Catatan
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Berlaku untuk:
Databricks SQL Databricks Runtime
Mengembalikan informasi metadata dasar tabel. Informasi metadata mencakup nama kolom, jenis kolom, dan komentar kolom. Secara opsional, Anda dapat menentukan spesifikasi partisi atau nama kolom untuk mengembalikan metadata yang berkaitan dengan partisi atau kolom masing-masing. Dengan tabel Delta, tidak semua bidang dikembalikan.
Metadata dikembalikan dalam formulir laporan atau sebagai dokumen JSON.
Penting
Gunakan DESCRIBE AS JSON untuk menguraikan output secara terprogram. Format laporan non-JSON dapat berubah.
Sintaks
{ DESC | DESCRIBE } [ TABLE ] [ EXTENDED ] table_name { [ PARTITION clause ] | [ column_name ] } [ AS JSON ]
Untuk kompatibilitas FORMATTED dapat ditentukan sebagai sinonim untuk EXTENDED.
Parameter
EXTENDEDJika ditentukan, tampilkan informasi terperinci tentang kolom yang ditentukan, termasuk statistik kolom yang dikumpulkan oleh perintah, dan informasi metadata tambahan (seperti kualifikasi skema, pemilik, dan waktu akses).
-
Mengidentifikasi tabel yang akan dijelaskan. Nama tidak boleh menggunakan spesifikasi temporal atau spesifikasi opsi. Jika tabel tidak dapat ditemukan, Azure Databricks menimbulkan kesalahan TABLE_OR_VIEW_NOT_FOUND .
-
Parameter opsional yang mengarahkan Databricks SQL untuk mengembalikan metadata tambahan untuk partisi bernama.
-
Parameter opsional dengan nama kolom yang perlu dijelaskan. Kolom bersarang saat ini tidak diizinkan untuk ditentukan.
Format JSON didukung untuk kolom individual.
AS JSONBerlaku untuk:
Databricks SQL Databricks Runtime 16.2 dan lebih tinggiSecara opsional mengembalikan metadata tabel sebagai string JSON alih-alih laporan yang dapat dibaca manusia. Gunakan format ini saat mengurai hasil menggunakan program.
Hanya didukung saat format
EXTENDEDditentukan.
Parameter partition_spec dan column_name saling eksklusif dan tidak dapat ditentukan bersama- sama.
Output berformat JSON
Saat AS JSON ditentukan, output dikembalikan sebagai string JSON. Skema berikut didukung:
{
"table_name": "<table_name>",
"catalog_name": "<catalog_name>",
"schema_name": "<schema_name>",
"namespace": ["<schema_name>"],
"type": "<table_type>",
"provider": "<provider>",
"columns": [
{
"name": "<name>",
"type": <type_json>,
"comment": "<comment>",
"nullable": <boolean>,
"default": "<default_val>",
"is_measure": <boolean>, // Included only for measure columns of metric views
}
],
"partition_values": {
"<col_name>": "<val>"
},
"partition_columns": ["col1", "col2"],
"location": "<path>",
"view_text": "<view_text>",
"view_original_text": "<view_original_text>",
"view_schema_mode": "<view_schema_mode>",
"view_catalog_and_namespace": "<view_catalog_and_namespace>",
"view_query_output_columns": ["<col_name>"],
"comment": "<comment>",
"table_properties": {
"property1": "<property1>",
"property2": "<property2>"
},
"statistics": {
"num_rows": <count>,
"size_in_bytes": <bytes>,
"table_change_stats": {
"inserted": <count>,
"deleted": <count>,
"updated": <count>,
"change_percent": <percent_changed_float>
}
},
"storage_properties": {
"property1": "<property1>",
"property2": "<property2>"
},
"serde_library": "<serde_library>",
"input_format": "<input_format>",
"output_format": "<output_format>",
"num_buckets": <num_buckets>,
"bucket_columns": ["<col_name>"],
"sort_columns": ["<col_name>"],
"created_time": "<timestamp_ISO-8601>",
"created_by": "<created_by>",
"last_access": "<timestamp_ISO-8601>",
"partition_provider": "<partition_provider>",
"collation": "<default_collation>", // Available in DBR 16.4 and above
"language": "<language>", // Language such as YAML, included only for metric views
"row_filter": { // Available in DBR 17.0 and above
"filter_function": {
"catalog_name": "<catalog_name>",
"schema_name": "<schema_name>",
"function_name: "<function_name>",
