Hi Vinoth,
Accelerator file is used to accelerate the repository loading process,when the repository is loaded immediately,the data representation and indices are read from accelerator file if it exists.when the repository is loaded with update indices, it rebuild index files and index the data stored in DB,the result is flushed in the accelerator file.so as for your problem,you can shut down your MDM Server,delete all the accelerator files and then start MDM Server, load all the repositories with update indices.
hope it helps you.
best regards
Stephen