# Postgres

Kubemq postgres target connector allows services using kubemq server to access postgres database services.

## Prerequisites

The following are required to run the postgres target connector:

* kubemq cluster
* postgres server
* kubemq-targets deployment

## Configuration

Postgres target connector configuration properties:

| Properties Key                     | Required | Description                                 | Example                                                                  |
| ---------------------------------- | -------- | ------------------------------------------- | ------------------------------------------------------------------------ |
| connection                         | yes      | postgres connection string address          | "postgres\://postgres:postgres\@localhost:5432/postgres?sslmode=disable" |
| max\_idle\_connections             | no       | set max idle connections                    | "10"                                                                     |
| max\_open\_connections             | no       | set max open connections                    | "100"                                                                    |
| connection\_max\_lifetime\_seconds | no       | set max lifetime for connections in seconds | "3600"                                                                   |

Example:

```yaml
bindings:
  - name: kubemq-query-postgres
    source:
      kind: kubemq.query
      name: kubemq-query
      properties:
        address: "kubemq-cluster:50000"
        client_id: "kubemq-query-postgres-connector"
        auth_token: ""
        channel: "query.postgres"
        group:   ""
        auto_reconnect: "true"
        reconnect_interval_seconds: "1"
        max_reconnects: "0"
    target:
      kind: stores.postgres
      name: target-postgres
      properties:
        connection: "postgres://postgres:postgres@localhost:5432/postgres?sslmode=disable"
        max_idle_connections: "10"
        max_open_connections: "100"
        connection_max_lifetime_seconds: "3600"
```

## Usage

### Query Request

Query request metadata setting:

| Metadata Key | Required | Description         | Possible values |
| ------------ | -------- | ------------------- | --------------- |
| method       | yes      | set type of request | "query"         |

Query request data setting:

| Data Key | Required | Description  | Possible values    |
| -------- | -------- | ------------ | ------------------ |
| data     | yes      | query string | base64 bytes array |

Example:

Query string: `SELECT id,title,content FROM post;`

```javascript
{
  "metadata": {
    "method": "query"
  },
  "data": "U0VMRUNUIGlkLHRpdGxlLGNvbnRlbnQgRlJPTSBwb3N0Ow=="
}
```

### Exec Request

Exec request metadata setting:

| Metadata Key     | Required | Description                            | Possible values     |
| ---------------- | -------- | -------------------------------------- | ------------------- |
| method           | yes      | set type of request                    | "exec"              |
| isolation\_level | no       | set isolation level for exec operation | ""                  |
|                  |          |                                        | "read\_uncommitted" |
|                  |          |                                        | "read\_committed"   |
|                  |          |                                        | "repeatable\_read"  |
|                  |          |                                        | "serializable"      |
|                  |          |                                        |                     |

Exec request data setting:

| Data Key | Required | Description | Possible values    |
| -------- | -------- | ----------- | ------------------ |
| data     | yes      | exec string | base64 bytes array |

Example:

Exec string:

```sql
INSERT INTO post(ID,TITLE,CONTENT) VALUES (1,NULL,'Content One'),(2,'Title Two','Content Two');
```

```javascript
{
  "metadata": {
    "method": "exec",
    "isolation_level": "read_uncommitted"
  },
  "data": "SU5TRVJUIElOVE8gcG9zdChJRCxUSVRMRSxDT05URU5UKSBWQUxVRVMKCSAgICAgICAgICAgICAgICAgICAgICAgKDEsTlVMTCwnQ29udGVudCBPbmUnKSwKCSAgICAgICAgICAgICAgICAgICAgICAgKDIsJ1RpdGxlIFR3bycsJ0NvbnRlbnQgVHdvJyk7" 
}
```

### Transaction Request

Transaction request metadata setting:

| Metadata Key     | Required | Description                            | Possible values     |
| ---------------- | -------- | -------------------------------------- | ------------------- |
| method           | yes      | set type of request                    | "transaction"       |
| isolation\_level | no       | set isolation level for exec operation | ""                  |
|                  |          |                                        | "read\_uncommitted" |
|                  |          |                                        | "read\_committed"   |
|                  |          |                                        | "repeatable\_read"  |
|                  |          |                                        | "serializable"      |

Transaction request data setting:

| Data Key | Required | Description   | Possible values    |
| -------- | -------- | ------------- | ------------------ |
| data     | yes      | string string | base64 bytes array |

Example:

Transaction string:

```sql
DROP TABLE IF EXISTS post;
CREATE TABLE post (
         ID serial,
         TITLE varchar(40),
         CONTENT varchar(255),
         CONSTRAINT pk_post PRIMARY KEY(ID)
       );
INSERT INTO post(ID,TITLE,CONTENT) VALUES
                       (1,NULL,'Content One'),
                       (2,'Title Two','Content Two');
```

```javascript
{
  "metadata": {
    "key": "your-postgres-key",
    "method": "delete"
  },
  "data": "CURST1AgVEFCTEUgSUYgRVhJU1RTIHBvc3Q7CiAgICBDUkVBVEUgVEFCTEUgcG9zdCAoCgkgICAgICAgICBJRCBzZXJpYWwsCgkgICAgICAgICBUSVRMRSB2YXJjaGFyKDQwKSwKCSAgICAgICAgIENPTlRFTlQgdmFyY2hhcigyNTUpLAoJICAgICAgICAgQ09OU1RSQUlOVCBwa19wb3N0IFBSSU1BUlkgS0VZKElEKQoJICAgICAgICk7CiAgICBJTlNFUlQgSU5UTyBwb3N0KElELFRJVExFLENPTlRFTlQpIFZBTFVFUwoJICAgICAgICAgICAgICAgICAgICAgICAoMSxOVUxMLCdDb250ZW50IE9uZScpLAoJICAgICAgICAgICAgICAgICAgICAgICAoMiwnVGl0bGUgVHdvJywnQ29udGVudCBUd28nKTs="
}
```