[indexer-alt] Update obj_version indexes (#20869)

## Description 

Adds a new index to support bounded query.
I plan to merge this before I nuke the DB and start the race.

## Test plan 

How did you test the new or updated feature?

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## Release notes

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- [ ] Protocol: 
- [ ] Nodes (Validators and Full nodes): 
- [ ] gRPC:
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- [ ] CLI: 
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crates/sui-indexer-alt-schema/migrations/2024-10-30-142219_obj_versions/up.sql

@@ -12,3 +12,10 @@ CREATE TABLE IF NOT EXISTS obj_versions
 
 CREATE INDEX IF NOT EXISTS obj_versions_cp_sequence_number
 ON obj_versions (cp_sequence_number);
+
+-- This index is primarily used for querying the latest version of an object bounded by
+-- a view checkpoint number. Since a checkpoint can contain multiple versions of the
+-- same object, we need to sort by cp_sequence_number DESC and object_version DESC to
+-- get the latest version.
+CREATE INDEX IF NOT EXISTS obj_versions_id_cp_version
+ON obj_versions (object_id, cp_sequence_number DESC, object_version DESC)