Usage examples for the spatio-temporal trajectory feature-Lindorm(Lindorm)-阿里云帮助中心

This topic shows you how to download, compile, and run the Lindorm spatiotemporal trajectory sample code. The sample writes and queries Automatic Identification System (AIS) vessel trajectory data using the Moving Object Database (MOD) API.

Download and compile the sample code

Download the sample package: lindorm-mod-sample
Decompress the package, then navigate to the lindorm-sample directory.
Compile the source code:
- -Dmaven.test.skip=true: skips unit tests to speed up the build
- -s ../settings.xml: uses the bundled Maven settings file, which points to the required dependencies
```
mvn install -Dmaven.test.skip=true -s ../settings.xml
```
After the build completes, the compiled JAR lindorm-mod-sample-1.0.0.jar appears in the target/ directory.

How it works

All write and query operations use the same run command. The behavior is controlled entirely by mod_template.json:

java -jar target/lindorm-mod-sample-1.0.0.jar src/main/resources/template/mod_template.json

Edit mod_template.json to switch between write and query modes, or to adjust parameters. The sample file at src/main/resources/template/mod_template.json serves as a starting point.

Write trajectory data

Configure mod_template.json for a write operation:

{
  "operation" : "WRITE",
  "zk_address" : "your_zk_address",
  "catalog" : "example",
  "schema" : "traj",
  "enable_secondary_index" : "true",
  "print_info": "false",
  "enabled_indices" : "id,xz2t",
  "primary_index" : "id",
  "thread_num": 8,
  "input_dir": "path_to_repository/lindorm-sample/src/main/resources/data/traj"
}

Parameters

Parameter	Description	Example
`operation`	Operation type: `WRITE` or `QUERY`	`WRITE`
`zk_address`	ZooKeeper address for your Lindorm instance	`192.168.0.1:2181`
`catalog`	Catalog (database namespace) to write data into	`example`
`schema`	Table name for storing trajectory data	`traj`
`enable_secondary_index`	Set to `true` to enable secondary indexes	`true`
`enabled_indices`	Comma-separated list of index types to create. See Create index tables for available types	`id,xz2t`
`primary_index`	Index to use as the primary index	`id`
`print_info`	Set to `true` to print detailed write progress. Useful for debugging	`false`
`thread_num`	Number of concurrent threads for writing. Default: `1`	`8`
`input_dir`	Path to the directory containing AIS trajectory point data files	`path_to_repository/lindorm-sample/src/main/resources/data/traj`

Trajectory splitting

The sample splits trajectory objects into segments before indexing. Four split policies are available:

Policy	Splits when...
`BY_COUNT`	The segment reaches the specified number of trajectory points (default: 50 points per segment)
`BY_DURATION`	The segment reaches the specified time duration
`BY_DISTANCE`	The segment reaches the specified distance
`BY_ANGLE`	The heading angle change exceeds the specified threshold

To change the active policy or threshold, edit SplitConfigs in MOD.java.

Run the write operation:

java -jar target/lindorm-mod-sample-1.0.0.jar src/main/resources/template/mod_template.json

Query trajectory data

Configure mod_template.json for a query operation:

{
  "operation" : "QUERY",
  "zk_address" : "your_zk_address",
  "catalog" : "example",
  "schema" : "traj",
  "predicate" : "INTERSECTS(geom, POLYGON ((-76 28, -74 28, -74 30, -76 30, -76 28))) and traj_start_time >= 1549510271 AND traj_start_time <= 1549583941",
  "return_complete_trajectory" : "false",
  "print_results" : "true"
}

Parameters

Parameter	Description	Example
`operation`	Operation type	`QUERY`
`zk_address`	ZooKeeper address for your Lindorm instance	`192.168.0.1:2181`
`catalog`	Catalog to query	`example`
`schema`	Table name to query	`traj`
`predicate`	Query filter combining a spatial predicate and a time range. The spatial predicate uses `INTERSECTS(geom, <WKT geometry>)`. The time range uses Unix timestamps	See example above
`return_complete_trajectory`	When `false` (default), returns only the trajectory segments that match the query conditions. Set to `true` to return the complete trajectory data	`false`
`print_results`	Set to `true` to print query results to stdout	`true`

Run the query:

java -jar target/lindorm-mod-sample-1.0.0.jar src/main/resources/template/mod_template.json

The output lists the trajectory objects that intersect the specified geographic area and time range. Each returned object corresponds to a trajectory segment — or the full trajectory if return_complete_trajectory is true — that matches the predicate.

What's next

Create index tables — learn about the available index types, including XZ2T, and when to use each