14.12.1 Loading a PgxFrame from a Database

PgxFrame(s) can also be loaded from relational tables in an Oracle database. Each column of the relational table will correspond to a column in the loaded frame. When loading PgxFrames from the database, the default behavior is to detect what columns the table has, and to load them all. If not specified explicitly, the connection details of the current user and session are used and the columns are detected automatically.

The following describes the steps to load a PgxFrame from a database table:

1. Create a Session and an Analyst.
   Creating a Session and an Analyst Using JShell

   cd /opt/oracle/graph/
   ./bin/opg4j
   // starting the shell will create an implicit session and analyst
   opg4j> import static oracle.pgx.api.frames.functions.ColumnRenaming.renaming
   opg4j> import static oracle.pgx.api.frames.schema.ColumnDescriptor.columnDescriptor
   opg4j> import oracle.pgx.api.frames.schema.*
   opg4j> import oracle.pgx.api.frames.schema.datatypes.*

   Creating a Session and an Analyst Using Java

   import oracle.pgx.api.*;
   import oracle.pgx.api.frames.*;
   import oracle.pgx.api.frames.functions.*;
   import oracle.pgx.api.frames.schema.*;
   import oracle.pgx.api.frames.schema.datatypes.*;
   import static oracle.pgx.api.frames.functions.ColumnRenaming.renaming;
   import static oracle.pgx.api.frames.schema.ColumnDescriptor.columnDescriptor;
   
   PgxSession session = Pgx.createSession("my-session");
   Analyst analyst = session.createAnalyst();

   Creating a Session and an Analyst Using Python

   session = pypgx.get_session(session_name="my-session")
   analyst = session.create_analyst()

2. Load a PgxFrame.
   Loading a PgxFrame Using JShell

   opg4j> var exampleFrame = session.readFrame().
       db().
       name("framename").      // name of the frame
       tablename("tablename"). // name of the table from where the data must be loaded
       connections(16).        // indicates that 16 connections can be used to load in parallel
       load();

   Loading a PgxFrame Using Java

   PgxFrame exampleFrame = session.readFrame()
       .db()
       .name("framename")      // name of the frame
       .tablename("tablename") // name of the table from where the data must be loaded
       .connections(16)        // indicates that 16 connections can be used to load in parallel
       .load();

3. If only a subset of the columns must be loaded, then you must specify the columns with FrameReader.columns().
   Loading a PgxFrame for a Subset of Columns Using JShell

   // You must specify jdbc connection, keystore and the columns to load
   opg4j> session.registerKeystore("keystore", pathToKeystore, keystorePassword)
   opg4j> var exampleFrame = session.readFrame().
       db().
       name("framename").
       tablename("tablename").      // name of the table from where the data must be loaded
       jdbcUrl("jdbcUrl").
       username("user").
       keystoreAlias("keytore").
       owner("owner").              // necessary if the table is owned by another user
       connections(16).             // indicates that 16 connections can be used to load in parallel
       columns(exampleFrameSchema). // columns to load
       load();

   Loading a PgxFrame for a Subset of Columns Using Java

   import oracle.pgx.api.frames.schema.datatypes.DataTypes;
   import oracle.pgx.api.frames.schema.ColumnDescriptor;
   // You must specify jdbc connection, keystore and the columns to load
   session.registerKeystore("keystore", pathToKeystore, keystorePassword)
   PgxFrame exampleFrame = session.readFrame()
       .db()
       .name("framename")
       .tablename("tablename")      // name of the table from where the data must be loaded
       .jdbcUrl("jdbcUrl")
       .username("user")
       .keystoreAlias("keytore")
       .owner("owner")              // necessary if the table is owned by another user
       .connections(16)             // indicates that 16 connections can be used to load in parallel
       .columns(exampleFrameSchema) // columns to load
       .load();

You can also create a graph from the PgxFrame(s). See Creating a Graph from Multiple PgxFrame Objects for more information.