Merge pull request #21320 from newrelic/revert-21143-revert-20447-precission-parameter-for-uniqueCount-function

feat(precision argument): Adding the precision argument to the UniqueCount function"

Author: adutta-newrelic

src/content/docs/nrql/nrql-syntax-clauses-functions.mdx

@@ -2115,13 +2115,31 @@ SELECT histogram(duration, 10, 20) FROM PageView SINCE 1 week ago
   <Collapser
     className="freq-link"
     id="func-uniqueCount"
-    title={<InlineCode>uniqueCount(attribute)</InlineCode>}
+    title={<InlineCode>uniqueCount(attribute, [, attribute [, ...]] [, precision: number])</InlineCode>}
   >
-    Use the `uniqueCount()` function to return the number of unique values recorded for an attribute over the time range specified.
 
-    <Callout variant="tip">
-      To optimize query performance, this function returns approximate results for queries that inspect 256 or more unique values.
-    </Callout>
+    Use the `uniqueCount()` function to get the number of unique values recorded for an attribute over a specified time range. To count the unique combinations of multiple attribute values, specify those attributes with the function. You can include up to 32 attributes. This function provides an exact result for up to 256 unique values when you call it without the `precision` argument. For more than 256 unique values, the result is approximate. You can specify a `precision` value within the range of 256 to 50,000 to increase the threshold for exact results. When unique values exceed the set threshold, the function uses the [HyperLogLog probabilistic data structure](https://algo.inria.fr/flajolet/Publications/FlFuGaMe07.pdf) to provide an approximate result.
+
+    Use the `uniqueCount()` function by specifying the attributes and optionally set the precision argument as follows:
+
+    ```sql
+    uniqueCount(attribute, [, attribute [, ...]] [, precision: number])
+    ```
+    * **Attribute(s)**: Specify an attribute for which you want to count unique values, or specify multiple attributes to count unique combinations of values. You can specify up to 32 attributes.
+    * **Precision**: Specify a nuber that sets the threshold for exact results. You can set a value up to 50,000.
+
+    Query example without a `precision` argument:
+
+    ```sql
+    SELECT uniqueCount(accountId) FROM Transaction SINCE 1 day ago
+    ```
+
+    Query example with a `precision` argument:
+
+    ```sql
+    SELECT uniqueCount(foo, bar, baz, precision: 1000) FROM Transaction SINCE 1 day ago
+    ```
+
   </Collapser>
 
   <Collapser