Struct WalChangeCapture 

pub struct WalChangeCapture { /* private fields */ }

Postgres change capture over logical replication (pgoutput).

Exposes the two ChangeCapture capabilities the engine orchestrates:

• live connects to a replication slot and streams committed row changes as thin Changes. Resume is the slot’s: its confirmed_flush_lsn is the durable cursor on the server, advanced as the engine confirms changes (see Ack).
• snapshot reads current rows over an ordinary SQL connection for an initial backfill (see the crate-private backfill). The engine calls it only for tables backing an index the sink reports as unseeded.

Prerequisites

The server must have wal_level = logical and the configured publication must already exist and cover every table any index reads from. The replication slot is created automatically on first connect if it does not exist yet.

Implementations

impl WalChangeCapture

pub fn new(config: ReplicationConfig, connection_url: impl Into<String>) -> Self

Create a capture from a pgwire-replication configuration and the ordinary SQL connection URL the snapshot reads through (the same URL the document builder connects with).

Leave config.start_lsn at Lsn::ZERO to resume from the slot’s confirmed_flush_lsn — the usual choice.

Trait Implementations

impl ChangeCapture for WalChangeCapture

fn lag<'life0, 'async_trait>( &'life0 self, ) -> Pin<Box<dyn Future<Output = Result<Option<u64>>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Bytes between the slot’s confirmed_flush_lsn and the server’s current WAL LSN — how far behind the destination is. Returns None until the slot exists (it is created on the first live connect).

fn live<'life0, 'async_trait>( &'life0 self, ) -> Pin<Box<dyn Future<Output = Result<BoxStream<'static, Result<Change>>>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Connect, ensure setup, resume from the last confirmed point, and stream live changes.

fn snapshot<'life0, 'life1, 'async_trait>( &'life0 self, tables: &'life1 [SnapshotTable], ) -> Pin<Box<dyn Future<Output = Result<BoxStream<'static, Result<Change>>>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Snapshot the current rows of tables as a finite stream of Upsert changes — the rows to seed an index with. The stream ends when the snapshot is complete; there is no in-band boundary marker.

impl Clone for WalChangeCapture

fn clone(&self) -> WalChangeCapture

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for WalChangeCapture

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.