Module ffi 

C FFI layer for LaminarDB.

Enable with the ffi feature flag:

laminar-db = { version = "0.1", features = ["ffi"] }

This module provides extern "C" functions for calling LaminarDB from C and any language with C FFI support (Python, Java, Node.js, .NET, etc.). C FFI layer for LaminarDB.

This module provides extern "C" functions for calling LaminarDB from C and any language with C FFI support (Python, Java, Node.js, .NET, etc.).

Design

• Opaque handles: C sees pointers, not struct layouts
• Explicit memory management: Caller frees with *_free() functions
• Error codes: All functions return i32 (0 = success, negative = error)
• Out-parameters: Results returned via pointer arguments
• Thread-local errors: laminar_last_error() returns the last error message

Example (C)

#include "laminar.h"

int main() {
    LaminarConnection* conn = NULL;
    int32_t rc = laminar_open(&conn);
    if (rc != LAMINAR_OK) {
        printf("Error: %s\n", laminar_last_error());
        return 1;
    }

    rc = laminar_execute(conn, "CREATE SOURCE test (id BIGINT)", NULL);
    laminar_close(conn);
    return 0;
}

Structs

LaminarConnection

Opaque connection handle for FFI.

LaminarQueryResult

Opaque query result handle for FFI.

LaminarQueryStream

Opaque query stream handle for FFI.

LaminarRecordBatch

Opaque record batch handle for FFI.

LaminarSchema

Opaque schema handle for FFI.

LaminarSubscriptionHandle

Opaque handle for a callback-based subscription.

LaminarWriter

Opaque writer handle for FFI.

Constants

LAMINAR_ERR_CONNECTION

Connection error.

LAMINAR_ERR_INGESTION

Data ingestion error.

LAMINAR_ERR_INTERNAL

Internal error.

LAMINAR_ERR_INVALID_UTF8

Invalid UTF-8 string.

LAMINAR_ERR_NULL_POINTER

Null pointer was passed to a function.

LAMINAR_ERR_QUERY

Query execution error.

LAMINAR_ERR_SCHEMA_MISMATCH

Schema mismatch error.

LAMINAR_ERR_SHUTDOWN

Database is shutting down.

LAMINAR_ERR_SUBSCRIPTION

Subscription error.

LAMINAR_ERR_TABLE_EXISTS

Table/source already exists.

LAMINAR_ERR_TABLE_NOT_FOUND

Table/source not found.

LAMINAR_EVENT_DELETE

Event type: delete (-1 weight).

LAMINAR_EVENT_INSERT

Event type: insert (+1 weight).

LAMINAR_EVENT_SNAPSHOT

Event type: snapshot (initial state load).

LAMINAR_EVENT_UPDATE

Event type: update (decomposed to delete + insert).

LAMINAR_EVENT_WATERMARK

Event type: watermark progress (no data).

LAMINAR_OK

Success return code.

Functions

laminar_batch_create^⚠

Create a RecordBatch from Arrow C Data Interface for writing.

laminar_batch_export^⚠

Export a RecordBatch to the Arrow C Data Interface.

laminar_batch_export_column^⚠

Export a single column from a RecordBatch to the Arrow C Data Interface.

laminar_batch_free^⚠

Free a record batch handle.

laminar_batch_import^⚠

Import a RecordBatch from the Arrow C Data Interface.

laminar_batch_num_columns^⚠

Get the number of columns in a record batch.

laminar_batch_num_rows^⚠

Get the number of rows in a record batch.

laminar_clear_error

Clear the last error.

laminar_close^⚠

Close a database connection.

laminar_execute^⚠

Execute a SQL statement.

laminar_get_schema^⚠

Get schema for a source.

laminar_is_closed^⚠

Check if the connection is closed.

laminar_last_error

Get the last error message.

laminar_last_error_code

Get the last error code.

laminar_list_sources^⚠

List all sources as JSON array.

laminar_open^⚠

Open a new database connection.

laminar_query^⚠

Execute a query and get materialized results.

laminar_query_stream^⚠

Execute a query with streaming results.

laminar_result_free^⚠

Free a query result handle.

laminar_result_get_batch^⚠

Get a batch by index from a query result.

laminar_result_num_batches^⚠

Get the number of batches in a query result.

laminar_result_num_rows^⚠

Get the total row count from a query result.

laminar_result_schema^⚠

Get the schema from a query result.

laminar_schema_export^⚠

Export just the schema to the Arrow C Data Interface.

laminar_schema_field_name^⚠

Get the name of a field by index.

laminar_schema_field_type^⚠

Get the type of a field by index.

laminar_schema_free^⚠

Free a schema handle.

laminar_schema_num_fields^⚠

Get the number of fields in a schema.

laminar_start^⚠

Start the streaming pipeline.

laminar_stream_cancel^⚠

Cancel a query stream.

laminar_stream_free^⚠

Free a query stream handle.

laminar_stream_is_active^⚠

Check if a query stream is still active.

laminar_stream_next^⚠

Get the next batch from a query stream (blocking).

laminar_stream_schema^⚠

Get the schema from a query stream.

laminar_stream_try_next^⚠

Try to get the next batch from a query stream (non-blocking).

laminar_string_free^⚠

Free a string allocated by LaminarDB.

laminar_subscribe_callback^⚠

Create a callback-based subscription.

laminar_subscription_cancel^⚠

Cancel a callback-based subscription.

laminar_subscription_free^⚠

Free a subscription handle.

laminar_subscription_is_active^⚠

Check if a subscription is still active.

laminar_subscription_user_data^⚠

Get the user data pointer from a subscription handle.

laminar_version

Get the LaminarDB library version.

laminar_writer_close^⚠

Close the writer and release resources.

laminar_writer_create^⚠

Create a writer for a source.

laminar_writer_flush^⚠

Flush buffered data.

laminar_writer_free^⚠

Free a writer handle.

laminar_writer_write^⚠

Write a record batch to the source.

Type Aliases

LaminarErrorCallback

Callback function type for errors.

LaminarSubscriptionCallback

Callback function type for subscription data.