# How to use batch node with concatenate sequences mode

**URL:** <https://discourse.nodered.org/t/how-to-use-batch-node-with-concatenate-sequences-mode/20709>\
**Category:** General\
**Created:** [22 January 2020 03:43 UTC](https://discourse.nodered.org/t/how-to-use-batch-node-with-concatenate-sequences-mode/20709 "2020-01-22T03:43:55Z")\
**Posts on this page:** 12\
**Page:** 1

<div class="post-metadata">

**Author:** ![ab73863](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/ab73863/32/11144_2.png) [@ab73863](https://discourse.nodered.org/u/ab73863)\
**Post date:** [22 January 2020 03:43 UTC](https://discourse.nodered.org/t/how-to-use-batch-node-with-concatenate-sequences-mode/20709/1 "2020-01-22T03:43:55Z")

</div>

Hello,

I am trying to understand the batch node with **concatenate sequences mode**. I am not able find any examples related to usage of this node in **concatenate sequences mode**.

Could anyone please share a sample or pointer to any documentation which shows how to use this particular mode?

Regards  
Arun

---

<div class="post-metadata">

**Author:** ![Trying\_to\_learn](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/trying_to_learn/32/28400_2.png) [@Trying\_to\_learn](https://discourse.nodered.org/u/Trying_to_learn)\
**Post date:** [22 January 2020 05:34 UTC](https://discourse.nodered.org/t/how-to-use-batch-node-with-concatenate-sequences-mode/20709/2 "2020-01-22T05:34:43Z")

</div>

Hi.

Ok, sorry. You used the `batch` node.

I think it would be easier if you use the `join` node.

Like this:

Given you send message 4 last.

```auto
[{"id":"e3630952.9b58d","type":"inject","z":"184dc884.7aba5f","name":"","topic":"","payload":"Message 1","payloadType":"str","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":200,"y":1640,"wires":[["dd4306f7.660f48"]]},{"id":"4bb46cb3.3777ec","type":"inject","z":"184dc884.7aba5f","name":"","topic":"","payload":"Message 2","payloadType":"str","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":200,"y":1680,"wires":[["dd4306f7.660f48"]]},{"id":"b7093225.f3c128","type":"inject","z":"184dc884.7aba5f","name":"","topic":"","payload":"Message 3","payloadType":"str","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":200,"y":1720,"wires":[["dd4306f7.660f48"]]},{"id":"db7a2c52.ed5328","type":"inject","z":"184dc884.7aba5f","name":"","topic":"","payload":"Message 4","payloadType":"str","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":200,"y":1760,"wires":[["b69084cc.63b918"]]},{"id":"772c4a91.8c54dc","type":"debug","z":"184dc884.7aba5f","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","x":700,"y":1700,"wires":[]},{"id":"dd4306f7.660f48","type":"join","z":"184dc884.7aba5f","name":"","mode":"custom","build":"string","property":"payload","propertyType":"msg","key":"topic","joiner":"\\n","joinerType":"str","accumulate":false,"timeout":"","count":"","reduceRight":false,"reduceExp":"","reduceInit":"","reduceInitType":"","reduceFixup":"","x":560,"y":1700,"wires":[["772c4a91.8c54dc"]]},{"id":"b69084cc.63b918","type":"change","z":"184dc884.7aba5f","name":"","rules":[{"t":"set","p":"complete","pt":"msg","to":"4","tot":"num"}],"action":"","property":"","from":"","to":"","reg":false,"x":380,"y":1760,"wires":[["dd4306f7.660f48"]]}]

```

---

<div class="post-metadata">

**Author:** ![kuema](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/kuema/32/6542_2.png) [@kuema](https://discourse.nodered.org/u/kuema)\
**Post date:** [22 January 2020 06:24 UTC](https://discourse.nodered.org/t/how-to-use-batch-node-with-concatenate-sequences-mode/20709/3 "2020-01-22T06:24:12Z")

</div>

I am using the batch node to create bulk inserts for my InfluxDB. It aggregates points from multiple sources for 10s, re-joins them into an array sends it in one operation.

