Skip to content
Snippets Groups Projects
Commit d538919c authored by Michael Vogiatzis's avatar Michael Vogiatzis Committed by Tathagata Das
Browse files

[DOCS] Added important updateStateByKey details

Runs for *all* existing keys and returning "None" will remove the key-value pair.

Author: Michael Vogiatzis <michaelvogiatzis@gmail.com>

Closes #7229 from mvogiatzis/patch-1 and squashes the following commits:

e7a2946 [Michael Vogiatzis] Updated updateStateByKey text
00283ed [Michael Vogiatzis] Removed space
c2656f9 [Michael Vogiatzis] Moved description farther up
0a42551 [Michael Vogiatzis] Added important updateStateByKey details
parent 1903641e
No related branches found
No related tags found
No related merge requests found
......@@ -854,6 +854,8 @@ it with new information. To use this, you will have to do two steps.
1. Define the state update function - Specify with a function how to update the state using the
previous state and the new values from an input stream.
In every batch, Spark will apply the state update function for all existing keys, regardless of whether they have new data in a batch or not. If the update function returns `None` then the key-value pair will be eliminated.
Let's illustrate this with an example. Say you want to maintain a running count of each word
seen in a text data stream. Here, the running count is the state and it is an integer. We
define the update function as:
......
0% Loading or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment