Year: 2019

Grouping Numbers in Snowflake – Part 2

Grouping Numbers in Snowflake – Part 2

In a previous post, I showed a way to format numbers using local grouping characters. One of the advantages of the approach is it will work everywhere across Snowflake since it does not require creation of a User Defined Function (UDF).

Using a UDF provides a lot more power and flexibility, so let’s see how we do that. First, you need to be working with a specific Snowflake Database and have an active Data Warehouse to do any processing including creation of a UDF.

use database TEST_DATABASE;
use warehouse TEST_WAREHOUSE;

Next we need to create the User Defined Function (UDF):

--Return a formatted number with locale-specific grouping and decimal characters.
create or replace function FormatNumber(d double)
  returns string
  language javascript
  strict
  as '
	if (!isNaN(D)){
    	return D.toLocaleString("en-US");
    } else {
    	return "Not a number.";
    }
  ';

Of course, we could create a much more sophisticated function with overloads that handles optional local input, etc., but for the purposes of this function that’s overkill. If we need to adjust the locale, we can do that easily in the function by changing the parameter sent to the “toLocaleString”. Note that if you omit this parameter, the function will use the default for the current machine. In my case, the machine is in the US-East region of AWS, so it’s already set to US English, “en-US”, but to be on the safe side, it’s best to specify the right value.

To test the function, we can issue this SnowSQL statement (note that we need to be using the same database as the one where we created the UDF):

--Optionally set the database context if it's changed.
use database TEST_DATABASE;

select formatnumber(123456789.012) as FORMATTED_NUMBER;

When the locale specified US English, “us-EN”, it will return the following:

To get a list of possible values for the locale parameter worldwide, refer to the Mozilla Developer Network documentation here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/toLocaleString

One of the options on that page is for Han Chinese. I don’t know how to read that, but when I set the locale in the Snowflake UDF to zh-Hans-CN-u-nu-hanidec I’ll assume it’s working just fine when it returns the following result:

Perhaps someone who can read Han Chinese can confirm this for me.

Grouping Numbers in Snowflake

Grouping Numbers in Snowflake

As I started working with Snowflake, one of the things I noticed is that large integers appear without grouping symbols. When counting rows in a table, it may display as 752941241 rows. Without counting the digits, it’s hard to see at a glance if this is about 75 million rows or 750 million rows.

After reading the docs, I found a simple way to format long numbers with grouping digits.

select to_varchar(count(*), '999,999,999') as TRIP_COUNT from trips;

I’m using a large number in the format string because when a the first argument in to_varchar exceeded the capacity of the number in the format string, the function will return ###,###. Be sure to use a format string large enough for any return. I have tested it with format strings as large as 999,999,999,999,999,999,999 (that’s twenty one 9’s). If the format string is larger than the required number of digits, the function will return the right sized formatted number without leading spaces or zeros.

You can also specify a decimal point using dot character. For example, to show a number with grouped digits and a decimal point:

select to_varchar(some_column, '999,999,999.999999999') from some_table;

This will show up to the maximum number of digits specified in the format string. but will not show more than are necessary. The decimal point will always show up, even when there’s no decimal portion of the number. I will see if there’s a way to format this better and update here.

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Snowflake in Raleigh/Durham

Snowflake in Raleigh/Durham

Hi there. My name is Greg Pavlik, and I’m a Sr. Sales Engineer at Snowflake Computing based in Raleigh-Durham. I created this site to share tips, tricks, and random thoughts on all things Snowflake Computing.

Snowflake is the only data warehouse built from the ground up for the cloud. You can find more about Snowflake at https://snowflake.com.

Although I am a Snowflake employee, this is not an official Snowflake Computing source of information. It’s intended to help others with SQL syntax, project ideas, data integration and more.

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