Here's an example:

```auto
[{"id":"10cf2688.297669","type":"batch","z":"af129d0b.bf6878","name":"","mode":"interval","count":10,"overlap":0,"interval":10,"allowEmptySequence":false,"topics":[],"x":450,"y":260,"wires":[["17aa7e85.166589"]]},{"id":"17aa7e85.166589","type":"join","z":"af129d0b.bf6878","name":"","mode":"auto","build":"string","property":"payload","propertyType":"msg","key":"topic","joiner":"\\n","joinerType":"str","accumulate":false,"timeout":"","count":"","reduceRight":false,"reduceExp":"","reduceInit":"","reduceInitType":"","reduceFixup":"","x":630,"y":260,"wires":[["7bf361b8.9906e8"]]},{"id":"ec7d48bf.d27de8","type":"inject","z":"af129d0b.bf6878","name":"","topic":"","payload":"","payloadType":"date","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":280,"y":260,"wires":[["10cf2688.297669"]]},{"id":"7bf361b8.9906e8","type":"debug","z":"af129d0b.bf6878","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","x":810,"y":260,"wires":[]}]

```

---

<div class="post-metadata">

**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [22 January 2020 08:57 UTC](https://discourse.nodered.org/t/how-to-use-batch-node-with-concatenate-sequences-mode/20709/4 "2020-01-22T08:57:14Z")

</div>

Your flow does not appear to demonstrate what you are trying to do. As the batch node is configured it is just repeating the incoming messages. Can you provide a flow showing in more detail what you are trying to do.

---

<div class="post-metadata">

**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [22 January 2020 09:01 UTC](https://discourse.nodered.org/t/how-to-use-batch-node-with-concatenate-sequences-mode/20709/5 "2020-01-22T09:01:08Z")

</div>

As @Trying_to_learn has suggested, if you have data coming in from various sources with different topics and want to generate a message built over a period to pass to influx then this would be the usual way to do it.

 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/6/8/6898b49ff325f27d0eb588a892d857940cef714a.png)  
If the topics contain the influx field names then you can feed the output direct to the influx node.

---

<div class="post-metadata">

**Author:** ![kuema](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/kuema/32/6542_2.png) [@kuema](https://discourse.nodered.org/u/kuema)\
**Post date:** [22 January 2020 09:21 UTC](https://discourse.nodered.org/t/how-to-use-batch-node-with-concatenate-sequences-mode/20709/6 "2020-01-22T09:21:37Z")

</div>

It was just a general example to demonstrate to the OP what the batch node is doing. It's not related to InfluxDB or my use-case.

Neither am I using msg.topic. In my specific use-case the batch node is collecting ready-to-insert Influx point objects coming from different sources over a timespan of 10s. The output of the batch node (all points within those 10s) is then joined into an array and given to the Influx batch insert node. 🙂

I have been using this pattern for some time now to optimize inserts into my databases.

---

<div class="post-metadata">

**Author:** ![kuema](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/kuema/32/6542_2.png) [@kuema](https://discourse.nodered.org/u/kuema)\
**Post date:** [22 January 2020 09:29 UTC](https://discourse.nodered.org/t/how-to-use-batch-node-with-concatenate-sequences-mode/20709/7 "2020-01-22T09:29:10Z")

</div>

Oops... I just realized I misread the OP's post, he's using the **concatenate sequences mode**. 😳

It was before my morning coffee, a bit too early it seems. 🙈 So please ignore everything I wrote above, sorry.

---

<div class="post-metadata">

**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [22 January 2020 09:45 UTC](https://discourse.nodered.org/t/how-to-use-batch-node-with-concatenate-sequences-mode/20709/8 "2020-01-22T09:45:51Z")

</div>

Sorry, I thought @kuema was the OP. Please disregard my posts also.

