90 lines
3.4 KiB
Markdown
90 lines
3.4 KiB
Markdown
---
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title: InfluxDB system tables
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description: >
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InfluxDB system measurements contain time series data used by and generated from the
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InfluxDB internal monitoring system.
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menu:
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influxdb_cloud_dedicated:
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name: System tables
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parent: InfluxDB internals
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weight: 103
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influxdb/cloud-dedicated/tags: [tables, information schema]
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related:
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- /influxdb/cloud-dedicated/reference/sql/information-schema/
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---
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InfluxDB system measurements contain time series data used by and generated from the
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InfluxDB internal monitoring system.
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Each {{% product-name %}} namespace includes the following system measurements:
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<!-- TOC -->
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- [system.queries measurement](#systemqueries-measurement)
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- [system.queries schema](#systemqueries-schema)
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## system.queries measurement
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The `system.queries` measurement stores log entries for queries executed for the provided namespace (database) on the node that is currently handling queries.
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```python
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from influxdb_client_3 import InfluxDBClient3
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client = InfluxDBClient3(token = DATABASE_TOKEN,
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host = HOSTNAME,
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org = '',
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database=DATABASE_NAME)
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client.query('select * from home')
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reader = client.query('''
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SELECT *
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FROM system.queries
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WHERE issue_time >= now() - INTERVAL '1 day'
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AND query_text LIKE '%select * from home%'
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''',
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language='sql',
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headers=[(b"iox-debug", b"true")],
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mode="reader")
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print("# system.queries schema\n")
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print(reader.schema)
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```
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<!--pytest-codeblocks:expected-output-->
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`system.queries` has the following schema:
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```python
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# system.queries schema
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issue_time: timestamp[ns] not null
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query_type: string not null
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query_text: string not null
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completed_duration: duration[ns]
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success: bool not null
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trace_id: string
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```
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_When listing measurements (tables) available within a namespace, some clients and query tools may include the `queries` table in the list of namespace tables._
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`system.queries` reflects a process-local, in-memory, namespace-scoped query log.
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The query log isn't shared across instances within the same deployment.
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While this table may be useful for debugging and monitoring queries, keep the following in mind:
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- Records stored in `system.queries` are volatile.
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- Records are lost on pod restarts.
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- Queries for one namespace can evict records from another namespace.
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- Data reflects the state of a specific pod answering queries for the namespace----the log view is scoped to the requesting namespace and queries aren't leaked across namespaces.
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- A query for records in `system.queries` can return different results depending on the pod the request was routed to.
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**Data retention:** System data can be transient and is deleted on pod restarts.
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The log size per instance is limited and the log view is scoped to the requesting namespace.
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### system.queries schema
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- **system.queries** _(measurement)_
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- **fields**:
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- **issue_time**: timestamp when the query was issued
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- **query_type**: type (syntax: `sql`, `flightsql`, or `influxql`) of the query
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- **query_text**: query statement text
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- **success**: execution status (boolean) of the query
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- **completed_duration**: time (duration) that the query took to complete
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- **trace_id**: trace ID for debugging and monitoring events
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