oracle11g - 全表スキャンを回避 - 最初の行のみを抽出

Question

条件が満たされたときに最初の (ランダムな) 行のみを抽出するクエリを作成しようとしています。

-- Create table
create table TRANSACTIONS_SAMPLE
(
  institution_id               NUMBER(5) not null,
  id                           NUMBER(10) not null,
  partitionkey                 NUMBER(10) default 0 not null,
  cardid                       NUMBER(10),
  accountid                    NUMBER(10),
  batchid                      NUMBER(10) not null,
  amt_bill                     NUMBER(16,3),
  load_date                    DATE not null,
  trxn_date                    DATE not null,
  single_msg_flag              NUMBER(5),
  authaccounttype              VARCHAR2(2 BYTE),
  originator                   VARCHAR2(50),
  amount                       NUMBER(16,3) default 0.000 not null,
  embeddedfee                  NUMBER(16,3) default 0.000 not null,,
  valuedate                    DATE,
  startofinterest              DATE,
  minduevaluedate              DATE,
  postdate                     DATE,
  posttimestamp                DATE,
  Status                       CHAR(4 BYTE) default 'NEW' not null,
)
partition by list (PARTITIONKEY)
(
  partition 0002913151 values (1234567)
    tablespace LIVE
    pctfree 10
    initrans 16
    maxtrans 255
    storage
    (
      initial 8M
      next 1M
      minextents 1
      maxextents unlimited
    )
);

-- Create/Recreate indexes 
create index TRANSACTIONS_SAMPLEI01 on TRANSACTIONS_SAMPLE (ACCOUNTID)
  local;
create index TRANSACTIONS_SAMPLEI02 on TRANSACTIONS_SAMPLE (LOAD_DATE)
  local;
create index TRANSACTIONS_SAMPLEI03 on TRANSACTIONS_SAMPLE (BATCHID)
  local;
create index TRANSACTIONS_SAMPLEI04 on TRANSACTIONS_SAMPLE (POSTDATE)
  local;
create index TRANSACTIONS_SAMPLEI05 on TRANSACTIONS_SAMPLE (POSTTIMESTAMP)
  local;
create index TRANSACTIONS_SAMPLEI06 on TRANSACTIONS_SAMPLE (STATUS, PARTITIONKEY)
  local;
create index TRANSACTIONS_SAMPLEI07 on TRANSACTIONS_SAMPLE (CARDID, TRXN_DATE)
  local;
create unique index TRANSACTIONS_SAMPLEUI01 on TRANSACTIONS_SAMPLE (ID, PARTITIONKEY)
  local;
-- Create/Recreate primary, unique and foreign key constraints 
alter table TRANSACTIONS_SAMPLE
  add constraint TRANSACTIONS_SAMPLEPK primary key (ID, PARTITIONKEY);

--QUERY
Select * From (
Select t.AccountId From Transactions_sample t Group by t.Accountid Having Count(t.AccountId) > 10 order by dbms_random.random)
Where Rownum = 1

このクエリの問題は、テーブル全体のスキャンです。テーブルに完全にアクセスすることなく、同じ結果を達成したいと考えています。何か案は？

ありがとう