Use parameterized queries with InfluxQL

Parameterized queries in InfluxDB Cloud Dedicated let you dynamically and safely change values in a query. If your application code allows user input to customize values or expressions in a query, use a parameterized query to make sure untrusted input is processed strictly as data and not executed as code.

Parameterized queries:

• help prevent injection attacks, which can occur if input is executed as code
• help make queries more reusable

In InfluxDB v3, a parameterized query is an InfluxQL or SQL query that contains one or more named parameter placeholders–variables that represent input data.

• Use parameters in WHERE expressions
• Parameter data types
  • Data type examples
  • Time expressions
  • Not compatible with parameters
• Parameterize an SQL query
• Execute parameterized InfluxQL queries
  • Use InfluxDB Flight RPC clients
• Client support for parameterized queries
• Not supported

Use parameters in WHERE expressions

You can use parameters in WHERE clause predicate expressions-–for example, the following query contains a $temp parameter:

SELECT * FROM measurement WHERE temp > $temp

When executing a query, you specify parameter name-value pairs. The value that you assign to a parameter must be one of the parameter data types.

{"temp": 22.0}

The InfluxDB Querier parses the query text with the parameter placeholders, and then generates query plans that replace the placeholders with the values that you provide. This separation of query structure from input data ensures that input is treated as one of the allowed data types and not as executable code.

Parameter data types

A parameter value can be one of the following data types:

• Null
• Boolean
• Unsigned integer (u_int64)
• Integer (int64)
• Double (float64)
• String

Data type examples

{
  "string": "Living Room",
  "double": 3.14,
  "unsigned_integer": 1234,
  "integer": -1234,
  "boolean": false,
  "null": Null,
}

Time expressions

To parameterize time bounds, substitute a parameter for a timestamp literal–for example:

SELECT *
FROM home
WHERE time >= $min_time

For the parameter value, specify the timestamp literal as a string–for example:

// Assign a timestamp string literal to the min_time parameter.
parameters := influxdb3.QueryParameters{
    "min_time": "2022-01-01 00:00:00.00",
}

InfluxDB executes the query as the following:

SELECT *
FROM home
WHERE time >= '2022-01-01 00:00:00.00'

Not compatible with parameters

If you use parameters for the following, your query might not work as you expect:

• In clauses other than WHERE, such as SELECT or GROUP BY
• As function arguments, such as avg($temp)
• In place of identifiers, such as column or table names
• In place of duration literals, such as time > now() - $min_duration

Parameterize an SQL query

To use a parameterized query, do the following:

1. In your query text, use the $parameter syntax to reference a parameter name–for example, the following query contains $room and $min_temp parameter placeholders:

   SELECT *
   FROM home
   WHERE time > now() - 7d
   AND temp >= $min_temp
   AND room = $room
   

2. Provide a value for each parameter name. If you don’t assign a value for a parameter, InfluxDB returns an error. The syntax for providing parameter values depends on the client you use–for example:

   Go

   // Define a QueryParameters struct--a map of parameters to input values.
   parameters := influxdb3.QueryParameters{
       "room": "Kitchen",
       "min_temp": 20.0,
   }
   

After InfluxDB receives your request and parses the query, it executes the query as

SELECT *
FROM home
WHERE time > now() - 7d
AND temp >= 20.0
AND room = 'Kitchen'

Execute parameterized InfluxQL queries

Use InfluxDB Flight RPC clients

Using the InfluxDB v3 native Flight RPC protocol and supported clients, you can send a parameterized query and a list of parameter name-value pairs. InfluxDB Flight clients that support parameterized queries pass the parameter name-value pairs in a Flight ticket params field.

The following examples show how to use client libraries to execute parameterized InfluxQL queries:

import (
    "context"
    "fmt"
    "io"
    "os"
    "text/tabwriter"
    "time"
    "github.com/apache/arrow/go/v14/arrow"
    "github.com/InfluxCommunity/influxdb3-go/influxdb3"
)

func Query(query string, parameters influxdb3.QueryParameters,
 options influxdb3.QueryOptions) error {
    url := os.Getenv("INFLUX_HOST")
    token := os.Getenv("INFLUX_TOKEN")
    database := os.Getenv("INFLUX_DATABASE")

    // Instantiate the influxdb3 client.
    client, err := influxdb3.New(influxdb3.ClientConfig{
        Host:     url,
        Token:    token,
        Database: database,
    })

    if err != nil {
        panic(err)
    }

    // Ensure the client is closed after the Query function finishes.
    defer func(client *influxdb3.Client) {
        err := client.Close()
        if err != nil {
            panic(err)
        }
    }(client)

    // Call the client's QueryWithParameters function.
    // Provide the query, parameters, and the InfluxQL QueryType option.
    iterator, err := client.QueryWithParameters(context.Background(), query,
    parameters, influxdb3.WithQueryType(options.QueryType))

    // Create a buffer for storing rows as you process them.
    w := tabwriter.NewWriter(io.Discard, 4, 4, 1, ' ', 0)
    w.Init(os.Stdout, 0, 8, 0, '\t', 0)

    fmt.Fprintf(w, "time\troom\tco\thum\ttemp\n")

    // Format and write each row to the buffer.
    // Process each row as key-value pairs.
    for iterator.Next() {
        row := iterator.Value()
        // Use Go arrow and time packages to format unix timestamp
        // as a time with timezone layout (RFC3339 format)
        time := (row["time"].(arrow.Timestamp)).
                ToTime(arrow.Nanosecond).Format(time.RFC3339)

        fmt.Fprintf(w, "%s\t%s\t%d\t%.1f\t%.1f\n",
            time, row["room"], row["co"], row["hum"], row["temp"])
    }
    w.Flush()

    return nil
}

func main() {
    // Use the $placeholder syntax in a query to reference parameter placeholders
    // for input data.
    // The following InfluxQL query contains the placeholders $room and $min_temp.
    query := `
        SELECT *
        FROM home
        WHERE time > now() - 7d
        AND temp >= $min_temp
        AND room = $room`

    // Define a QueryParameters struct--a map of placeholder names to input values.
    parameters := influxdb3.QueryParameters{
        "room": "Kitchen",
        "min_temp": 20.0,
    }

    Query(query, parameters, influxdb3.QueryOptions{
        QueryType: influxdb3.InfluxQL,
    })
}

Client support for parameterized queries

• Not all InfluxDB v3 Flight clients support parameterized queries.
• InfluxDB doesn’t currently support parameterized queries or DataFusion prepared statements for Flight SQL or Flight SQL clients.
• InfluxDB v3 SQL and InfluxQL parameterized queries aren’t supported in InfluxDB v1 and v2 clients.

Not supported

Currently, parameterized queries in InfluxDB Cloud Dedicated don’t provide the following:

• support for DataFusion prepared statements
• query caching, optimization, or performance benefits