mchades commented on code in PR #9173:
URL: https://github.com/apache/gravitino/pull/9173#discussion_r2596939589
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docs/lakehouse-generic-catalog.md:
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+---
+title: "Generic Lakehouse Catalog"
+slug: /lakehouse-generic-catalog
+keywords:
+ - lakehouse
+ - lance
+ - metadata
+ - generic catalog
+ - file system
+license: "This software is licensed under the Apache License version 2."
+---
+
+import Tabs from '@theme/Tabs';
+import TabItem from '@theme/TabItem';
+
+## Overview
+
+The Generic Lakehouse Catalog is a Gravitino catalog implementation designed
to seamlessly integrate with lakehouse storage systems built on file
system-based architectures. This catalog enables unified metadata management
for lakehouse tables stored on various storage backends, providing a consistent
interface for data discovery, governance, and access control.
+
+### What is a Lakehouse?
+
+A lakehouse combines the best features of data lakes and data warehouses:
+
+- **Data Lake Benefits**:
+ - Low-cost storage for massive volumes of raw data
+ - Support for diverse data formats (structured, semi-structured,
unstructured)
+ - Decoupled storage and compute for flexible scaling
+
+- **Data Warehouse Benefits**:
+ - ACID transactions for data consistency
+ - Schema enforcement and evolution
+ - High-performance analytical queries
+ - Time travel and versioning
+
+### Supported Storage Systems
+
+The catalog works with lakehouse systems built on top of:
+
+**Storage Backends:**
+- **Object Stores:** Amazon S3, Azure Blob Storage, Google Cloud Storage, MinIO
+- **Distributed File Systems:** HDFS, Apache Ozone
+- **Local File Systems:** For development and testing
+
+**Lakehouse Formats:**
+- **Lance** ✅ (We only support Lance format fully at present)
+
+:::info Current Support Status
+While the architecture is designed to support various lakehouse formats,
Gravitino currently provides **native production support only for Lance-based
lakehouse systems** with comprehensive testing and optimization.
+:::
+
+### Why Use Generic Lakehouse Catalog?
+
+1. **Unified Metadata Management**: Single source of truth for table metadata
across multiple storage backends
+2. **Multi-Format Support**: Extensible architecture to support various
lakehouse table formats
+3. **Storage Flexibility**: Work with any file system - local, HDFS, or cloud
object stores
+4. **Gravitino Integration**: Leverage Gravitino's access control, lineage
tracking, and data discovery
+5. **Easy Migration**: Register existing lakehouse tables without data movement
+
+### System Requirements
+
+**Storage Requirements:**
+- Lakehouse storage system must support standard file system operations:
+ - Directory listing and navigation
+ - File reading and writing with atomic operations
+ - File deletion and renaming
+ - Path-based access control (optional but recommended)
+
+**Gravitino Requirements:**
+- Gravitino server version 1.1.0 or later
+- Configured metalake for catalog creation
+- Appropriate permissions for catalog management
+
+**Network Requirements:**
+- Network connectivity between Gravitino server and storage backend
+- For cloud storage: Internet access and valid credentials
+- For HDFS: Proper Hadoop configuration and network access
+
+## Catalog Management
+
+### Capabilities
+
+The Generic Lakehouse Catalog provides comprehensive relational metadata
management capabilities equivalent to standard relational catalogs:
+
+**Supported Operations:**
+- ✅ Create, read, update, and delete catalogs
+- ✅ List all catalogs in a metalake
+- ✅ Manage catalog properties and metadata
+- ✅ Set and modify catalog locations
+- ✅ Configure storage backend credentials
+
+For detailed information on available operations, see [Manage Relational
Metadata Using Gravitino](./manage-relational-metadata-using-gravitino.md).
+
+### Properties
+
+#### Required Properties
+
+| Property | Description | Example
| Required |
Review Comment:
should add `Since Version` column?
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docs/lakehouse-generic-catalog.md:
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Review Comment:
you should also update the doc
https://github.com/apache/gravitino/blob/main/docs/manage-relational-metadata-using-gravitino.md
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docs/lance-rest-service.md:
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+---
+title: "Lance REST service"
+slug: /lance-rest-service
+keywords:
+ - Lance REST
+ - Lance datasets
+ - REST API
+license: "This software is licensed under the Apache License version 2."
+---
+
+import Tabs from '@theme/Tabs';
+import TabItem from '@theme/TabItem';
+
+## Overview
+
+The Lance REST service provides a RESTful interface for managing Lance
datasets through HTTP endpoints. Introduced in Gravitino version 1.1.0, this
service enables seamless interaction with Lance datasets for data operations
and metadata management.
+
+The service implements the [Lance REST API
specification](https://editor-next.swagger.io/?url=https://raw.githubusercontent.com/lancedb/lance-namespace/refs/heads/main/docs/src/rest.yaml).
