5.8 KiB
The underlying query engine for the InfluxDB SQL implementation,
DataFusion, provides commands
that return metadata related to your data schema.
To access this information, use the SHOW TABLES, SHOW COLUMNS, and
SHOW ALL commands or query views in the ISO SQL
information_schema schema.
In the context of InfluxDB, a measurement is represented as a table. Time, tags, and fields are each represented by columns in a table.
SHOW TABLES
Returns information about tables (measurements) in an InfluxDB bucket.
SHOW TABLES
You can also query the information_schema.tables view:
SELECT * FROM information_schema.tables
Example SHOW TABLES output
Measurements are those that use the iox table schema.
| table_catalog | table_schema | table_name | table_type |
|---|---|---|---|
| public | iox | home | BASE TABLE |
| public | system | queries | BASE TABLE |
| public | information_schema | tables | VIEW |
| public | information_schema | views | VIEW |
| public | information_schema | columns | VIEW |
| public | information_schema | df_settings | VIEW |
SHOW COLUMNS
Returns information about the schema of a table (measurement) in an InfluxDB bucket.
SHOW COLUMNS FROM example_table
You can also query the information_schema.columns view:
SELECT
table_catalog,
table_schema,
table_name,
column_name,
data_type,
is_nullable
FROM information_schema.columns
WHERE table_name = 'example_table'
Example SHOW COLUMNS output
| table_catalog | table_schema | table_name | column_name | data_type | is_nullable |
|---|---|---|---|---|---|
| public | iox | home | co | Int64 | YES |
| public | iox | home | hum | Float64 | YES |
| public | iox | home | room | Dictionary(Int32, Utf8) | YES |
| public | iox | home | temp | Float64 | YES |
| public | iox | home | time | Timestamp(Nanosecond, None) | NO |
SHOW ALL
Returns the configuration options of the current session.
SHOW ALL
You can also query the information_schema.df_settings view:
SELECT * FROM information_schema.df_settings
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{{% expand "View SHOW ALL example output" %}}
| name | setting |
|---|---|
| datafusion.catalog.create_default_catalog_and_schema | true |
| datafusion.catalog.default_catalog | public |
| datafusion.catalog.default_schema | iox |
| datafusion.catalog.format | |
| datafusion.catalog.has_header | false |
| datafusion.catalog.information_schema | true |
| datafusion.catalog.location | |
| datafusion.execution.batch_size | 8192 |
| datafusion.execution.coalesce_batches | true |
| datafusion.execution.collect_statistics | false |
| datafusion.execution.parquet.enable_page_index | false |
| datafusion.execution.parquet.metadata_size_hint | |
| datafusion.execution.parquet.pruning | true |
| datafusion.execution.parquet.pushdown_filters | true |
| datafusion.execution.parquet.reorder_filters | true |
| datafusion.execution.parquet.skip_metadata | true |
| datafusion.execution.target_partitions | 4 |
| datafusion.execution.time_zone | +00:00 |
| datafusion.explain.logical_plan_only | false |
| datafusion.explain.physical_plan_only | false |
| datafusion.optimizer.enable_round_robin_repartition | true |
| datafusion.optimizer.filter_null_join_keys | false |
| datafusion.optimizer.hash_join_single_partition_threshold | 1048576 |
| datafusion.optimizer.max_passes | 3 |
| datafusion.optimizer.prefer_hash_join | true |
| datafusion.optimizer.repartition_aggregations | true |
| datafusion.optimizer.repartition_file_min_size | 10485760 |
| datafusion.optimizer.repartition_file_scans | true |
| datafusion.optimizer.repartition_joins | true |
| datafusion.optimizer.repartition_sorts | false |
| datafusion.optimizer.repartition_windows | true |
| datafusion.optimizer.skip_failed_rules | true |
| datafusion.optimizer.top_down_join_key_reordering | true |
| datafusion.sql_parser.enable_ident_normalization | true |
| datafusion.sql_parser.parse_float_as_decimal | false |
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