---

<div class="post-metadata">

**Author:** ![kuema](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/kuema/32/6542_2.png) [@kuema](https://discourse.nodered.org/u/kuema)\
**Post date:** [22 January 2020 09:55 UTC](https://discourse.nodered.org/t/how-to-use-batch-node-with-concatenate-sequences-mode/20709/9 "2020-01-22T09:55:44Z")

</div>

No problem.

But - like the OP - I have yet to come up with an actual, real-world use-case for the **concatenate sequences mode**. I wonder what the intention was, especially with the topic handling that is mentioned in the docs:

> Concatenate Sequences
> 
> creates a message sequence by concatenating incoming sequences. Each message must have a `msg.topic` property and a `msg.parts` property identifying its sequence. The node is configured with a list of `topic` values to identify the order sequences are concatenated.

---

<div class="post-metadata">

**Author:** ![ab73863](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/ab73863/32/11144_2.png) [@ab73863](https://discourse.nodered.org/u/ab73863)\
**Post date:** [22 January 2020 12:42 UTC](https://discourse.nodered.org/t/how-to-use-batch-node-with-concatenate-sequences-mode/20709/10 "2020-01-22T12:42:27Z")

</div>

@kuema,

As you have stated an actual use case as well a technical example of how to use the batch node in **concatenate sequence mode** is the missing in node red documentation. The brief section in node red doc mentions to use msg.topic to concatenate . I attempted the flow which is having two inputs to batch node and each input having a specific msg.topic name but it was not concatenating the two messages .

So I came to a conclusion that my fundamental understanding of concatenate sequence mode is either wrong or my implementation is wrong.

@Colin , thanks for your response.

Regards  
Arun

---

<div class="post-metadata">

**Author:** ![dceejay](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/dceejay/32/38_2.png) [@dceejay](https://discourse.nodered.org/u/dceejay)\
**Post date:** [23 January 2020 09:44 UTC](https://discourse.nodered.org/t/how-to-use-batch-node-with-concatenate-sequences-mode/20709/11 "2020-01-23T09:44:10Z")

