sys-column-store-dictionaries-transact-sql.md

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sys.column_store_dictionaries (Transact-SQL)

[!INCLUDEtsql-appliesto-ss2012-xxxx-xxxx-xxx_md]

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_disc_size	bigint	Size of dictionary in bytes.
partition_id	bigint	Indicates the partition ID. Is unique within a database.

Permissions

All columns require at least VIEW DEFINITION permission on the table. The following columns return null unless the user also has SELECT permission: last_id, entry_count, data_ptr.

[!INCLUDEssCatViewPerm] 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)