mirror of
https://github.com/FlipsideCrypto/snowflake-promise.git
synced 2026-02-06 11:18:25 +00:00
49 lines
1.6 KiB
JavaScript
49 lines
1.6 KiB
JavaScript
//
|
||
// Use this when processing large datasets (or when retrieving only a few rows
|
||
// from a large result set). This is common when doing batch processing.
|
||
//
|
||
// This avoids loading the entire result set into memory, and lets you work on
|
||
// one row at a time.
|
||
//
|
||
|
||
const Snowflake = require('snowflake-promise').Snowflake;
|
||
|
||
async function main() {
|
||
const snowflake = new Snowflake({
|
||
account: '<account name>',
|
||
username: '<username>',
|
||
password: '<password>',
|
||
database: 'SNOWFLAKE_SAMPLE_DATA',
|
||
schema: 'TPCH_SF1',
|
||
warehouse: 'DEMO_WH'
|
||
});
|
||
|
||
await snowflake.connect();
|
||
|
||
// this query returns tens of thousands of rows
|
||
const statement = snowflake.createStatement({
|
||
sqlText: 'SELECT * FROM CUSTOMER WHERE C_MKTSEGMENT=:1',
|
||
binds: ['AUTOMOBILE'],
|
||
// This tells Snowflake not to bother building an array of all the result
|
||
// rows. That’s a good thing when streaming a huge result set:
|
||
streamResult: true
|
||
});
|
||
|
||
// You don’t have to await this, you can begin streaming immediately.
|
||
await statement.execute();
|
||
|
||
// How many rows in the result set? This only works if you await-ed
|
||
// execute(), above. Otherwise, the number of rows is not known yet.
|
||
console.log(`the query result set has ${statement.getNumRows()} rows`);
|
||
|
||
// Let’s process rows 250-275, one by one. (If you omit the argument for
|
||
// streamRows(), all rows will be processed.)
|
||
statement.streamRows({ start: 250, end: 275 })
|
||
.on('error', console.error)
|
||
.on('data', row => console.log(`customer name is: ${row['C_NAME']}`))
|
||
.on('end', () => console.log('done processing'))
|
||
;
|
||
}
|
||
|
||
main();
|