title: R - dbWriteTable Append not all data
body: <p>I'm using RmySQL to create and load data into tables on my local machine...</p>
  
  <p>first of all, after db connection, I create my table like that:</p>
  
  <pre><code>a&lt;-dbSendQuery(new.db, 'CREATE TABLE ALL_PLATFORMS_INFO(
                                      PLATFORM VARCHAR(15), 
                                      ID SMALLINT(5),
                                      PROBESET_ID VARCHAR(30),
                                      GENE_SYMBOL VARCHAR(20), 
                                      ENTREZ VARCHAR(15), 
                                      UNIGENE_ID VARCHAR(20), 
                                      GENE_TITLE VARCHAR(100), 
                                      DEPRECATED BOOLEAN,
                                      PRIMARY KEY (ID,PLATFORM)) 
                                      ENGINE=InnoDB;');
  </code></pre>
  
  <p>then I load a data frame with the same columns of database like that:</p>
  
  <pre><code>dbWriteTable(new.db, name='ALL_PLATFORMS_INFO', value=all.platforms.info.tab, row.names=F, append=T);
  </code></pre>
  
  <p>my structure all.platforms.info.tab has 67384 rows and 8 columns, but when I query my table on the database i obtain: 55050 rows...</p>
  
  <p>To avoid this I used the overvrite=T flag, but in this way I cannot declare primary keys...</p>
  
  <p>Why dbWriteTable behaves in this way?
  How can I declare primary keys using dbWriteTable?</p>
  
  <p>Thanks!</p>