title: Is creating a large volume table without a primary key problematic - Oracle 11g?
body: <p>In Oracle 11g I was thinking of creating a table that looks like this:</p>
  
  <pre><code>CREATE TABLE SOME_TABLE (
    MACHINE_ID      NUMBER(10,0) NOT NULL ENABLE,
    CYCLE_ID        NUMBER NOT NULL ENABLE,
    START_TIME      TIMESTAMP (6) NOT NULL ENABLE,
    DATA            VARCHAR2(255),
    CONSTRAINT "PK_SOME_TABLE" PRIMARY KEY ("MACHINE_ID", "CYCLE_ID")
  )
  </code></pre>
  
  <p>This table will receive approximately 2.5 million records per day.</p>
  
  <p>The CYCLE_ID is taken from a sequence, and is part of the primary key.</p>
  
  <p>I am worried that using a sequence for the CYCLE_ID for this amount of data is a bad idea because the sequence will restart at 0 at some point in time, thus resulting in duplicate key errors.</p>
  
  <p>Would it be better to remove the CYCLE_ID from the table, thus leaving the table without a unique key ? What problems can I expect from having such a large volume table without a unique primary key ?</p>
  
  <p>Thank you very much.</p>