tableInsert / insert into

DolphinDB offers several ways to write to an in-memory table:

• Insert a single row of data with insert into
• Insert multiple rows of data in bulk with function tableInsert
• Insert a table object with function tableInsert

It is not recommended to save data with function append!, as append! returns the schema of a table and unnecessarily increases the network traffic.

The table in the following examples has 4 columns. Their data types are STRING, INT, TIMESTAMP and DOUBLE. The column names are cstring, cint, ctimestamp and cdouble, respectively.

t = table(10000:0,`cstring`cint`ctimestamp`cdouble,[STRING,INT,TIMESTAMP,DOUBLE])
share t as sharedTable

By default, an in-memory table is not shared among sessions. To access it in a different session, share it among sessions with share.

Insert a Single Record with insert into

To insert a single record to a DolphinDB in-memory table, you can use the insert into statement.

Insert Multiple Records with tableInsert

Function tableInsert can save records in batches. If data in Java can be organized as a List, it can be saved with function tableInsert.

public void test_save_TableInsert(List<String> strArray,List<Integer> intArray,List<Long> tsArray,List<Double> dblArray) throws IOException{
    //Construct parameters with arrays
    List<Entity> args = Arrays.asList(new BasicStringVector(strArray),new BasicIntVector(intArray),new BasicTimestampVector(tsArray),new BasicDoubleVector(dblArray));
    conn.run("tableInsert{sharedTable}", args);
}

The example above uses partial application in DolphinDB to embed a table in tableInsert{sharedTable} as a function.

Save BasicTable Objects With Function tableInsert

Function tableInsert can also accept a BasicTable object in Java as a parameter to append data to a table in batches.

public void test_save_table(BasicTable table1) throws IOException {
    List<Entity> args = Arrays.asList(table1);
    conn.run("tableInsert{shareTable}", args);
}

DFS table is recommended by DolphinDB in production environment. It supports snapshot isolation and ensures data consistency. With data replication, DFS tables offers fault tolerance and load balancing.

Save BasicTable Objects With Function tableInsert

dbPath = 'dfs://testDatabase'
tbName = 'tb1'

if(existsDatabase(dbPath)){dropDatabase(dbPath)}
db = database(dbPath,RANGE,2018.01.01..2018.12.31)
db.createPartitionedTable(t,tbName,'ctimestamp')

DolphinDB provides loadTable method to load DFS tables and tableInsert method to append data.

public void test_save_table(String dbPath, BasicTable table1) throws IOException{
    List<Entity> args = new ArrayList<Entity>(1);
    args.add(table1);
    conn.run(String.format("tableInsert{loadTable('%s','tb1')}",dbPath), args);
}