Get Historical Bitcoin Prices on GDAX in CSV Format
This is my first ever response on any forum so I hope you find this helpful. 

I think your question is "is it possible to get one year worth minute by minute data from gdax?". I only recently started trading with gdax via it's API but i have been trading with kraken's API for a while now and my experience with all crypto currencies so far is that you can only get a few days worth of historical data or ticks. However, if you want minute by minute data from the API, then you will have to query the data at some interval (maybe every minute). Note that the frequency of such queries are usually limited by a rate limit often determined by the exchange.

Also, I do not think Coinbase is an exchange in the sense conventional sense. I see coinbase and gdax as different business units of the same enity. Hence, I suspect that whatever trade or tick information you get from either of the two will be the same. However, they function differently and have two different category of people they cater to. Coinbase API is primarily for building phone applications with only basic features e.g. buy, sell, send, historical data.

However, gdax caters to the more sophisticated trader with more advanced features like limit order, margin trading, OHLC data etc.

You should check the links below to see if there are features that may attend to your needs

https://developers.coinbase.com/
https://docs.gdax.com/?javascript#introduction