build-a-go-app-with-cockroachdb.md

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Build a Go App with CockroachDB	Learn how to use CockroachDB from a simple Go application with the Go pq driver.	true	false

Use pq Use GORM

This tutorial shows you how build a simple Go application with CockroachDB using a PostgreSQL-compatible driver or ORM.

We have tested the Go pq driver and the GORM ORM enough to claim beta-level support, so those are featured here. If you encounter problems, please open an issue with details to help us make progress toward full support.

Before you begin

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Step 1. Install the Go pq driver

To install the Go pq driver, run the following command:

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$ go get -u github.com/lib/pq

Step 2. Create the maxroach user and bank database

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Step 3. Generate a certificate for the maxroach user

Create a certificate and key for the maxroach user by running the following command. The code samples will run as this user.

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$ cockroach cert create-client maxroach --certs-dir=certs --ca-key=my-safe-directory/ca.key

Step 4. Run the Go code

Now that you have a database and a user, you'll run code to create a table and insert some rows, and then you'll run code to read and update values as an atomic transaction.

Basic statements

First, use the following code to connect as the maxroach user and execute some basic SQL statements, creating a table, inserting rows, and reading and printing the rows.

Download the basic-sample.go file, or create the file yourself and copy the code into it.

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{% include {{ page.version.version }}/app/basic-sample.go %}

Then run the code:

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$ go run basic-sample.go

The output should be:

Initial balances:
1 1000
2 250

Transaction (with retry logic)

Next, use the following code to again connect as the maxroach user but this time will execute a batch of statements as an atomic transaction to transfer funds from one account to another, where all included statements are either committed or aborted.

Download the txn-sample.go file, or create the file yourself and copy the code into it.

{% include copy-clipboard.html %}

{% include {{ page.version.version }}/app/txn-sample.go %}

With the default SERIALIZABLE isolation level, CockroachDB may require the client to retry a transaction in case of read/write contention. CockroachDB provides a generic retry function that runs inside a transaction and retries it as needed. For Go, the CockroachDB retry function is in the crdb package of the CockroachDB Go client.

To install the CockroachDB Go client, run the following command:

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$ go get -d github.com/cockroachdb/cockroach-go

Then run the code:

{% include copy-clipboard.html %}

$ go run txn-sample.go

The output should be:

Success

To verify that funds were transferred from one account to another, use the built-in SQL client:

{% include copy-clipboard.html %}

$ cockroach sql --certs-dir=certs -e 'SELECT id, balance FROM accounts' --database=bank

+----+---------+
| id | balance |
+----+---------+
|  1 |     900 |
|  2 |     350 |
+----+---------+
(2 rows)

Step 2. Create the maxroach user and bank database

{% include {{page.version.version}}/app/insecure/create-maxroach-user-and-bank-database.md %}

Step 3. Run the Go code

Now that you have a database and a user, you'll run code to create a table and insert some rows, and then you'll run code to read and update values as an atomic transaction.

Basic statements

First, use the following code to connect as the maxroach user and execute some basic SQL statements, creating a table, inserting rows, and reading and printing the rows.

Download the basic-sample.go file, or create the file yourself and copy the code into it.

{% include copy-clipboard.html %}

{% include {{ page.version.version }}/app/insecure/basic-sample.go %}

Then run the code:

{% include copy-clipboard.html %}

$ go run basic-sample.go

The output should be:

Initial balances:
1 1000
2 250

Transaction (with retry logic)

Next, use the following code to again connect as the maxroach user but this time will execute a batch of statements as an atomic transaction to transfer funds from one account to another, where all included statements are either committed or aborted.

Download the txn-sample.go file, or create the file yourself and copy the code into it.

{% include copy-clipboard.html %}

{% include {{ page.version.version }}/app/insecure/txn-sample.go %}

With the default SERIALIZABLE isolation level, CockroachDB may require the client to retry a transaction in case of read/write contention. CockroachDB provides a generic retry function that runs inside a transaction and retries it as needed. For Go, the CockroachDB retry function is in the crdb package of the CockroachDB Go client. Clone the library into your $GOPATH as follows:

{% include copy-clipboard.html %}

$ mkdir -p $GOPATH/src/github.com/cockroachdb

{% include copy-clipboard.html %}

$ cd $GOPATH/src/github.com/cockroachdb

{% include copy-clipboard.html %}

$ git clone [email protected]:cockroachdb/cockroach-go.git

Then run the code:

{% include copy-clipboard.html %}

$ go run txn-sample.go

The output should be:

Success

To verify that funds were transferred from one account to another, use the built-in SQL client:

{% include copy-clipboard.html %}

$ cockroach sql --insecure -e 'SELECT id, balance FROM accounts' --database=bank

+----+---------+
| id | balance |
+----+---------+
|  1 |     900 |
|  2 |     350 |
+----+---------+
(2 rows)

What's next?

Read more about using the Go pq driver.

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