OCI Object Storage Text Embedding (Rust)

Rust port of the Python oci_object_storage_embedding example.

Lists markdown files from an Oracle Cloud Infrastructure (OCI) Object Storage bucket, chunks each file, embeds the chunks, and stores them in Postgres/pgvector — then serves similarity search.

Parallel to the Python example

Concern	Python	Rust (this example)
Source	`oci_object_storage.list_objects` (`oci` SDK)	`cocoindex::oci_object_storage::list_objects` (native REST)
Auth	`oci.config.from_file` + `ObjectStorageClient`	`OciClient::connect` reads `~/.oci/config`, signs requests
Per-file compute	`@coco.fn(memo=True) process_file`	`#[cocoindex::function(memo)] process_file`
Chunking	`RecursiveSplitter` (markdown, 2000/500)	`RecursiveSplitter` (markdown, 2000/500)
Embeddings	`sentence-transformers/all-MiniLM-L6-v2`	`fastembed` `AllMiniLML6V2` (same model, 384-dim)
Target	`postgres.mount_table_target` + pgvector	`postgres::mount_table_target` + `declare_vector_index`

There is no official Oracle SDK for Rust, so the connector talks to the Object Storage REST API directly and implements OCI's RSA-SHA256 HTTP Signature signing (the same ~/.oci/config API-key auth the Python SDK uses). The source is one-shot (no live mode); the listed OciFile is a serializable metadata item, so per-file memoization handles edits and the managed TableTarget reconciles away rows for deleted objects.

Prerequisites

An ~/.oci/config profile with an unencrypted API key. Generate one in the OCI console (Profile → API Keys → Add API Key) and download the config snippet and private key. It looks like:
ini
```
[DEFAULT]
user=ocid1.user.oc1..aaaa
fingerprint=aa:bb:cc:...
tenancy=ocid1.tenancy.oc1..bbbb
region=us-ashburn-1
key_file=~/.oci/oci_api_key.pem
```
A pgvector-enabled Postgres.

Run

bash

export OCI_NAMESPACE=my-namespace        # your Object Storage namespace
export OCI_BUCKET=my-bucket
export OCI_PREFIX=docs/                   # optional
# Optional overrides (defaults: ~/.oci/config and the DEFAULT profile):
# export OCI_CONFIG_FILE=~/.oci/config
# export OCI_PROFILE=DEFAULT
export POSTGRES_URL=postgres://cocoindex:cocoindex@localhost/cocoindex   # pgvector-enabled

cargo run -- index                  # list oci://$OCI_NAMESPACE/$OCI_BUCKET/$OCI_PREFIX/**.md -> embed -> Postgres
cargo run -- query "your query"     # cosine similarity search

Not yet supported

Live bucket watching (OCI Events / Streaming) — deferred until the Rust live source API is generalized, matching the Amazon S3 example.
Pass-phrase-encrypted private keys — use an unencrypted API key.