Spatial Engine SQLServer

A spatial engine provides access to a service that can perform spatial operations, one of the available spatial engines is for SQLServer.

There may be performance issues when drawing selections with SQL Server. It's possible that altering the batchsize value for the selection map engine may improve the performance, a value of 50 is recommended.

Weave 2.5.12 has been updated to resolve this issue.

Namespace

urn:com.cohga.server.spatial.geotools#1.0

Tags

spatialengine

Properties

Name	Type	Required	Description
id	string	yes	Unique identifier
dbtype	'sqlserver'	yes	The name of the driver to use, in this case sqlserver
host	string	yes	The hostname or ip address of the SQL Server server
port	number	yes	The port number that the SQL Server instance is running on
database	string	no	The database to be connected to
instance	string	no	The SQLServer instance to be connected to
schema	string	no	The schema used when connecting to the database
user	string	yes	The userid used when connecting to the database
passwd	string	yes	The password used when connecting to the database
namespace	string	no	The namespace prefix
minconnections	integer	no	The minimum number of pooled connection. Default 1
maxconnections	integer	no	The maximum number of open connections. Default 10
validateconnections	boolean	no	Check connection is alive before using it. Default false
fetchsize	integer	no	The number of records read with each iteraction with the dbms. Default 1000
connectiontimeout	integer	no	The number of seconds the connection pool will wait before timing out attempting to get a new connection. Default 20 (seconds)
primarykeymetadatatable	string	no	The optional table containing primary key structure and sequence associations. Can be expressed as 'schema.name' or just 'schema' (if the table name is 'GT_PK_METADATA'). Default none
maxopenpreparedstatements	integer	no	Maximum number of prepared statements kept open and cached for each connection in the pool. Set to 0 to have unbounded caching, to -1 to disable caching. Default 50
geometrymetadatatable	string	no	The options table containing geometry column metadata information.
usenativegeometryserialization	boolean	no	Use native SQL Server serialization, or WKB serialization. Default is false.
forcespatialindexusageviahints	boolean	no	When enabled, spatial filters will be accompained by a WITH INDEX sql hint forcing the usage of the spatial index. Default is false.

Sub-tags

None

Content

None

Examples

Basic SQL Server connection

<spatial:spatialengine id="sqlserver">
  <dbtype>sqlserver</dbtype>
  <host>sqlhost</host>
  <port>1434</port>
  <user>gis</user>
  <passwd>hak0rz</passwd>
  <schema>GIS</schema>
  <minconnection>2</minconnections>
  <validateconnections>true</validateconnections>
</spatial:spatialengine>

Row Identifiers

Weave needs to be able to uniquely identify each row in a particular table, normally it would do this using the primary key of the table, but sometimes a primary key has not been specified so this information must be provided another way.

This can be done by creating a primary key metadata table and populating it with a row for each table that will be exposed to Weave and then setting the primarykeymetadatatable attribute for the spatial engine.

SQL create statement for gt_pk_metadata table

CREATE TABLE GT_PK_METADATA (
  TABLE_SCHEMA varchar(255) NOT NULL,
  TABLE_NAME varchar(255) NOT NULL,
  PK_COLUMN varchar(255) NOT NULL,
  PK_COLUMN_IDX int NOT NULL,
  PK_POLICY varchar(255) NOT NULL,
  PK_SEQUENCE varchar(255),
   UNIQUE(TABLE_SCHEMA, TABLE_NAME, PK_COLUMN),
   CHECK(PK_POLICY IN ('ASSIGNED','SEQUENCE', 'AUTOGENERATED') )
)

Primary Key Metadata

If the primary key for a table can not be determined by Weave directly from the database then the information can be provided by creating a table or directly embedding the information in the spatial engine configuration.