For detailed specification documentation, see the [official Lance REST
documentation](https://lance.org/format/namespace/impls/rest/).
+
+### What is Lance?
+
+[Lance](https://lancedb.github.io/lance/) is a modern columnar data format
designed for AI/ML workloads. It provides:
+
+- **High-performance vector search**: Native support for similarity search on
high-dimensional embeddings
+- **Columnar storage**: Optimized for analytical queries and machine learning
pipelines
+- **Fast random access**: Efficient row-level operations unlike traditional
columnar formats
+- **Version control**: Built-in dataset versioning and time-travel capabilities
+- **Incremental updates**: Append and update data without full rewrites
+
+### Architecture
+
+The Lance REST service acts as a bridge between Lance datasets and
applications:
+
+```
+┌─────────────────┐
+│ Applications │
+│ (Python/Java) │
+└────────┬────────┘
+ │ HTTP/REST
+ ▼
+┌─────────────────┐
+│ Lance REST │◄──── Gravitino Metalake
+│ Service │ (Metadata Backend)
+└────────┬────────┘
+ │ File System Operations
+ ▼
+┌─────────────────┐
+│ Lance Datasets │
+│ (S3/HDFS/Local) │
+└─────────────────┘
+```
+
+**Key Features:**
+- Full compliance with Lance REST API specification
+- Can run standalone or integrated with Gravitino server
+- Support for namespace and table management
+- Index creation and management capabilities
+- Metadata stored in Gravitino for unified governance
+
+## Supported Operations
+
+The Lance REST service provides comprehensive support for namespace
management, table management, and index operations. The table below lists all
supported operations:
+
+| Operation | Description
| HTTP Method | Endpoint Pattern | Since Version |
+|-------------------|-------------------------------------------------------------------|-------------|-------------------------------------|---------------|
+| CreateNamespace | Create a new Lance namespace
| POST | `/lance/v1/namespace/{id}/create` | 1.1.0 |
+| ListNamespaces | List all namespaces under a parent namespace
| GET | `/lance/v1/namespace/{parent}/list` | 1.1.0 |
+| DescribeNamespace | Retrieve detailed information about a specific namespace
| POST | `/lance/v1/namespace/{id}/describe` | 1.1.0 |
+| DropNamespace | Delete a namespace
| POST | `/lance/v1/namespace/{id}/drop` | 1.1.0 |
+| NamespaceExists | Check whether a namespace exists
| POST | `/lance/v1/namespace/{id}/exists` | 1.1.0 |
+| ListTables | List all tables in a namespace
| GET | `/lance/v1/table/{namespace}/list` | 1.1.0 |
+| CreateTable | Create a new table in a namespace
| POST | `/lance/v1/table/{id}/create` | 1.1.0 |
+| DropTable | Delete a table including both metadata and data
| POST | `/lance/v1/table/{id}/drop` | 1.1.0 |
+| TableExists | Check whether a table exists
| POST | `/lance/v1/table/{id}/exists` | 1.1.0 |
+| RegisterTable | Register an existing Lance table to a namespace
| POST | `/lance/v1/table/{id}/register` | 1.1.0 |
+| DeregisterTable | Unregister a table from a namespace (metadata only, data
remains) | POST | `/lance/v1/table/{id}/deregister` | 1.1.0 |
+
+### Operation Details
+
+#### Namespace Operations
+
+**CreateNamespace** supports three modes:
+- `create`: Fails if namespace already exists
+- `exist_ok`: Succeeds even if namespace exists
+- `overwrite`: Replaces existing namespace
+
+**DropNamespace** behavior:
+- Recursively deletes all child namespaces and tables
+- Deletes both metadata and Lance data files
+- Operation is irreversible
+
+#### Table Operations
+
+**RegisterTable vs CreateTable**:
+- **RegisterTable**: Links existing Lance datasets into Gravitino catalog
without data movement
+- **CreateTable**: Creates new Lance table with schema and writes data files
+
+**DropTable vs DeregisterTable**:
+- **DropTable**: Permanently deletes metadata and data files from storage
+- **DeregisterTable**: Removes metadata from Gravitino but preserves Lance
data files
+
+:::note
+Index deletion is not supported in version 1.1.0.
+:::
+
+## Deployment
+
+### Running with Gravitino Server
+
+To enable the Lance REST service within Gravitino server, configure the
following properties in your Gravitino configuration file:
+
+| Configuration Property | Description
| Default Value |
Required | Since Version |
+|-------------------------------------------|------------------------------------------------------------------------------|-------------------------|----------|---------------|
+| `gravitino.auxService.names` | Auxiliary services to run.
