Andrew Kyle Purtell created PHOENIX-8046:
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Summary: ALTER INDEX ... CONSISTENCY can desynchronize client
metadata caches
Key: PHOENIX-8046
URL: https://issues.apache.org/jira/browse/PHOENIX-8046
Project: Phoenix
Issue Type: Bug
Components: core
Affects Versions: 5.3.2
Reporter: Andrew Kyle Purtell
Assignee: Andrew Kyle Purtell
Fix For: 5.4.0, 5.3.3
Modifying an index's consistency model via {{ALTER INDEX ... CONSISTENCY}} can
silently desynchronize client metadata caches from the underlying schema. A
client connection can cache the parent data table without the altered index
attached. Subsequent write paths fail to maintain the index, and query planners
ignore it. Because the index metadata remains marked as {{{}ACTIVE{}}}, direct
reads against it yield missing or stale data.
Updating consistency modifies only the index header row, leaving the parent
table's {{PTable}} and timestamp unchanged. Immediately following the write,
the client invalidates its local cache by invoking
{{PMetaDataImpl.removeTable}} with the parent table's name and
{{{}LATEST_TIMESTAMP{}}}. Rather than dropping the parent entry, the client
cache attempts to rebuild the parent definition in place with the index
stripped out, preserving the original parent timestamp. Because this timestamp
still matches the unmodified server record, subsequent schema resolutions
conclude the client's cached parent is current. The client remains pinned to an
incomplete table definition. Explicitly resolving the index by name could
temporarily reattach it. However, a concurrent lookup of the parent table would
overwrite that repair with the earlier incorrect snapshot.
To guarantee cache coherence, the invalidation model requires two coordinated
changes:
* *Client Cache Invalidation:* When {{PMetaDataImpl.removeTable}} is invoked
with {{{}LATEST_TIMESTAMP{}}}, it must evict the parent table entry entirely.
Forcing an eviction ensures the next schema resolution refetches the complete
parent definition from the server, preventing stale in-memory snapshots from
perpetuating partial states. When an explicit timestamp is supplied, the
existing selective removal behavior is preserved.
* *Server Cache Coherence:* The ALTER path must proactively purge the parent
data table from the server side metadata cache. Because the server caches data
tables alongside their associated index descriptors, evicting the parent
prevents the server from serving stale descriptors to subsequent client lookups.
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