</div>

Here are a couple of examples  
Note the second isn't just a sort (much too easy :-)... but takes the negative numbers into a group - (topic), likewise the positive - then rejoins the groups... in a sequence set by the topics...

```auto
[{"id":"5208ff70.44718","type":"inject","z":"e0631187.0034b","name":"","topic":"SEQ","payload":"[1,2,3,4,5]","payloadType":"json","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":140,"y":140,"wires":[["f631ec88.be849"]]},{"id":"f631ec88.be849","type":"split","z":"e0631187.0034b","name":"","splt":"\\n","spltType":"str","arraySplt":1,"arraySpltType":"len","stream":false,"addname":"","x":310,"y":140,"wires":[["4c952bd2.0c3ef4"]]},{"id":"4c952bd2.0c3ef4","type":"batch","z":"e0631187.0034b","name":"","mode":"concat","count":10,"overlap":0,"interval":10,"allowEmptySequence":false,"topics":[{"topic":"SEQ"},{"topic":"SEQ"}],"x":450,"y":140,"wires":[["b0910814.ba9308"]]},{"id":"b0910814.ba9308","type":"join","z":"e0631187.0034b","name":"","mode":"auto","build":"string","property":"payload","propertyType":"msg","key":"topic","joiner":"\\n","joinerType":"str","accumulate":"false","timeout":"","count":"","reduceRight":false,"x":590,"y":140,"wires":[["e22a7e3c.7a1d2"]]},{"id":"e22a7e3c.7a1d2","type":"debug","z":"e0631187.0034b","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","x":750,"y":140,"wires":[]},{"id":"5879f216.2ce0bc","type":"comment","z":"e0631187.0034b","name":"Duplicate","info":"","x":80,"y":100,"wires":[]},{"id":"92182451.05d258","type":"inject","z":"e0631187.0034b","name":"","topic":"SEQ","payload":"[1,-6,-8,7,2,-3]","payloadType":"json","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":140,"y":260,"wires":[["17bfb97.3315847"]]},{"id":"17bfb97.3315847","type":"split","z":"e0631187.0034b","name":"","splt":"\\n","spltType":"str","arraySplt":1,"arraySpltType":"len","stream":false,"addname":"","x":310,"y":260,"wires":[["bcf68114.86dad"]]},{"id":"37ac894a.6691e6","type":"comment","z":"e0631187.0034b","name":"Filter & Concat","info":"","x":100,"y":220,"wires":[]},{"id":"bcf68114.86dad","type":"switch","z":"e0631187.0034b","name":"","property":"payload","propertyType":"msg","rules":[{"t":"gt","v":"0","vt":"num"},{"t":"else"}],"checkall":"true","repair":true,"outputs":2,"x":370,"y":320,"wires":[["524fb754.ec6008"],["15bf3a07.977816"]]},{"id":"44a61da0.b3fa64","type":"comment","z":"e0631187.0034b","name":"↑ Duplicate SEQ","info":"","x":480,"y":180,"wires":[]},{"id":"524fb754.ec6008","type":"change","z":"e0631187.0034b","name":"Topic←POS","rules":[{"t":"set","p":"topic","pt":"msg","to":"POS","tot":"str"}],"action":"","property":"","from":"","to":"","reg":false,"x":530,"y":280,"wires":[["60d5ee4e.e9abd"]]},{"id":"15bf3a07.977816","type":"change","z":"e0631187.0034b","name":"Topic←NEG","rules":[{"t":"set","p":"topic","pt":"msg","to":"NEG","tot":"str"}],"action":"","property":"","from":"","to":"","reg":false,"x":530,"y":340,"wires":[["60d5ee4e.e9abd"]]},{"id":"60d5ee4e.e9abd","type":"batch","z":"e0631187.0034b","name":"","mode":"concat","count":10,"overlap":0,"interval":10,"allowEmptySequence":false,"topics":[{"topic":"NEG"},{"topic":"POS"}],"x":690,"y":320,"wires":[["3172cb41.204654"]]},{"id":"f18fb109.d9302","type":"debug","z":"e0631187.0034b","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","x":910,"y":260,"wires":[]},{"id":"3172cb41.204654","type":"join","z":"e0631187.0034b","name":"","mode":"auto","build":"string","property":"payload","propertyType":"msg","key":"topic","joiner":"\\n","joinerType":"str","accumulate":"false","timeout":"","count":"","reduceRight":false,"x":750,"y":260,"wires":[["f18fb109.d9302"]]},{"id":"bd630efb.7ec67","type":"comment","z":"e0631187.0034b","name":"↑ Order sequence: negative→positive","info":"","x":790,"y":360,"wires":[]},{"id":"182c0d29.62f153","type":"comment","z":"e0631187.0034b","name":"Filter pos/neg and make separate sequence↑ (but not a simple sort) ","info":"","x":300,"y":380,"wires":[]}]

```

---

<div class="post-metadata">

**Author:** ![ab73863](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/ab73863/32/11144_2.png) [@ab73863](https://discourse.nodered.org/u/ab73863)\
**Post date:** [23 January 2020 23:11 UTC](https://discourse.nodered.org/t/how-to-use-batch-node-with-concatenate-sequences-mode/20709/12 "2020-01-23T23:11:39Z")

