discord9 28697c9e55 feat(datanode): execute nested MergeScan plans on the datanode (#9206) ...

* feat(datanode): execute nested MergeScan plans on the datanode

Give a datanode the ability to decode and execute a plan whose MergeScan
carries a nested plan (e.g. an inner MergeScan over a build table), so a
distributed sub-plan pushed to a datanode can itself fan out to other
datanodes. This is the execution/codec capability only; it is not wired
to any user-facing switch and produces no plan by itself.

Codec (src/query/src/query_engine/default_serializer.rs):
- MergeScanAwareSerializer keeps the request's SessionState and the
  engine catalog manager, and decodes a MergeScan payload's tables by
  (catalog, schema, table) name through the engine catalog rather than
  the region-aware request catalog list (which binds every table to the
  request's region and breaks on mismatched columns).

Datanode (src/datanode):
- New DatanodeRegionQueryHandler (region_query.rs) serves region queries
  for the MergeScan nodes of a received plan, resolving region leaders
  via PartitionRuleManager and dispatching to peer datanodes.
- Wire KvBackendCatalogManager + PartitionRuleManager + NodeClients into
  the datanode's catalog/cache registry (with_dist_planner stays false:
  a datanode never rewrites its own plan).

Bug fixes uncovered while wiring this up:
- cache registry: register the table/table_info/table_name/table_route/
  partition_info caches the datanode's catalog manager and partition
  rule manager require (previously missing -> panic on lookup).
- default_serializer: decode_sub_plan bridge no longer drives a future
  on a current-thread runtime from within another executor (spawn a
  dedicated thread + runtime when not on a multi-thread runtime).

Tested by query_engine::default_serializer unit tests: nested MergeScan
round-trip and engine-catalog resolution with mismatched column names.
No user-facing behavior change.

Signed-off-by: discord9 <55937128+discord9@users.noreply.github.com>

* fix(query): keep GreptimeDB function bindings after rebuilding decode state

SessionStateBuilder::new_from_existing collects the function registry
(HashMap) into a Vec and build() re-registers each entry; register_udf
registers aliases before the function's own name and the Vec order is
unstable. Rebuilding the session state to install MergeScanAwareSerializer
after the GreptimeDB functions were registered could therefore rebind a
name/alias (e.g. date_format, an alias of DataFusion's to_char) back to
the built-in function. This path runs for every decoded plan, not only
nested MergeScan ones.

Extract the GreptimeDB function registration into register_greptime_functions
and re-apply it after the final build of both the top-level decode state and
the MergeScan payload state. Add regression tests asserting date_format stays
bound to the GreptimeDB implementation on both paths.

Signed-off-by: discord9 <55937128+discord9@users.noreply.github.com>

* fix(datanode): address review on nested MergeScan capability

Three follow-ups from review of the nested MergeScan execution capability:

1. Layer the datanode caches (P2b). table_cache derives from
   table_info_cache + table_name_cache, and partition_info_cache derives
   from table_route_cache, but they were all registered in a single flat
   CacheRegistry whose invalidate() runs concurrently with no ordering.
   A derived cache could be invalidated and refilled from a base cache
   that had not been invalidated yet, leaving stale metadata. Build the
   base caches and the derived caches as separate layers of a
   LayeredCacheRegistry (reusing the existing layering mechanism) so base
   caches finish invalidating before derived ones. Both the production
   path (cmd) and the test scaffolding now build the same layered
   registry; the flat build_datanode_cache_registry is removed.

2. Don't let a nested MergeScan's internal region query compete for the
   concurrency permit (P2a). An outer query holds its permit until its
   stream is fully consumed, and a nested MergeScan makes the datanode
   issue region queries to peer datanodes as execution stages of that
   same query. If such an inner stage also took a permit, the outer query
   waiting on it would deadlock against its own held permit (or time out
   when max_concurrent_queries > 0). Mark inner DN->DN region queries as
   internal stages: QueryRequest gains an  flag carried over
   the wire in the request header's query_context extensions (reserved
   key, not injectable via hints), and the region server skips acquiring
   a concurrency permit for internal-stage requests on both acquire
   sites. Outer queries still acquire normally.

