Use a PostgreSQL result cursor from node with an easy to use API.
Sometimes you need to iterate through a table in chunks. It's extremely inefficient to use hand-crafted
OFFSET queries to do this.
PostgreSQL provides built-in functionality to fetch a "cursor" to your results and page through the cursor efficiently fetching chunks of the results with full MVCC compliance.
This actually ends up pairing very nicely with node's asyncness and handling a lot of data. PostgreSQL is rad.
var Cursor =var pg =pg;
var Cursor = require('pg-cursor')
constructor Cursor(string queryText, array queryParameters)
Creates an instance of a query cursor. Pass this instance to node-postgres
cursor#read(int rowCount, function callback(Error err, Array rows, Result result)
rowCount rows from the cursor instance. The
If the cursor has read to the end of the result sets all subsequent calls to
cursor#read will return a 0 length array of rows. I'm open to other ways to signal the end of a cursor, but this has worked out well for me so far.
result is a special https://github.com/brianc/node-postgres/wiki/Query#result-object object that can be used to accumulate rows.
cursor#close(function callback(Error err))
Closes the backend portal before itterating through the entire result set. Useful when you want to 'abort' out of a read early but continue to use the same client for other queries after the cursor is finished.
$ npm install pg-cursor
note: this depends on either
npm install pg or
The MIT License (MIT)
Copyright (c) 2013 Brian M. Carlson
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