</div>

> [@dceejay](#):
>
> [{"id":"5208ff70.44718","type":"inject","z":"e0631187.0034b","name":"","topic":"SEQ","payload":"[1,2,3,4,5]","payloadType":"json","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":140,"y":140,"wires":[["f631ec88.be849"]]},{"id":"f631ec88.be849","type":"split","z":"e0631187.0034b","name":"","splt":"\n","spltType":"str","arraySplt":1,"arraySpltType":"len","stream":false,"addname":"","x":310,"y":140,"wires":[["4c952bd2.0c3ef4"]]},{"id":"4c952bd2.0c3ef4","type":"batch","z":"e0631187.0034b","name":"","mode":"concat","count":10,"overlap":0,"interval":10,"allowEmptySequence":false,"topics":[{"topic":"SEQ"},{"topic":"SEQ"}],"x":450,"y":140,"wires":[["b0910814.ba9308"]]},{"id":"b0910814.ba9308","type":"join","z":"e0631187.0034b","name":"","mode":"auto","build":"string","property":"payload","propertyType":"msg","key":"topic","joiner":"\n","joinerType":"str","accumulate":"false","timeout":"","count":"","reduceRight":false,"x":590,"y":140,"wires":[["e22a7e3c.7a1d2"]]},{"id":"e22a7e3c.7a1d2","type":"debug","z":"e0631187.0034b","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","x":750,"y":140,"wires":},{"id":"5879f216.2ce0bc","type":"comment","z":"e0631187.0034b","name":"Duplicate","info":"","x":80,"y":100,"wires":},{"id":"92182451.05d258","type":"inject","z":"e0631187.0034b","name":"","topic":"SEQ","payload":"[1,-6,-8,7,2,-3]","payloadType":"json","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":140,"y":260,"wires":[["17bfb97.3315847"]]},{"id":"17bfb97.3315847","type":"split","z":"e0631187.0034b","name":"","splt":"\n","spltType":"str","arraySplt":1,"arraySpltType":"len","stream":false,"addname":"","x":310,"y":260,"wires":[["bcf68114.86dad"]]},{"id":"37ac894a.6691e6","type":"comment","z":"e0631187.0034b","name":"Filter & Concat","info":"","x":100,"y":220,"wires":},{"id":"bcf68114.86dad","type":"switch","z":"e0631187.0034b","name":"","property":"payload","propertyType":"msg","rules":[{"t":"gt","v":"0","vt":"num"},{"t":"else"}],"checkall":"true","repair":true,"outputs":2,"x":370,"y":320,"wires":[["524fb754.ec6008"],["15bf3a07.977816"]]},{"id":"44a61da0.b3fa64","type":"comment","z":"e0631187.0034b","name":"↑ Duplicate SEQ","info":"","x":480,"y":180,"wires":},{"id":"524fb754.ec6008","type":"change","z":"e0631187.0034b","name":"Topic←POS","rules":[{"t":"set","p":"topic","pt":"msg","to":"POS","tot":"str"}],"action":"","property":"","from":"","to":"","reg":false,"x":530,"y":280,"wires":[["60d5ee4e.e9abd"]]},{"id":"15bf3a07.977816","type":"change","z":"e0631187.0034b","name":"Topic←NEG","rules":[{"t":"set","p":"topic","pt":"msg","to":"NEG","tot":"str"}],"action":"","property":"","from":"","to":"","reg":false,"x":530,"y":340,"wires":[["60d5ee4e.e9abd"]]},{"id":"60d5ee4e.e9abd","type":"batch","z":"e0631187.0034b","name":"","mode":"concat","count":10,"overlap":0,"interval":10,"allowEmptySequence":false,"topics":[{"topic":"NEG"},{"topic":"POS"}],"x":690,"y":320,"wires":[["3172cb41.204654"]]},{"id":"f18fb109.d9302","type":"debug","z":"e0631187.0034b","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","x":910,"y":260,"wires":},{"id":"3172cb41.204654","type":"join","z":"e0631187.0034b","name":"","mode":"auto","build":"string","property":"payload","propertyType":"msg","key":"topic","joiner":"\n","joinerType":"str","accumulate":"false","timeout":"","count":"","reduceRight":false,"x":750,"y":260,"wires":[["f18fb109.d9302"]]},{"id":"bd630efb.7ec67","type":"comment","z":"e0631187.0034b","name":"↑ Order sequence: negative→positive","info":"","x":790,"y":360,"wires":},{"id":"182c0d29.62f153","type":"comment","z":"e0631187.0034b","name":"Filter pos/neg and make separate sequence↑ (but not a simple sort) ","info":"","x":300,"y":380,"wires":}]

Thanks a lot @dceejay. Perfect example.