Java

Insert

Use the following code to insert an object to GreptimeDB:

java

TableSchema tableSchema = TableSchema.newBuilder(TableName.with("db_name", "monitor"))
    .semanticTypes(SemanticType.Tag, SemanticType.Timestamp, SemanticType.Field, SemanticType.Field)
    .dataTypes(ColumnDataType.String, ColumnDataType.Int64, ColumnDataType.Float64, ColumnDataType.Float64)
    .columnNames("host", "ts", "cpu", "memory")
    .build();
WriteRows rows = WriteRows.newBuilder(tableSchema).build();
rows.insert("127.0.0.1", System.currentTimeMillis(), 0.1, null)
    .insert("127.0.0.2", System.currentTimeMillis(), 0.3, 0.5)
    .finish();
CompletableFuture<Result<WriteOk, Err>> writeFuture = greptimeDB.write(rows);
writeFuture.whenComplete((result, throwable) -> {
    if (throwable != null) {
        throwable.printStackTrace();
    } else {
        System.out.println(result);
    }
});

To begin, we must create a TableSchema and then use it to construct a WriteRows object. Since the TableSchema can be reused, caching it can prevent unnecessary construction.

Once the WriteRows object is created, data can be added to it. However, this data is only stored in memory and has not yet been sent to the server. To insert multiple rows efficiently, we use batch insertion. Once all desired data has been added to the WriteRows, remember to call its finish method before sending it to the server.

After calling the write method on our completed WriteRows, a future will be returned which allows us to obtain write results through its callback function.

Write API

java

/**
 * Write a single table multi rows data to database.
 *
 * @param rows rows with one table
 * @param ctx  invoke context
 * @return write result
 */
CompletableFuture<Result<WriteOk, Err>> write(WriteRows rows, Context ctx);