Where does ActiveMQ store subscriber information?

After subscribing, you will see an entry in the ACTIVEMQ_ACKS table…

SQL> select container,client_id from esb.activemq_acks;

CONTAINER                                CLIENT_ID
---------------------------------------- ----------------------------------------
topic://testTopic                        me
topic://testTopic                        mysubscriber
topic://testTopic                        mysubscriber2

SQL>

Once unsubscribe has been run on the subscriber…

    ConnectionFactory connectionFactory=new ActiveMQConnectionFactory("admin", "admin", "tcp://localhost:61616");
    Connection connection = connectionFactory.createConnection();
    connection.setClientID(args[0]);
    connection.start();
    Session session = connection.createSession(false,Session.AUTO_ACKNOWLEDGE);
    if (args[1].equals("unsubscribe")) {
      session.unsubscribe("testTopic");
      System.out.println("unsubscribed");
      System.exit(0);
    }

…you will no longer see an entry in the ACTIVEMQ_ACKS table…

SQL> select container,client_id from esb.activemq_acks

CONTAINER                                CLIENT_ID
---------------------------------------- ----------------------------------------
topic://testTopic                        mysubscriber
topic://testTopic                        mysubscriber2

SQL>

A database trace will show what is below…

#-------------------------------------------------------------------
2016-05-18 19:03:01.327785
12280 milliseconds since the previous top level execution statement.
LINE# =  1381
DELETE FROM ACTIVEMQ_ACKS WHERE CONTAINER=:1  AND CLIENT_ID=:2  AND SUB_NAME=:3

  select obj#, name, stab#, sobj#, sobjd#, ttab#, tobj#, tobjd#, mflags from rmtab$ where (stab# = :1 or ttab# = :1) order by obj#

  select binaryDefVal, lengthb(binaryDefVal), guard_id from ecol$ where tabobj# = :1 and colnum = :2

#-------------------------------------------------------------------
2016-05-18 19:03:01.336822
9 milliseconds since the previous top level execution statement.
LINE# =  1404
SELECT COUNT(*) FROM ACTIVEMQ_MSGS M, ACTIVEMQ_ACKS D  WHERE D.CONTAINER=:1  AND D.CLIENT_ID=:2  AND D.SUB_NAME=:3  AND M.CONTAINER=D.CONTAINER      AND M.ID >          ( SELECT LAST_ACKED_ID FROM ACTIVEMQ_ACKS           WHERE CONTAINER=D.CONTAINER AND CLIENT_ID=D.CLIENT_ID           AND SUB_NAME=D.SUB_NAME )

#-------------------------------------------------------------------

…with the following for bind variable values when the backing store is an Oracle database…

BINDS #139635352651880:
 Bind#0
  oacdty=01 mxl=128(68) mxlc=00 mal=00 scl=00 pre=00
  oacflg=03 fl2=1000010 frm=01 csi=873 siz=288 off=0
  kxsbbbfp=7eff63981148  bln=128  avl=17  flg=05
  value="topic://testTopic"
 Bind#1
  oacdty=01 mxl=32(08) mxlc=00 mal=00 scl=00 pre=00
  oacflg=03 fl2=1000010 frm=01 csi=873 siz=0 off=128
  kxsbbbfp=7eff639811c8  bln=32  avl=02  flg=01
  value="me"
 Bind#2
  oacdty=01 mxl=128(36) mxlc=00 mal=00 scl=00 pre=00
  oacflg=03 fl2=1000010 frm=01 csi=873 siz=0 off=160
  kxsbbbfp=7eff639811e8  bln=128  avl=09  flg=01
  value="testTopic"