Amazon Redshift provides Date and Time functions among other functions that provide functional access to the date and time module in the data warehouse. These Date and Time functions are Scalar functions that can be used to query timeline data as well as update them in Redshift. But, why are these functions needed?
Date and Time functions are used to generate sample data based on a specified timeline and also report the timeline of an operation. They are also used to provide input values in the date format that can serve as arguments to other functions when needed during query execution or for system diagnosis.
In this article, you would learn briefly about Date and Time functions in Redshift, how to use the Redshift SYSDATE Function, and also see sample queries where the Redshift SYSDATE function is implemented.
Table of Contents
- Understanding Date & Time Functions in Redshift
- Types Of Date & Time Functions
- Understanding the Redshift SYSDATE Function
- Working with the Redshift SYSDATE Function
Understanding Date & Time Functions in Redshift
Date and Time functions in Redshift are used for accessing the date and time module. They serve the primary purpose of enabling the database users the functionality of time-based queries. Time-based operations in this case could be concerning when certain tables were created and manipulating the date/time values in the tables.
However, these functions can be used specifically. They contain date-only functions that can be used for the execution of date-specific queries. They can also be modified in terms of output. Examples of these functions include CENTURY, EPOCH, and DECADE. These functions will be highlighted in more detail in the succeeding section.
Another key point to note is that these functions are not the same. They serve different purposes and require different levels of access. In the next section, we would go over the two groups of Date and Time functions in Redshift.
Types Of Date & Time Functions
- Date and Time functions in Transactions: These are also called Transactional functions. They are used during the execution of queries. They operate in real-time as the query is being executed and give their results in real-time. Examples include:
- Deprecated Leader Node-Only Functions: Usually, Amazon Redshift queries are distributed and run either on the compute nodes or exclusively on the leader node. The leader node runs queries that either reference catalog tables(tables with the PG naming prefix) or do not reference any table. The leader node on the other hand distributes queries that reference user-created tables or system tables to the compute nodes. Examples include:
Of all these functions, only a few render their results in more than a timestamp. This provides an added advantage because timestamps are mutable(i.e they can be manipulated). To read more about Date & Time functions, refer to AWS Docs and Redshift Date Functions Blog.
Understanding the Redshift SYSDATE Function
The Redshift SYSDATE Function returns the current date and time in the current session time zone(in UTC by default). The current session started refers to the date and time during a transaction in the current transaction. Syntactically, this function takes no argument.
Argument: The Redshift SYSDATE function takes no arguments.
Return Type: The execution of the Redshift SYSDATE function returns the start date or time of the current transaction as a Timestamp. The timestamp is represented in the format YYYY-MM-DD H:M:S except it is modified.
Simplify Amazon Redshift ETL with Hevo’s No-code Data Pipeline
Hevo Data, a No-code Data Pipeline, helps load data from any data source such as Databases, SaaS applications, Cloud Storage, SDK,s, and Streaming Services and simplifies the ETL process. It supports 100+ Data Sources including 40+ Free Sources. It is a 3-step process by just selecting the data source, providing valid credentials, and choosing the destination.
Hevo loads the data onto the desired Data Warehouse such as Amazon Redshift in real-time and enriches the data and transforms it into an analysis-ready form without having to write a single line of code. Its completely automated pipeline, fault-tolerant, and scalable architecture ensure that the data is handled in a secure, consistent manner with zero data loss and supports different forms of data. The solutions provided are consistent and work with different BI tools as well.GET STARTED WITH HEVO FOR FREE
Check out why Hevo is the Best:
- Secure: Hevo has a fault-tolerant architecture that ensures that the data is handled securely and consistently with zero data loss.
- Schema Management: Hevo takes away the tedious task of schema management & automatically detects the schema of incoming data and maps it to the destination schema.
- Minimal Learning: Hevo, with its simple and interactive UI, is extremely simple for new customers to work on and perform operations.
- Hevo Is Built To Scale: As the number of sources and the volume of your data grows, Hevo scales horizontally, handling millions of records per minute with very little latency.
- Incremental Data Load: Hevo allows the transfer of data that has been modified in real-time. This ensures efficient utilization of bandwidth on both ends.
- Live Support: The Hevo team is available round the clock to extend exceptional support to its customers through chat, email, and support calls.
- Live Monitoring: Hevo allows you to monitor the data flow and check where your data is at a particular point in time.
Simplify your Redshift ETL with Hevo today!SIGN UP HERE FOR A 14-DAY FREE TRIAL!
Working with the Redshift SYSDATE Function
The Redshift SYSDATE function can be used in a number of ways depending on the user’s need. Let’s understand the queries you can implement to get the information required using the Redshift SYSDATE function.
1) Get Timestamp
Query to get Timestamp:
The query above would return the timestamp in the format YYYY-MM-DD H:M:S. This timestamp can serve as an input to another Redshift function.
2) Get Date
To return the current date with the time excluded, the Redshift SYSDATE function is placed inside the TRUNC function.
Query to get only date:
This query would return only the current date in the format YYYY-MM-DD.
3) Query Tables with Date Values
The Redshift SYSDATE function can be used to get results based on the date values present. In the example query below, we would return a result set based on the sale time of products between the current date and 100 days earlier.
Query using date values and TRUNC:
SELECT PRODUCTID, PRICE, TRUNC(SALETIME) as SALETIME, TRUNC(SYSDATE) AS NOW WHERE SALETIME BETWEEN TRUNC(SYSDATE) - 100 AND TRUNC(SYSDATE) ORDER BY SALETIME DESC;
The query above would return a result set(table specifically) containing the sales information of products in the format – productid, price, saletime between now and 100 hundred days earlier. Notice the use of the TRUNC function to return only the date as needed and also the NOW statement to use the current date.
As seen in the sample queries above, the Redshift SYSDATE Function can be used for analysis based on timeline period as well as for system diagnostics by the system administrator.
Additionally, apart from using the TRUNC function to return only the date, other functions such DATE_PART and EXTRACT can be used to achieve almost the same. For example, the query below demonstrates the use of DATE_PART and EXTRACT to extract the minute for the final result.
Query to get timestamp using EXTRACT and DATE_PART:
SELECT EXTRACT(minute from sysdate); SELECT DATE_PART(minute, sysdate);
The queries above will return a timestamp containing hour, seconds, day, month, and year but not the minute.
The queries written above show the flexibility of the Date and Time functions in Redshift and the versatility of the Redshift SYSDATE Function. To read more about the Redshift SYSDATE Function, refer to AWS Documentation.
In this article, you have learned briefly about Date and Time functions in Redshift and how to work with the Redshift SYSDATE function. Amazon Redshift provides several functions that work for both transactional processes and system diagnostics if the need arises. Redshift SYSDATE is one of such functions.
However, extracting complex data from a diverse set of data sources like Databases, CRMs, Project management Tools, Streaming Services, Marketing Platforms to your Amazon Redshift can be quite challenging. This can be quite challenging. This is where a simpler alternative like Hevo can save your day!
Hevo Data is a No-Code Data Pipeline that offers a faster way to move data from 100+ Data Sources including 40+ Free Sources, into your Data Warehouse such as Amazon Redshift to be visualized in a BI tool. Hevo is fully automated and hence does not require you to code.VISIT OUR WEBSITE TO EXPLORE HEVO
Want to take Hevo for a spin?
Share your experience with the Redshift SYSDATE Function in the comments section below!