a question on about DBLINK

DB1: Oracle Database 11g Enterprise Edition Release 11.2.0.3.0
DB2: Oracle Database 11g Enterprise Edition Release 11.2.0.3.0
there is a table named PROD_INST that has one hundred million rows on DB1:
-- Create table
create table PROD_INST
(
PROD_INST_ID NUMBER(12) not null,
PRODUCT_ID NUMBER(12),
ACC_PROD_INST_ID NUMBER(12),
ADDRESS_ID NUMBER(12),
OWNER_CUST_ID NUMBER(12),
PAYMENT_MODE_CD VARCHAR2(6),
PRODUCT_PASSWORD VARCHAR2(30)
)
tablespace TBS_DATA_GC
pctfree 10
initrans 1
maxtrans 255
storage
(
initial 64K
minextents 1
maxextents unlimited
);
-- Create/Recreate indexes
create UNIQUE index PK_PROD_INST on PROD_INST (PROD_INST_ID)
tablespace TBS_DATA_GC
pctfree 10
initrans 2
maxtrans 255