Carl Yeksigian updated CASSANDRA-12268:
    Resolution: Fixed
        Status: Resolved  (was: Patch Available)

The tests looked like they were unrelated (all passed locally).

Committed as 

> Make MV Index creation robust for wide referent rows
> ----------------------------------------------------
>                 Key: CASSANDRA-12268
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-12268
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Jonathan Shook
>            Assignee: Carl Yeksigian
>             Fix For: 3.0.x, 3.x
>         Attachments: 12268.py
> When creating an index for a materialized view for extant data, heap pressure 
> is very dependent on the cardinality of of rows associated with each index 
> value. With the way that per-index value rows are created within the index, 
> this can cause unbounded heap pressure, which can cause OOM. This appears to 
> be a side-effect of how each index row is applied atomically as with batches.
> The commit logs can accumulate enough during the process to prevent the node 
> from being restarted. Given that this occurs during global index creation, 
> this can happen on multiple nodes, making stable recovery of a node set 
> difficult, as co-replicas become unavailable to assist in back-filling data 
> from commitlogs.
> While it is understandable that you want to avoid having relatively wide rows 
>  even in materialized views, this represents a particularly difficult 
> scenario for triage.
> The basic recommendation for improving this is to sub-group the index 
> creation into smaller chunks internally, providing a maximal bound against 
> the heap pressure when it is needed.

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