omnia-azure-table

Azure Table Storage backend for the Omnia WASI runtime, implementing the wasi-jsondb interface.

Azure Table Storage is a NoSQL key-value store. This crate maps the jsondb document model onto Azure Table entities: top-level JSON fields are flattened into entity properties so that server-side OData $filter queries work, while nested objects are serialized as JSON string properties.

MSRV: Rust 1.93

Key Mapping

The collection string encodes {table}/{partitionKey} (split on the first /). The document id maps to the Azure Table RowKey.

jsondb concept	Azure Table equivalent
`collection`	`{table}/{PartitionKey}`
`id`	`RowKey`
`document.data`	Flattened entity properties

Example: get("users/tenant-a", "user-123") → table=users, PK=tenant-a, RK=user-123.

A table-only collection ("users" without a /) is allowed for query() (cross-partition scan) but rejected for point operations (get, insert, put, delete).

`OData` Type Mapping

Top-level JSON fields are flattened into typed entity properties. The crate automatically adds @odata.type annotations where Azure Table cannot infer the type from the JSON representation alone.

JSON value	Azure `OData` type	Annotation added?
`true` / `false`	`Edm.Boolean`	No (inferred)
integer ≤ `i32` range	`Edm.Int32`	No (inferred)
integer > `i32` range	`Edm.Int64`	Yes
floating point	`Edm.Double`	Yes
string	`Edm.String`	No (inferred)
`null`	(skipped)	N/A
array / object	`Edm.String` (JSON-serialized)	No

Edm.DateTime, Edm.Guid, and Edm.Binary require the document to include explicit @odata.type annotations — the crate does not attempt to guess these from string values.

Supported Operations

Operation	Description
`get`	Point read by `PartitionKey` + `RowKey`
`insert`	Insert new entity (fails if exists)
`put`	Upsert entity
`delete`	Delete entity (returns whether it existed)
`query`	Filtered listing with `OData` `$filter` and pagination
`ensure_table`	Creates a table if it does not exist (admin helper)

Filter Support

Filter	Supported	Notes
`Compare` (eq/ne/gt/gte/lt/lte)	Yes	Translated to `OData` operators
`InList` / `NotInList`	Yes	Expanded to OR chains
`And` / `Or` / `Not`	Yes	Supported when all children are supported
`Contains` / `StartsWith` / `EndsWith`	No	Rejected with error
`IsNull` / `IsNotNull`	No	Rejected with error
`offset`	No	Rejected with error — use continuation tokens
`continuation`	Yes	Native Azure Table continuation tokens

Unsupported filters and query options return an error rather than silently falling back to client-side evaluation, which could pull unbounded data from the table service. Azure Table's OData $filter does not support string functions or null checks, and there is no $skip — see Querying tables and entities.

Note: order_by is ignored. Azure Table returns results in PartitionKey / RowKey order; there is no server-side $orderby. Callers that need a different sort order should sort after retrieval.

Why not `azure_data_tables`?

The azure_data_tables crate is on a legacy branch with no official replacement planned. This crate calls the REST API directly and leaves business object mapping to the WebAssembly guest.

Configuration

Variable	Required	Default	Description
`AZURE_STORAGE_ACCOUNT`	yes		Storage account name
`AZURE_STORAGE_KEY`	yes		Storage account access key
`AZURE_TABLE_ENDPOINT`	no	`https://{account}.table.core.windows.net`	Table service endpoint URL

Set AZURE_TABLE_ENDPOINT to override the default public-cloud URL. Common values:

Azurite: http://127.0.0.1:10002/{account}
Azure sovereign cloud: the appropriate table.core.* URL for your region

Usage

use omnia::Backend;
use omnia_azure_table::Client;

let options = omnia_azure_table::ConnectOptions::from_env()?;
let client = Client::connect_with(options).await?;

// Create the table if needed (admin helper, not part of wasi-jsondb)
client.ensure_table("my_table").await?;

License

MIT OR Apache-2.0

omnia-azure-table 0.24.0