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Destroyed Queryqueue (markdown)

Brian C 2017-06-02 17:27:39 -05:00
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Queryqueue.md

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An advanced usage feature which might come in handy is using the internal query queue to queue up several queries in a row. __[[Clients|Client]]__ are responsible for creating __[[Queries|Query]]__ via the factory method Client#query. The __Client__ can create a new query before the client is connected to the server or while other queries are executing. Internally the __Client__ maintains a queue of __Query__ objects which are popped and executed as the preceding __Query__ completes. The error handling semantics here get really complicated and isn't recommended unless you're banging out a quick script and don't care about error handling or you really, really have some specific use case. This "feature" is mostly a hold-over from a bad design decision I made years ago, but have left to maintain backwards compatibility.
#### example
```javascript
var client = new Client(...);
var query1 = client.query("SELECT * FROM NOW()"); //query is queued. client is not connected
query1.on('end', function() {
console.log('query 1 completed');
});
var query2 = client.query("SELECT * FROM NOW()"); //also queued
query2.on('end', function() {
console.log('query 2 completed');
});
client.on('drain', function() {
console.log("drained");
});
//at this point nothing has been printed to the console
client.connect();
//this will print the following:
//query 1 completed
//query 2 completed
//drained
```
***
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