Struct ChangeWriter 

pub struct ChangeWriter<'a> { /* private fields */ }

Writes changes to the target PostgreSQL database using upsert operations.

The ChangeWriter handles batched upserts within transactions for efficiency and atomicity. It dynamically builds INSERT … ON CONFLICT DO UPDATE queries based on table schema.

Implementations

impl<'a> ChangeWriter<'a>

pub fn new(client: &'a Client) -> Self

Create a new ChangeWriter for the given PostgreSQL client connection.

pub fn client(&self) -> &Client

Get a reference to the underlying client.

Useful for callers that need to perform additional queries.

pub async fn apply_batch( &self, schema: &str, table: &str, primary_key_columns: &[String], all_columns: &[String], rows: Vec<Vec<Box<dyn ToSql + Sync + Send>>>, ) -> Result<u64>

Apply a batch of rows to a table using upsert (INSERT … ON CONFLICT DO UPDATE).

Uses batching internally to stay within PostgreSQL’s parameter limits. Each batch is executed as a separate query (PostgreSQL auto-commits). Automatically retries with smaller batches if “value too large” errors occur.

Arguments

• schema - The schema name (e.g., “public”)
• table - The table name
• primary_key_columns - Column names that form the primary key
• all_columns - All column names in the order they appear in rows
• rows - The rows to upsert, each row is a vector of values

Returns

The number of rows affected.

pub async fn apply_row( &self, schema: &str, table: &str, primary_key_columns: &[String], all_columns: &[String], values: Vec<Box<dyn ToSql + Sync + Send>>, ) -> Result<u64>

Apply a single row using upsert.

For single rows, this is more efficient than creating a batch.

pub async fn delete_rows( &self, schema: &str, table: &str, primary_key_columns: &[String], pk_values: Vec<Vec<Box<dyn ToSql + Sync + Send>>>, ) -> Result<u64>

Delete rows by primary key values.

Used by the reconciler to remove rows that no longer exist in source. Executes deletes in batches to stay within PostgreSQL parameter limits.