate entries for certain customers, you can use a SELECT DISTINCT statement to retrieve only unique rows based on a specific column (e.g. customer ID).
8 minutes read
To debug a Presto server project, you can use debugging tools built into your IDE such as IntelliJ IDEA or Eclipse. These tools allow you to set breakpoints in your code, step through the program line by line, inspect variables, and analyze the flow of execution.Additionally, you can use logging frameworks like SLF4J or Log4j to print debug statements at various points in your code to help identify issues.
3 minutes read
To concatenate arrays grouped by another column in Presto, you can use the array_agg() function along with the GROUP BY clause. First, you group the data by the column you want to group by. Then, you use the array_agg() function to concatenate the arrays within each group. This function creates an array from the values of the given column. Finally, you specify the column you want to concatenate as an argument to the array_agg() function.
3 minutes read
To reference a project with NuGet, you can follow these steps:Open Visual Studio and your project solution.Right-click on the project you want to reference NuGet package in the Solution Explorer.Select "Manage NuGet Packages" from the context menu.In the NuGet Package Manager window, search for the package you want to reference.Click on the package you want to install and then click the "Install" button.