Add overlapping fields (index-alias for index state management)

[vagimeli]

Description

Address feedback about documenting overlapping fields

Issues Resolved

#4336

Version

Backport 2.15

Frontend features

If you're submitting documentation for an OpenSearch Dashboards feature, add a video that shows how a user will interact with the UI step by step. A voiceover is optional.

Checklist

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[vagimeli]

Technical reviewer: Please confirm this example is relevant to an OpenSearch user and addresses the following user feedback: Undocumented behavior for when two indexes with overlapping field names are associated with the same alias. What happens when these are different types? There appears to be some kind of implicit casting that occurs. I tested the example using Dev Tools. If another example is more appropriate, please replace the draft example with your example. Thank you.

[bowenlan-amzn]

Any problem case they provided? I'm not sure what is this implicit casting they are refering to.

[vagimeli]

Quote reply

@bowenlan-amzn This is feedback from a user via the documentation comments. No other info provided. I found this info, but don't know if it's related https://forum.opensearch.org/t/help-with-text-field-mapping-and-implicit-conversion-of-integer-and-boolean-to-text/16226. Should we close this and open a new PR when we have more details?

[vagimeli]

@bowenlan-amzn Would you or other index management team member be available to technical review this PR? It addresses community feedback about Undocumented behavior for when two indexes with overlapping field names are associated with the same alias. What happens when these are different types? There appears to be some kind of implicit casting that occurs. Thank you.

[bowenlan-amzn]

@vagimeli commented on Jul 11, 2024, 11:16 PM GMT+8:

@bowenlan-amzn Would you or other index management team member be available to technical review this PR? It addresses community feedback about Undocumented behavior for when two indexes with overlapping field names are associated with the same alias. What happens when these are different types? There appears to be some kind of implicit casting that occurs. Thank you.

I'm not sure there's implicit casting. I suggest we wait for an example showing this is happening. I did a very simple experiment by creating 2 indexes like you wrote in the documentation. Then index some data and do a simple search, I don't see any casting.
There maybe some circumstances that some query can do the casting behind the scene but I am not aware.

[vagimeli]

Suggested change

	When querying an alias that points to multiple indexes with overlapping field names of different data types, OpenSearch attempts to merge the data from these indexes. However, due to the conflicting data types, OpenSearch performs implicit casting or type conversion on the field values to reconcile the differences.
	When querying an alias that points to multiple indexes with overlapping field names of different data types, OpenSearch attempts to merge the data from these indexes.

[vagimeli]

@vagimeli commented on Jul 11, 2024, 11:16 PM GMT+8:

@bowenlan-amzn Would you or other index management team member be available to technical review this PR? It addresses community feedback about Undocumented behavior for when two indexes with overlapping field names are associated with the same alias. What happens when these are different types? There appears to be some kind of implicit casting that occurs. Thank you.

I'm not sure there's implicit casting. I suggest we wait for an example showing this is happening. I did a very simple experiment by creating 2 indexes like you wrote in the documentation. Then index some data and do a simple search, I don't see any casting. There maybe some circumstances that some query can do the casting behind the scene but I am not aware.

@bowenlan-amzn I'm closing this PR. This was to address community feedback. When the issue arises, the dev team can create open a new PR. Thanks for your help.