"specific_name": "<specific_name>"
},
"arguments": ["<arg1>", "<arg2>"]
},
"column_masks": [ // Available in DBR 17.0 and above
{"column_name": "<column_name>",
"mask_function": {
"catalog_name": "<catalog_name>",
"schema_name": "<schema_name>",
"function_name: "<function_name>",
"specific_name": "<specific_name>"
},
"arguments": ["<arg1>", "<arg2>"]
}
]
}
Di bawah ini adalah definisi skema untuk <type_json>:
| Jenis SQL | Representasi JSON |
|---|---|
| TINYINT | { "name" : "tinyint" } |
| SMALLINT | { "name" : "smallint" } |
| INT | { "name" : "int" } |
| BIGINT | { "name" : "bigint" } |
| MENGAPUNG | { "name" : "float" } |
| DOBEL | { "name" : "double" } |
| DESIMAL (p, dtk) | { "name" : "decimal", "precision": p, "scale": s } |
| string | { "name" : "string", "collation": "<collation>" } |
| VARCHAR (n) | { "name" : "varchar", "length": n } |
| CHAR(n) | { "name" : "char", "length": n } |
| BINER | { "name" : "binary" } |
| BOOLEAN | { "name" : "boolean" } |
| TANGGAL | { "name" : "date" } |
| TIMESTAMP | { "name" : "timestamp_ltz" } |
| TIMESTAMP_NTZ | { "name" : "timestamp_ntz" } |
| INTERVAL start_unit HINGGA end_unit | { "name" : "interval", "start_unit": "<start_unit>", "end_unit": "<end_unit>" } |
| ARRAY<element_type> | { "name" : "array", "element_type": <type_json>, "element_nullable": <boolean_val> } |
| PETA<key_type, value_type> | { "name" : "map", "key_type": <type_json>, "value_type": <type_json>, "element_nullable": <boolean_val> } |
| STRUCT<field_name ..., ...> | { "name" : "struct", "fields": [ {"name" : "<field_name>", "type" : <type_json>, “nullable”: <boolean_val>, "comment": “<field_comment>”, "default": “<default_val>”}] } |
| VARIAN | { "name" : "variant" } |
Contoh
-- Creates a table `customer`. Assumes current schema is `salesdb`.
> CREATE TABLE customer(
cust_id INT,
state VARCHAR(20),
name STRING COMMENT 'Short name'
)
USING parquet
PARTITIONED BY (state);
> INSERT INTO customer PARTITION (state = 'AR') VALUES (100, 'Mike');
-- Returns basic metadata information for unqualified table `customer`
> DESCRIBE TABLE customer;
col_name data_type comment
----------------------- --------- ----------
cust_id int null
name string Short name
state string null
# Partition Information
# col_name data_type comment
state string null
-- Returns basic metadata information for qualified table `customer`
> DESCRIBE TABLE salesdb.customer;
col_name data_type comment
----------------------- --------- ----------
cust_id int null
name string Short name
state string null
# Partition Information
# col_name data_type comment
state string null
-- Returns additional metadata such as parent schema, owner, access time etc.
> DESCRIBE TABLE EXTENDED customer;
col_name data_type comment
---------------------------- ------------------------------ ----------
cust_id int null
name string Short name
state string null
# Partition Information
# col_name data_type comment
state string null
# Detailed Table Information
Database default
Table customer
Owner <TABLE OWNER>
Created Time Tue Apr 07 22:56:34 JST 2020
Last Access UNKNOWN
Created By <SPARK VERSION>
Type MANAGED
Provider parquet
Location file:/tmp/salesdb.db/custom...
Serde Library org.apache.hadoop.hive.ql.i...
InputFormat org.apache.hadoop.hive.ql.i...
OutputFormat org.apache.hadoop.hive.ql.i...
Partition Provider Catalog
-- Returns partition metadata such as partitioning column name, column type and comment.
> DESCRIBE TABLE EXTENDED customer PARTITION (state = 'AR');
col_name data_type comment
------------------------------ ------------------------------ ----------
cust_id int null
name string Short name
state string null
# Partition Information
# col_name data_type comment
state string null
# Detailed Partition Inform...
Database default
Table customer
Partition Values [state=AR]
Location file:/tmp/salesdb.db/custom...
