---
title: Design your schema
description: Use schema design guidelines to improve write and query performance in your InfluxDB cluster.
url: https://docs.influxdata.com/influxdb3/clustered/install/optimize-cluster/design-schema/
estimated_tokens: 1127
product: InfluxDB Clustered
version: clustered
---

# Design your schema

-   Install InfluxDB Clustered
-   Phase 3: Optimize your cluster

Schema design can have a significant impact on both write and query performance in your InfluxDB cluster. The items below cover high-level considerations and recommendation. For detailed recommendations, see [Schema design recommendations](/influxdb3/clustered/write-data/best-practices/schema-design/).

## Understand the difference between tags and fields

In the [InfluxDB data structure](/influxdb3/clustered/write-data/best-practices/schema-design/#influxdb-data-structure), there are three main “categories” of information–timestamps, tags, and fields. Understanding the difference between what should be a tag and what should be a field is important when designing your schema.

Use the following guidelines to determine what should be tags versus fields:

-   Use tags to store metadata that provides information about the source or context of the data.
-   Use fields to store measured values.
-   Field values typically change over time. Tag values do not.
-   Tag values can only be strings.
-   Field values can be any of the following data types:
    -   Integer
    -   Unsigned integer
    -   Float
    -   String
    -   Boolean

For more information, see [Tags versus fields](/influxdb3/clustered/write-data/best-practices/schema-design/#tags-versus-fields).

## Schema restrictions

InfluxDB enforces the following schema restrictions:

-   You cannot use the same name for a tag and a field in the same table.
-   By default, a table can have up to 250 columns.

For more information, see [InfluxDB schema restrictions](/influxdb3/clustered/write-data/best-practices/schema-design/#schema-restrictions).

## Design for performance

The following guidelines help to ensure write and query performance:

Follow the links below for more detailed information.

-   [Avoid wide schemas](/influxdb3/clustered/write-data/best-practices/schema-design/#avoid-wide-schemas): A wide schema is one with a large number of columns (tags and fields).
-   [Avoid sparse schemas](/influxdb3/clustered/write-data/best-practices/schema-design/#avoid-sparse-schemas): A sparse schema is one where, for many rows, columns contain null values.
-   [Keep table schemas homogenous](/influxdb3/clustered/write-data/best-practices/schema-design/#table-schemas-should-be-homogenous): A homogenous table schema is one where every row has values for all tags and fields.
-   [Use the best data type for your data](/influxdb3/clustered/write-data/best-practices/schema-design/#use-the-best-data-type-for-your-data): Write integers as integers, decimals as floats, and booleans as booleans. Queries against a field that stores integers outperforms a query against string data.

## Design for query simplicity

The following guidelines help to ensure that, when querying data, the schema makes it easy to write queries:

Follow the links below for more detailed information.

-   [Keep table names, tags, and fields simple](/influxdb3/clustered/write-data/best-practices/schema-design/#keep-table-names-tags-and-fields-simple): Use one tag or one field for each data attribute. If your source data contains multiple data attributes in a single parameter, split each attribute into its own tag or field.
-   [Avoid keywords and special characters](/influxdb3/clustered/write-data/best-practices/schema-design/#avoid-keywords-and-special-characters): Reserved keywords or special characters in table names, tag keys, and field keys makes writing queries more complex.

[Optimize your cluster](/influxdb3/clustered/install/optimize-cluster/) [Identify write methods](/influxdb3/clustered/install/optimize-cluster/write-methods/)

#### Related

-   [InfluxDB schema design recommendations](/influxdb3/clustered/write-data/best-practices/schema-design/)