Column	Description
table_schema	Name of the database schema in which the table is located.
table_name	Name of the table to be published
pk_column	Name of a column used to form the feature IDs
pk_column_idx	Index of the column in a multi-column key. In case multi column keys are needed multiple records with the same table schema and table name will be used.
pk_policy	The new value generation policy, used in case a new feature needs to be added in the table ('assigned', 'sequence' or 'autogenerated'). Where: 'sequence' means that the value for the column is generated using a database sequence, and the 'pk_sequence' value must be set. 'autogenerated' means that the value for the column is generated by the database using another method. 'assigned' means that the value for the column is determined by the current maximum value +1, if the column is an integral type, or as a random string if the column is textual.
pk_sequence	The name of the database sequence to be used when generating a new value for the pk_column. The pk_sequence value only need to be set if the pk_policy is 'sequence'.

Using primary key metadata configuration

You can also specify the above information directly in the spatial engine configuration.

Name	Description
name	The table name
schema	The optional table schema
column	The column in the the table that contains the unique id
policy	How the key is generated
sequence	The name of the database sequence to use if the policy is 'sequence'

<spatial:spatialengine id="sqlserver">
  <dbtype>sqlserver</dbtype>
  <host>sqlhost</host>
  <port>1434</port>
  <user>gis</user>
  <passwd>hak0rz</passwd>
  <schema>GIS</schema>
  <minconnection>2</minconnections>
  <validateconnections>true</validateconnections>
  <primarykeymetadata>
    <table schema="dbo" name="park" column="gid" policy="autogenerated"/>
    <table schema="dbo" name="property" column="park_id" type="autogenerated"/>
    <table schema="dbo" name="road" column="objectid" type="autogenerated"/>
  </primarykeymetadata>
</spatial:spatialengine>

Using the geometry metadata table

The SQL server data store can determine the geometry type and native SRID of a particular column only by data inspection, by looking at the first row in the table. Of course this is error prone, and works only if there is data in the table. The administrator can address the above issue by manually creating a geometry metadata table describing each geometry column. Its presence is indicated via the SQL Server datastore connection parameter named geometrymetadatatable (which may be a simple table name or a schema-qualified one). The table has the following structure (the table name is flexible, just specify the one chosen in the data store connection parameter):

Creating geometry metadata table

CREATE TABLE GT_GEOMETRY_METADATA (
   F_TABLE_SCHEMA VARCHAR(30) NOT NULL,
   F_TABLE_NAME VARCHAR(30) NOT NULL,
   F_GEOMETRY_COLUMN VARCHAR(30) NOT NULL,
   COORD_DIMENSION INTEGER,
   SRID INTEGER NOT NULL,
   TYPE VARCHAR(30) NOT NULL,
   UNIQUE(F_TABLE_SCHEMA, F_TABLE_NAME, F_GEOMETRY_COLUMN),
   CHECK(TYPE IN ('POINT','LINESTRING', 'POLYGON', 'COLLECTION', 'MULTIPOINT', 'MULTILINESTRING', 'MULTIPOLYGON', 'GEOMETRY') )
)

When the table is present the store first searches it for information about each geometry column to be classified, and falls back on data inspection only if the table does not contain any information.

The SRID column should contain the EPSG code for the projection that the data for the layer is stored in.

Using geometry metadata configuration

As of Weave 2.5.16 it's possible to specify the information contained in the geometry metadata table directly in the spatial engine configuration.

Name	Description
name	The table name
schema	The optional table schema
type	The geometry type (point, linestring, polygon, multipoint, multilinestring, multipolygon)
srid	The geometry srid
dimension	The geometry dimension

Using geometry metadata configuration

<spatial:spatialengine id="sqlserver">
  <dbtype>sqlserver</dbtype>
  <host>sqlhost</host>
  <port>1434</port>
  <user>gis</user>
  <passwd>hak0rz</passwd>
  <schema>GIS</schema>
  <minconnection>2</minconnections>
  <validateconnections>true</validateconnections>
  <geometrymetadata>
    <table schema="dbo" name="park" type="multipolygon" srid="28355" dimension="2"/>
    <table schema="dbo" name="property" type="polygon" srid="28355" dimension="2"/>
    <table schema="dbo" name="road" type="linestring" srid="28355" dimension="2"/>
  </geometrymetadata>
</spatial:spatialengine>