Serde Library org.apache.hadoop.hive.ql.i...
InputFormat org.apache.hadoop.hive.ql.i...
OutputFormat org.apache.hadoop.hive.ql.i...
Storage Properties [serialization.format=1, pa...
Partition Parameters {transient_lastDdlTime=1586...
Created Time Tue Apr 07 23:05:43 JST 2020
Last Access UNKNOWN
Partition Statistics 659 bytes
# Storage Information
Location file:/tmp/salesdb.db/custom...
Serde Library org.apache.hadoop.hive.ql.i...
InputFormat org.apache.hadoop.hive.ql.i...
OutputFormat org.apache.hadoop.hive.ql.i...
------------------------------ ------------------------------ ----------
-- Returns the metadata for `name` column.
-- Optional `TABLE` clause is omitted and column is fully qualified.
> DESCRIBE customer salesdb.customer.name;
info_name info_value
--------- ----------
col_name name
data_type string
comment Short name
- Returns the table metadata in JSON format.
> DESCRIBE EXTENDED customer AS JSON;
{
"table_name":"customer",
"catalog_name":"spark_catalog",
"schema_name":"default",
"namespace":["default"],
"columns":[
{"name":"cust_id","type":{"name":"integer"},"nullable":true},
{"name":"name","type":{"name":"string"},"comment":"Short name","nullable":true},
{"name":"state","type":{"name":"varchar","length":20},"nullable":true}],
"location": "file:/tmp/salesdb.db/custom...",
"created_time":"2020-04-07T14:05:43Z",
"last_access":"UNKNOWN",
"created_by":"None",
"type":"MANAGED",
"provider":"parquet",
"partition_provider":"Catalog",
"partition_columns":["state"]}
-- The JSON describe of a metric view
> DESCRIBE EXTENDED region_sales_metrics AS JSON;
{
"table_name":"region_sales_metrics",
"catalog_name":"main",
"namespace":["default"],
"schema_name":"default",
"columns":[
{"name":"month","type":{"name":"timestamp_ltz"},"nullable":true},
{"name":"status","type":{"name":"string","collation":"UTF8_BINARY"},"nullable":true},
{"name":"prder_priority","type":{"name":"string","collation":"UTF8_BINARY"},"nullable":true},
{"name":"count_orders","type":{"name":"bigint"},"nullable":false,"is_measure":true},
{"name":"total_revenue","type":{"name":"decimal","precision":28,"scale":2},"nullable":true,"is_measure":true},
{"name":"total_revenue_per_customer","type":{"name":"decimal","precision":38,"scale":12},"nullable":true,"is_measure":true}],
"owner":"alf@melmak.et",
"created_time":"2025-05-18T23:45:25Z",
"last_access":"UNKNOWN",
"created_by":"Spark ",
"type":"METRIC_VIEW",
"comment":"A metric view for regional sales metrics.",
"view_text":"\n version: 0.1\n source: samples.tpch.orders\n filter: o_orderdate > '1990-01-01'\n dimensions:\n - name: month\n expr: date_trunc('MONTH', o_orderdate)\n - name: status\n expr: case\n when o_orderstatus = 'O' then 'Open'\n when o_orderstatus = 'P' then 'Processing'\n when o_orderstatus = 'F' then 'Fulfilled'\n end\n - name: prder_priority\n expr: split(o_orderpriority, '-')[1]\n measures:\n - name: count_orders\n expr: count(1)\n - name: total_revenue\n expr: SUM(o_totalprice)\n - name: total_revenue_per_customer\n expr: SUM(o_totalprice) / count(distinct o_custkey)\n ","language":"YAML","table_properties":{"metric_view.from.name":"samples.tpch.orders","metric_view.from.type":"ASSET","metric_view.where":"o_orderdate > '1990-01-01'"},
"view_creation_spark_configuration":{ ... },
"collation":"UTF8_BINARY"}
MENJELASKAN DETAIL
DESCRIBE DETAIL [schema_name.]table_name
Mengembalikan informasi tentang skema, partisi, ukuran tabel, dan sebagainya. Misalnya, untuk tabel Delta, Anda dapat melihat versi pembaca dan penulis tabel saat ini. Lihat Deskripsi detail tabel Delta Lake untuk skema rinci.