@ovotech/bigquery-pg-sink
v2.0.1
Published
Stream BigQuery query results into a postgres database
Downloads
68
Maintainers
Keywords
Readme
BigQuery PG Sink
Stream the results of query made by nodejs-bigquery into a postgres database.
Using
yarn add @ovotech/bigquery-pg-sink
Creating a Sink
const pg = new Client('postgresql://postgres:[email protected]:5432/postgres');
const pgSink = new BigQueryPGSinkStream({
pg: db,
insert: insertQuery,
});
bigquery
.createQueryStream('___BIGQUERY_QUERY_STRING___')
.pipe(pgSink)
Creating insert functions
You can directly map each record returned to it a single insert query
import { RowMetadata } from '@google-cloud/bigquery';
import { BigQueryPGSinkStream, InsertBatch } from '@ovotech/bigquery-pg-sink';
import { Client } from 'pg';
export const insertQuery = (rows: RowMetadata): InsertBatch[] => {
return rows.map(bigQueryResult => ({
query: `INSERT INTO table
(
id,
balance
) VALUES $1, $2
`,
values: [bigQueryResult.id, bigQueryResult.balance],
}));
It is possible to speed up the insertion by using a bulk insert, however this would mean you need to programatically build up the query based on the size of the rows passed to your insertQuery function
import { RowMetadata } from '@google-cloud/bigquery';
import { BigQueryPGSinkStream, InsertBatch } from '@ovotech/bigquery-pg-sink';
import { Client } from 'pg';
export const insertQuery = (rows: RowMetadata): InsertBatch[] => {
// transform each result into a flat array of values
// i.e. [1, 200, 2, 300]
const flatRows = rows.map(bigQueryResult => {
return [
bigQueryResult.id,
bigQueryResult.balance,
]
}).flat();
// generate the values insert string
// i.e. ($1,$2,$3,.....)
const columns = [...Array(11)];
const insertValuesString = rows
.map(
(_, rowIndex) =>
`(${columns
.map((row: any, index) => '$' + {index + 1 + rowIndex * columns.length})
.join(',')})`,
)
.join(',');
return [{
query: `INSERT INTO table
(
id,
balance
) VALUES ${insertValuesString}
`,
values: flatRows,
}];
};
Coding style (linting, etc) tests
Style is maintained with prettier and tslint
yarn lint
Deployment
Deployment is preferment by lerna automatically on merge / push to master, but you'll need to bump the package version numbers yourself. Only updated packages with newer versions will be pushed to the npm registry.
Contributing
Have a bug? File an issue with a simple example that reproduces this so we can take a look & confirm.
Want to make a change? Submit a PR, explain why it's useful, and make sure you've updated the docs (this file) and the tests (see test folder).
License
This project is licensed under Apache 2 - see the LICENSE file for details