Include `lance-rest` to enable Lance REST service | iceberg-rest,lance-rest |
Yes | 0.2.0 |
+| `gravitino.lance-rest.classpath` | Classpath for Lance REST
service, relative to Gravitino home directory | lance-rest-server/libs |
Yes | 1.1.0 |
+| `gravitino.lance-rest.httpPort` | Port number for Lance REST
service | 9101 |
Yes | 1.1.0 |
+| `gravitino.lance-rest.host` | Hostname for Lance REST service
| 0.0.0.0 | Yes
| 1.1.0 |
+| `gravitino.lance-rest.namespace-backend` | Namespace metadata backend
(currently only `gravitino` is supported) | gravitino |
Yes | 1.1.0 |
+| `gravitino.lance-rest.gravitino-uri` | Gravitino server URI (required
when namespace-backend is `gravitino`) | http://localhost:8090 | Yes
| 1.1.0 |
+| `gravitino.lance-rest.gravitino-metalake` | Gravitino metalake name
(required when namespace-backend is `gravitino`) | (none)
| Yes | 1.1.0 |
+
+**Example Configuration:**
+
+```properties
+gravitino.auxService.names = lance-rest
+gravitino.lance-rest.httpPort = 9101
+gravitino.lance-rest.host = 0.0.0.0
+gravitino.lance-rest.namespace-backend = gravitino
+gravitino.lance-rest.gravitino.uri = http://localhost:8090
+gravitino.lance-rest.gravitino.metalake-name = my_metalake
+```
+
+### Running Standalone
+
+To run Lance REST service independently without Gravitino server:
+
+```shell
+{GRAVITINO_HOME}/bin/gravitino-lance-rest-server.sh start
+```
+
+Configure the service by editing `gravitino-lance-rest-server.conf` or passing
command-line arguments:
+
+| Configuration Property | Description
| Default Value | Required | Since Version |
+|------------------------------------------------|-----------------------------|-----------------------|----------|---------------|
+| `gravitino.lance-rest.namespace-backend` | Namespace metadata backend
| gravitino | Yes | 1.1.0 |
+| `gravitino.lance-rest.gravitino.uri` | Gravitino server URI
| http://localhost:8090 | Yes | 1.1.0 |
+| `gravitino.lance-rest.gravitino.metalake-name` | Gravitino metalake name
| (none) | Yes | 1.1.0 |
+| `gravitino.lance-rest.httpPort` | Service port number
| 9101 | No | 1.1.0 |
+| `gravitino.lance-rest.host` | Service hostname
| 0.0.0.0 | No | 1.1.0 |
+
+:::tip
+In most cases, you only need to configure
`gravitino.lance-rest.gravitino.metalake-name`. Other properties can use their
default values.
+:::
+
+## Usage Guidelines
+
+When using Lance REST service with Gravitino backend, keep the following
considerations in mind:
+
+### Prerequisites
+- A running Gravitino server with a created metalake
+- A generic-lakehouse catalog created in Gravitino metalake
+
+### Namespace Hierarchy
+Gravitino follows a three-level hierarchy: **catalog → schema → table**. When
creating namespaces or tables:
+
+1. **Parent must exist:** Before creating `lance_catalog/schema`, ensure
`lance_catalog` catalog exists in Gravitino metalake
+2. **Two-level limit:** You can create `lance_catalog/schema`, but **not**
`lance_catalog/schema/sub_schema`
+3. **Table placement:** Tables can only be created under
`lance_catalog/schema`, not at catalog level
+
+**Example Hierarchy:**
+```
+metalake
+└── lance_catalog (catalog - must pre-exist in Gravitino)
+ └── schema (namespace - create via REST)
+ └── table01 (table - create via REST)
+```
+
+### Delimiter Convention
+
+The Lance REST API uses `$` as the default delimiter to separate namespace
levels in URIs. When making HTTP requests:
+
+- **URL Encoding Required**: `$` must be URL-encoded as `%24`
+- **Example**: `lance_catalog$schema$table01` becomes
`lance_catalog%24schema%24table01` in URLs
+
+**Common Delimiters:**
+```
+Namespace path: lance_catalog.schema.table01
+URI representation: lance_catalog$schema$table01
+URL encoded: lance_catalog%24schema%24table01
+```
+
+:::caution Important Limitations
+- Currently supports only **two levels of namespaces** before tables
+- Tables **cannot** be nested deeper than schema level
+- Parent catalog must be created in Gravitino before using Lance REST API
+- Metadata operations require Gravitino server to be available
+- Namespace deletion is recursive and irreversible
+:::
+- Currently supports only **two levels of namespaces** before tables
+- Tables **cannot** be nested deeper than schema level
+- Parent catalog must be created in Gravitino before using Lance REST API
+:::
Review Comment:
Duplicated content
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