pg-cursor

import { Client } from 'pg'; import Cursor from 'pg-cursor'; async function processLargeResult() { const client = new Client({ user: process.env.PGUSER ?? 'postgres', host: process.env.PGHOST ?? 'localhost', database: process.env.PGDATABASE ?? 'your_database', password: process.env.PGPASSWORD ?? 'password', port: parseInt(process.env.PGPORT ?? '5432', 10), }); await client.connect(); console.log('Connected to database.'); const query = 'SELECT id, data FROM large_table ORDER BY id'; // Replace large_table with your table const cursor = client.query(new Cursor(query)); const BATCH_SIZE = 100; let rowsProcessed = 0; try { while (true) { const rows = await new Promise<any[]>((resolve, reject) => { cursor.read(BATCH_SIZE, (err, batchRows) => { if (err) return reject(err); resolve(batchRows); }); }); if (rows.length === 0) { break; // No more rows to read } for (const row of rows) { // console.log(`Processing row ID: ${row.id}`); // Perform your row-specific logic here rowsProcessed++; } if (rows.length < BATCH_SIZE) { break; // Less than batch size means we've reached the end } } console.log(`Successfully processed ${rowsProcessed} rows using a cursor.`); } catch (error) { console.error('Error during cursor processing:', error); } finally { try { await cursor.close(); console.log('Cursor closed.'); } catch (closeError) { console.warn('Error closing cursor (might be already closed or connection issue):', closeError); } await client.end(); console.log('Database connection ended.'); } } processLargeResult().catch(err => console.error('Unhandled error:', err));