sys.column_store_dictionaries (Transact-SQL)
Applies to: SQL Server 2012 (11.x) and later Azure SQL Managed Instance
Contains a row for each dictionary used in xVelocity memory optimized columnstore indexes. Dictionaries are used to encode some, but not all data types, therefore not all columns in a columnstore index have dictionaries. A dictionary can exist as a primary dictionary (for all segments) and possibly for other secondary dictionaries used for a subset of the column's segments.
Column name | Data type | Description |
---|---|---|
hobt_id | bigint | ID of the heap or B-tree index (HoBT) for the table that has this columnstore index. |
column_id | int | ID of the columnstore column starting with 1. The first column has ID = 1, the second column has ID = 2, etc. |
dictionary_id | int | There can be two kinds of dictionaries, global and local, associated with a column segment. A dictionary_id of 0 represents the global dictionary that is shared across all column segments (one for each row group) for that column. |
version | int | Version of the dictionary format. |
type | int | Dictionary type: 1 - Hash dictionary containing int values 2 - Not used 3 - Hash dictionary containing string values 4 - Hash dictionary containing float values For more information about dictionaries, see Columnstore Indexes Guide. |
last_id | int | The last data ID in the dictionary. |
entry_count | bigint | Number of entries in the dictionary. |
on_disk_size | bigint | Size of dictionary in bytes. |
partition_id | bigint | Indicates the partition ID. Is unique within a database. |
Permissions
Requires VIEW DEFINITION
permission on the table. The following columns return null unless the user also has SELECT
permission: last_id, entry_count, data_ptr.
The visibility of the metadata in catalog views is limited to securables that a user either owns, or on which the user was granted some permission. For more information, see Metadata Visibility Configuration.
See Also
Object Catalog Views (Transact-SQL)
Catalog Views (Transact-SQL)
Querying the SQL Server System Catalog FAQ
sys.columns (Transact-SQL)
sys.all_columns (Transact-SQL)
sys.computed_columns (Transact-SQL)
Columnstore Indexes Guide
Columnstore Indexes Guide
sys.column_store_segments (Transact-SQL)
Σχόλια
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