3. Add an end-to-end capability test
   (tests-integration/.../nested_merge_scan_capability_test.rs): hand-build
   Join(<local probe region>, MergeScan(build regions on both datanodes))
   with mismatched column names and duplicate build keys, ship it to a
   datanode over a real TCP Flight endpoint, consume the stream fully and
   compare the row multiset against the frontend's reference join result,
   assert a real cross-datanode DoGet via an RPC counter, and assert an
   inner region failure fails the whole query. Also migrate the
   with_real_datanode_grpc_addr + DatanodeRpcStats test scaffolding.

Signed-off-by: discord9 <55937128+discord9@users.noreply.github.com>

* fix(query): adapt date_format regression test to the updated DataFusion fork

ScalarUDFImpl's trait bounds changed so its impl can no longer be
downcast via as_any(); assert the function equals the GreptimeDB
implementation instead, which to_char can never satisfy.

Signed-off-by: discord9 <55937128+discord9@users.noreply.github.com>

* test(datanode): cover the internal stage under the concurrency limit

Add an end-to-end regression test for the nested MergeScan capability
under max_concurrent_queries = 1: both datanodes' only permit is held by
the outer queries' streams while their inner MergeScans fetch the build
regions from the same datanodes over real Flight connections. The result
consumption is bounded by a timeout, so a broken link anywhere in the
chain (marking the inner request internal, carrying the marker in the
request header, honoring it at the receiving acquire sites) fails the
test instead of deadlocking.

Also add a minimal with_datanode_options_override hook to the cluster
builder, and fix the test module doc: the outer request is handed to
RegionServer::handle_remote_read in process; only the inner region
queries go over the wire.

Signed-off-by: discord9 <55937128+discord9@users.noreply.github.com>

* test(datanode): cover cold route loads under unrelated invalidations

The table route cache uses InitStrategy::VersionChecked, whose version
counter belongs to the whole CacheContainer rather than to a single
table: any TableId invalidation bumps the shared version, so a cold
load of one table's route retries when an unrelated table is
invalidated concurrently. Document this as a known limitation on the
region query handler, and pin the behavior with an integration test:
run the nested plans while a background task invalidates an unrelated
table id on every datanode, assert the results still match the expected
multiset (retries only add work, they never return a stale route), and
report the observed load amplification via the cache miss counter
(2 loads without invalidations, 8 over three runs with 24 unrelated
invalidations in this run). Also expose the datanode cache registries
on the test cluster so a test can drive the local invalidation path
that the heartbeat handler drives after a metasrv broadcast.

Signed-off-by: discord9 <55937128+discord9@users.noreply.github.com>

* docs(query): trim nested plan decoder commentary

Signed-off-by: discord9 <55937128+discord9@users.noreply.github.com>

* refactor: remove redundant nested scan support plumbing

Signed-off-by: discord9 <55937128+discord9@users.noreply.github.com>

* fix(query): decode nested MergeScan payloads asynchronously

Signed-off-by: discord9 <55937128+discord9@users.noreply.github.com>

* test(query): avoid unnecessary extension name allocation

Signed-off-by: discord9 <55937128+discord9@users.noreply.github.com>

* fix(query): retain extension decoding for manual session states

Signed-off-by: discord9 <55937128+discord9@users.noreply.github.com>

* refactor(datanode): keep nested scan query admission unchanged

Signed-off-by: discord9 <55937128+discord9@users.noreply.github.com>

* fix(datanode): honor query handler factories and trim nested scan fixtures

Signed-off-by: discord9 <55937128+discord9@users.noreply.github.com>

* fix(datanode): retain required cache error import

Signed-off-by: discord9 <55937128+discord9@users.noreply.github.com>

* refactor(query): reuse registered state for nested scan decoding

Signed-off-by: discord9 <55937128+discord9@users.noreply.github.com>

* test(query): verify payload information schema table functions

Signed-off-by: discord9 <55937128+discord9@users.noreply.github.com>

* test(query): retain nested scan runtime and cold-route guards

Signed-off-by: discord9 <55937128+discord9@users.noreply.github.com>

* refactor(query): address nested scan review feedback

Signed-off-by: discord9 <55937128+discord9@users.noreply.github.com>

* fix(session): preserve read preference across region query hops

Signed-off-by: discord9 <55937128+discord9@users.noreply.github.com>

* test(session): verify strict context rejection at Flow ingress

Signed-off-by: discord9 <55937128+discord9@users.noreply.github.com>

* test(query): remove redundant serializer error case

Signed-off-by: discord9 <55937128+discord9@users.noreply.github.com>

---------

Signed-off-by: discord9 <55937128+discord9@users.noreply.github.com>

2026-10-10 06:49:38 +00:00

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