# How to allow in-place upgrade of persistent query with variable underlying data
**URL:** https://forum.confluent.io/t/how-to-allow-in-place-upgrade-of-persistent-query-with-variable-underlying-data/8949
**Category:** ksqlDB
**Created:** [27 October 2023 17:54 UTC](https://forum.confluent.io/t/how-to-allow-in-place-upgrade-of-persistent-query-with-variable-underlying-data/8949 "2023-10-27T17:54:47Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@akos](https://forum.confluent.io/u/akos)
#### Post date: [27 October 2023 17:54 UTC](https://forum.confluent.io/t/how-to-allow-in-place-upgrade-of-persistent-query-with-variable-underlying-data/8949/1 "2023-10-27T17:54:47Z")
Is there a solution or workaround to evolving a ksql stream in-place (`CREATE OR REPLACE`) that has a json object with variable fields?
eg: if the incoming topic has a field like:
```auto
{
"metadata": {
"fieldA": "string val",
"fieldB": 123
}
}
```
Later, we get decide that metadata can have a new field `fieldC` that is a string value.
From what I can tell `STRUCT` is not a good fit here because it doesn’t allow in-place update where you add a new field to the struct 😞🫠
And `MAP` is not quite the best either because it requires a consistent value type (eg: `fieldB`` would end up getting emitted by our stream as a `VARCHAR`rather than an`INT`) 😞
I’ve been playing around with the various JSON scalar functions but nothing seems to allow me to emit the values in their original types, while allowing future in-place replacements
---
### Author:  [@system](https://forum.confluent.io/u/system)
#### Post date: [26 November 2023 17:55 UTC](https://forum.confluent.io/t/how-to-allow-in-place-upgrade-of-persistent-query-with-variable-underlying-data/8949/2 "2023-11-26T17:55:15Z")
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