[Enhancement] Route range-distribution OLAP tables by per-index distribution expressions (backport #74753)

[mergify]

Why I'm doing:

Range-distribution (shared-data) tables route rows to tablets by per-tablet boundaries stored in sort-key space, but the OLAP table sink could only carry a single partition-level distribution-column set. It therefore could not route different rows to materialized indexes that live in different key spaces. This is the missing sink piece for two future features — the K-tablet shadow-index rewrite job (key-column schema change) and range-distribution rollup — both of which need a base index and a new-key index to coexist in one partition and be routed independently.

What I'm doing:

Add per-index distribution routing to the sink:

• thrift: new TOlapTableIndexSchema.distributed_exprs (field 9) carrying per-index routing expression trees, evaluated at the sink sender. Sender-only: POlapTableIndexSchema (proto) is unchanged, so remote write channels never route by it.
• FE: OlapTableSink.createSchema fills distributed_exprs for range-distribution tables with slot-refs over each index's range sort-key columns, gated to the OLAP write-sink path (dictionary / non-write callers do not emit it). For today's base-only range tables this resolves to exactly the columns the partition-level path already used, so routing is behavior-preserving. Also adds an optional targetWriteIndexId filter (write only one index; schema, partition and loaded-index lists stay 1:1 by meta id).
• BE: OlapTableSchemaParam parses distributed_exprs into per-index ExprContexts (prepare/open/close lifecycle); the range sink sender evaluates them once per chunk per index and routes via RangeRouter. RangeRouter::init validates routing-key types against the boundary types; a new route_chunk_rows overload routes from pre-evaluated columns; an empty distributed_exprs (K=1) routes to the single tablet. When an index has no distributed_exprs, routing falls back to the partition-level path unchanged.

No version gate is needed: StarRocks upgrades BE/CN before FE, so a newly-upgraded FE (the only one that emits the field) never runs against a BE that does not understand it, and an old FE never emits it. Non-range tables and any unset field are byte-for-byte unchanged. This is prerequisite-only: the new capability is dormant for existing tables and consumed by future work.

What type of PR is this:

• BugFix
• Feature
• Enhancement
• Refactor
• UT
• Doc
• Tool

Does this PR entail a change in behavior?

• Yes, this PR will result in a change in behavior.
• No, this PR will not result in a change in behavior.

Checklist:

• I have added test cases for my bug fix or my new feature
• This pr needs user documentation (for new or modified features or behaviors)
  • I have added documentation for my new feature or new function
  • This pr needs auto generate documentation
• This is a backport pr

Bugfix cherry-pick branch check:

• I have checked the version labels which the pr will be auto-backported to the target branch
  • 4.1
  • 4.0
  • 3.5

🤖 Generated with Claude Code

---

This is an automatic backport of pull request #74753 done by Mergify.

[mergify]

Cherry-pick of 60a751b has failed:

On branch mergify/bp/branch-4.1/pr-74753
Your branch is up to date with 'origin/branch-4.1'.

You are currently cherry-picking commit 60a751bdaa.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   be/src/exec/range_router.cpp
	modified:   be/src/exec/range_router.h
	modified:   be/src/exec/range_tablet_sink_sender.cpp
	modified:   be/src/exec/range_tablet_sink_sender.h
	modified:   be/src/exec/tablet_info.h
	modified:   be/test/exec/range_router_test.cpp
	modified:   be/test/exec/tablet_info_test.cpp
	modified:   fe/fe-core/src/main/java/com/starrocks/planner/DictionaryCacheSink.java
	modified:   fe/fe-core/src/main/java/com/starrocks/planner/OlapTableSink.java
	modified:   fe/fe-core/src/main/java/com/starrocks/service/FrontendServiceImpl.java
	modified:   fe/fe-core/src/test/java/com/starrocks/planner/OlapTableSinkTest.java
	modified:   fe/fe-core/src/test/java/com/starrocks/planner/OlapTableSinkTest2.java
	modified:   gensrc/thrift/Descriptors.thrift

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   be/src/exec/tablet_info.cpp
	both modified:   be/test/exec/tablet_sink_sender_range_test.cpp

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[mergify]

@mergify[bot]: Backport conflict, please reslove the conflict and resubmit the pr

[xiangguangyxg]

Resolved the backport conflict and force-pushed the clean cherry-pick (5463a84).

Cause: branch-4.1 predates two main-only refactors that the cherry-pick of 60a751b collided with:

1. be/src/exec/tablet_info.cpp — main renamed the static expr lifecycle helpers Expr::prepare/open/close → ExprExecutor::prepare/open/close. 4.1 still uses Expr::. The P1a hunk that adds the per-index distributed_expr_ctxs prepare/open/close loop landed right next to those renamed calls, so the context conflicted.
2. be/test/exec/tablet_sink_sender_range_test.cpp — on main this test lives under be/test/exec/data_sinks/ and uses the post-reorg header paths (types/type_descriptor.h, types/datum.h, base/testutil/assert.h). 4.1 has it flat under be/test/exec/ with the older paths (runtime/types.h, column/datum.h, testutil/assert.h), producing a rename + include conflict.

Resolution (the only two changed regions, verified against b122aae):

• tablet_info.cpp: kept 4.1's Expr::prepare/open/close API and added the P1a per-index loop on top — no ExprExecutor:: references remain.
• test includes: mapped to 4.1's header layout (runtime/types.h for TypeDescriptor, column/datum.h already present for Datum); added gen_cpp/descriptors.pb.h, runtime/descriptor_helper.h, runtime/exec_env.h, runtime/runtime_state.h. The test body is byte-identical to main.

Confirmed all P1a dependencies exist on 4.1 (MetaUtils.getRangeDistributionColumns(table, indexMetaId), ExprToThrift.treesToThrift, OlapTable.isRangeDistribution, getLatestMaterializedIndices(IndexExtState)) and that TOlapTableIndexSchema thrift field 9 is free on 4.1. Leaving the rest of the cherry-pick to CI for the full BE/FE compile.