167 lines
4.8 KiB
Markdown
167 lines
4.8 KiB
Markdown
---
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title: InfluxQL SHOW statements
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description: >
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Use InfluxQL `SHOW` statements to query schema information from a database.
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menu:
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influxdb_clustered:
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name: SHOW statements
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identifier: influxql-show-statements
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parent: influxql-reference
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weight: 207
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list_code_example: |
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```sql
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SHOW [RETENTION POLICIES | MEASUREMENTS | FIELD KEYS | TAG KEYS | TAG VALUES]
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```
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related:
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- /influxdb/clustered/query-data/influxql/explore-schema/
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---
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Use InfluxQL `SHOW` statements to query schema information from a database.
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- [SHOW RETENTION POLICIES](#show-retention-policies)
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- [SHOW MEASUREMENTS](#show-measurements)
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- [SHOW FIELD KEYS](#show-field-keys)
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- [SHOW TAG KEYS](#show-tag-keys)
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- [SHOW TAG VALUES](#show-tag-values)
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## SHOW RETENTION POLICIES
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Use the `SHOW RETENTION POLICIES` statement to list retention policies associated
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with a database.
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Each database has a single retention policy--`autogen`.
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{{% note %}}
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In {{< product-name >}}, retention policies are not part of the
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data structure but are expected by InfluxQL and used in fully-qualified measurements
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in the [`FROM` clause](/influxdb/clustered/reference/influxql/select/#from-clause).
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The data returned for each retention policy does not represent the actual
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retention-related attributes of the database. The values are placeholder values
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meant only for InfluxQL feature parity.
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For information about database data retention, see
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[List databases](/influxdb/clustered/admin/databases/list/).
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{{% /note %}}
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```sql
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SHOW RETENTION POLICIES [ON <database-name>]
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```
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#### Examples
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```sql
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-- Show retention policies in the database specified in the query request
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SHOW RETENTION POLICIES
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-- Show retention policies in a specific database
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SHOW RETENTION POLICIES ON "example-database"
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```
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## SHOW MEASUREMENTS
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Use the `SHOW MEASUREMENTS` statement to list measurements in a database.
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```sql
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SHOW MEASUREMENTS [with_measurement_clause] [where_clause] [limit_clause] [offset_clause]
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```
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#### Examples
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```sql
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-- Show all measurements
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SHOW MEASUREMENTS
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-- Show measurements where region tag = 'uswest' AND host tag = 'serverA'
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SHOW MEASUREMENTS WHERE "region" = 'uswest' AND "host" = 'serverA'
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-- Show measurements that start with 'h2o'
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SHOW MEASUREMENTS WITH MEASUREMENT =~ /h2o.*/
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```
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## SHOW FIELD KEYS
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Use the `SHOW FIELD KEYS` statement to list all field keys in a measurement.
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```sql
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SHOW FIELD KEYS [from_clause]
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```
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#### Examples
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```sql
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-- Show field keys and field value data types from all measurements
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SHOW FIELD KEYS
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-- Show field keys and field value data types from specified measurement
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SHOW FIELD KEYS FROM "cpu"
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```
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## SHOW TAG KEYS
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Use the `SHOW TAG KEYS` statement to list tag keys in a measurement.
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```sql
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SHOW TAG KEYS [from_clause] [where_clause] [limit_clause] [offset_clause]
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```
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#### Examples
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```sql
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-- Show all tag keys
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SHOW TAG KEYS
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-- Show all tag keys from the cpu measurement
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SHOW TAG KEYS FROM "cpu"
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-- Show all tag keys from the cpu measurement where the region key = 'uswest'
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SHOW TAG KEYS FROM "cpu" WHERE "region" = 'uswest'
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-- Show all tag keys where the host key = 'serverA'
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SHOW TAG KEYS WHERE "host" = 'serverA'
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```
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## SHOW TAG VALUES
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Use the `SHOW TAG VALUES` statement to list values of specified tags in a database.
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```sql
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SHOW TAG VALUES [from_clause] WITH KEY = <tag-expression> [where_clause] [limit_clause] [offset_clause]
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```
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By default, the `SHOW TAG VALUES` statement only returns unique tag values from
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**the last day**. To modify the time range, include
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[`WHERE` clause with a time-based predicate](/influxdb/clustered/reference/influxql/where/#time-ranges).
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{{% note %}}
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#### Include a FROM clause
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We strongly recommend including a `FROM` clause with the `SHOW TAG VALUES`
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statement that specifies 1-50 tables to query.
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Without a `FROM` clause, the InfluxDB query engine must read data from all
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tables and return unique tag values from each.
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Depending on the number of tables in your database and the number of unique tag
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values in each table, excluding a `FROM` clause can result in poor query performance,
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query timeouts, or unnecessary resource allocation that may affect other queries.
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{{% /note %}}
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#### Examples
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```sql
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-- Show tag values from the cpu measurement for the region tag
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SHOW TAG VALUES FROM "cpu" WITH KEY = "region"
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-- Show tag values from the cpu measurement for the region tag for a custom time range
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SHOW TAG VALUES FROM "cpu" WITH KEY = "region" WHERE time > -7d
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-- Show tag values from multiple measurements for the region tag
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SHOW TAG VALUES FROM "cpu", "memory", "disk" WITH KEY = "region"
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-- Show tag values from the cpu measurement for all tag keys that do not include the letter c
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SHOW TAG VALUES FROM "cpu" WITH KEY !~ /.*c.*/
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-- Show tag values from the cpu measurement for region & host tag keys where service = 'redis'
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SHOW TAG VALUES FROM "cpu" WITH KEY IN ("region", "host") WHERE "service" = 'redis'
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```
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