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FAQ: What is the st_geometry_index table?

Question

What is the st_geometry_index table?

Answer

This table holds the spatial index information for an st_geometry column. The spatial index for an st_geometry type is a domain index referred to in the CREATE INDEX statement. The table also maintains information about the statistics of the domain index and spatial attribute which are used by the Oracle optimizer for determining the best access path for a query involving a spatial operator.

The following is a list of each attribute and its description:

OWNER NVARCHAR2(32)
Schema owner.

TABLE_NAME NVARCHAR2(32)
Unqualified table name.

COLUMN_NAME NVARCHAR2(32)
Name of the geometry column.

INDEX_ID NUMBER(38) NOT NULL
Uniquely identifies the domain index.

GRID SDE.SP_GRID_INFO
Grid type containing multilevel integer grid information SP_GRID_INFO is a GRID_TYPE column object consisting of three NUMBER grid values.

SRID NUMBER(38) NOT NULL
SRID and spatial reference information.

COMMIT_INT NUMBER(38)
DML commit interval for spatial index rows; the number of rows affected before issuing a COMMIT. The default value is 1000.

VERSION NUMBER(38)
Domain index version number.

STATUS NVARCHAR2(10)
Describes the index status; 1 = Active or 0 = Disabled. Loading can disable the index for performance reasons. The default is Active.

INDEX_NAME NVARCHAR2(30)
Name of the st_spatial_index (domain index).

UNIQUENESS VARCHAR2(9)
Indicates weather the domain index is UNIQUE or NONUNIQUE.

DISTINCT_KEYS NUMBER
Number of distinct domain index keys.

BLEVEL NUMBER
Depth of the domain index from its root block to its leaf blocks.

LEAF_BLOCKS NUMBER
Number of leaf blocks for the domain index.

CLUSTERING_FACTOR NUMBER
Indicates the amount of order of the rows in the table based on the values of the index. If the value is near the number of blocks, then the table is very well ordered. In this case, the index entries in a single leaf block tend to point to rows in the same data blocks. If the value is near the number of rows, then the table is very randomly ordered. In this case, it is unlikely that index entries in the same leaf block point to rows in the same data blocks.

DENSITY NUMBER
Average number of features per grid cell.

NUM_ROWS NUMBER
Number of rows for the table containing the st_geometry and st_spatial_index.

NUM_NULLS NUMBER
Number of NULL st_geometry attribute values for the table containing the st_geometry and st_spatial_index.

SAMPLE_SIZE NUMBER
Sample size used when collecting statistics (DBMS_STATS).

LAST_ANALYZED DATE
Date on which this table was most recently analyzed.

USER_STATS VACHAR2(3)
Indicates whether statistics were entered directly by the user (YES) or not (NO).

ST_FUNCS SDE.ST_FUNCS_ARRAY
Indicates user defined operator selectivity and cost values. When set, defined values override derivied selectivity and system defined operator cost.