postgresql-api.md

Common API

In this documentation, we will focus on the common API. This module includes the core of BatchJS. This API allows you to create your own custom jobs and steps using the common interface.

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Table of Contents

• PostgresBatchEntityReader
• PostgresBatchEntityWriter

PostgresBatchEntityReader

extends AbstractBatchEntityReaderStream

Class that reads data in batches of a specified size using PostgreSQL cursors.

Constructor

Name	Description	Type
options	The options for the PostgresBatchEntityReader.	PostgresBatchEntityReaderOptions
options.pool	The PostgreSQL connection pool.	Pool
options.query	SQL query to be executed (without LIMIT and OFFSET).	string
options.rowToEntity	Function that converts a row to an entity.	function

fetch (function)

protected

Fetches a batch of data using a PostgreSQL cursor.

Parameters

Name	Description	Type
size	The size of the batch to fetch.	number

Returns

Type	Description
Promise.<BatchData.<T>>	A promise that resolves with the batch of data.

initializeCursor (function)

private

Initializes the cursor for the query if not already initialized.

Returns

Type	Description
Promise.<{cursorName:string, client:PoolClient}>	A promise that resolves when the cursor is initialized.

closeCursor (function)

private

Closes the cursor and releases the client connection.

Returns

Type	Description
Promise.<void>	A promise that resolves when the cursor is closed.

_destroy (function)

Destroys the reader by closing the cursor and releasing resources.

Parameters

Name	Description	Type
error	The error that caused the destruction.	Error, null
callback	The callback function to be executed after destruction.	function

PostgresBatchEntityWriter

extends AbstractBatchEntityWriterStream

Class that writes data in batches of a specified size in PostgreSQL databases.

Constructor

Name	Description	Type
options	The options for the PostgresBatchEntityWriter.	PostgresBatchEntityWriterOptions
options.pool	The PostgreSQL connection pool.	Pool
options.saveEntity	Function that saves an entity in the database.	function

batchWrite (function)

protected

Writes a batch of data to the storage.

Parameters

Name	Description	Type
chunk	The batch of data to write to the storage.	BatchData.<T>

Returns

Type	Description
Promise.<void>