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Describe Database
DESCRIBE DATABASE shows the name of the database, its comment (if one has been set), and its root location on the filesystem. The uses of SCHEMA and DATABASE are interchangeable – they mean the same thing. DESCRIBE SCHEMA is added in Hive 0.15 (HIVE-8803). EXTENDED also shows the database properties. Describe Table/View/ColumnThere are two formats for the describe table/view/column syntax, depending on whether or not the database is specified. If the database is not specified, the optional column information is provided after a dot:
DESCRIBE shows the list of columns including partition columns for the given table. If the EXTENDED keyword database is specified then it will show all the metadata for the table in Thrift serialized form. This is generally only useful for debugging and not for general use. If the FORMATTED keyword is specified, then it will show the metadata in a tabular format. Note: DESCRIBE EXTENDED shows the number of rows only if statistics were gathered when the data was loaded (see Newly Created Tables), and if the Hive CLI is used instead of a Thrift client or Beeline. HIVE-6285 will address this issue. Although ANALYZE TABLE gathers statistics after the data has been loaded (see Existing Tables), it does not currently provide information about the number of rows. , the optional column information is provided after a space:
DESCRIBE shows the list of columns including partition columns for the given table. If the EXTENDED keyword is specified then it will show all the metadata for the table in Thrift serialized form. This is generally only useful for debugging and not for general use. If the FORMATTED keyword is specified, then it will show the metadata in a tabular format. Note: DESCRIBE EXTENDED shows the number of rows only if statistics were gathered when the data was loaded (see Newly Created Tables), and if the Hive CLI is used instead of a Thrift client or Beeline. HIVE-6285 will address this issue. Although ANALYZE TABLE gathers statistics after the data has been loaded (see Existing Tables), it does not currently provide information about the number of rows. If a table has a complex column then you can examine the attributes of this column by specifying table_name.complex_col_name (and field_name for an element of a struct, '$elem$' for array element, '$key$' for map key, and '$value$' for map value). You can If a table has a complex column then you can examine the attributes of this column by specifying table_name.complex_col_name (and '$elem$' for array element, '$key$' for map key, and '$value$' for map value). You can specify this recursively to explore the complex column type. For a view, DESCRIBE EXTENDED or FORMATTED can be used to retrieve the view's definition. Two relevant attributes are provided: both the original view definition as specified by the user, and an expanded definition used internally by Hive.
Display Column Statistics
ANALYZE TABLE table_name COMPUTE STATISTICS FOR COLUMNS will compute column statistics for all columns in the specified table (and for all partitions if the table is partitioned). To view the gathered column statistics, the following statements can be used:
Display Column Statistics
ANALYZE TABLE table_name COMPUTE STATISTICS FOR COLUMNS will compute column statistics for all columns in the specified table (and for all partitions if the table is partitioned). To view the gathered column statistics, the following statements can be used:
See Statistics in Hive: Existing Tables for more information about the ANALYZE TABLE command. Describe PartitionThere are two formats for the describe partition syntax, depending on whether or not the database is specified. If the database is not specified, the optional column information is provided after a dot:
See Statistics in Hive: Existing Tables for more information about the ANALYZE TABLE command. Describe PartitionIf the database is specified, the optional column information is provided after a space:
This statement lists metadata for a given partition. The output is similar to that of DESCRIBE table_name. Presently, the column information associated with a particular partition is not used while preparing plans. As of Hive 1.2 (HIVE-10307), the partition column values specified in partition_spec are type validated, converted and normalized to their column types when hive.typecheck.on.insert is set to true (default). These values can be number literals.
Hive 2.0+: Syntax Change
Warning: The new syntax could break current scripts.
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- HCatalog DDL in the HCatalog manual
- WebHCat DDL Resources in the WebHCat manual