add a tail_info struct to BlockStreamFix and make coresponding
modification.
BufferIterator is now supported!
complete the close method of Buffer Iterator
add buffer as a logical operator
fixed a bug caused by gethostbyname() in the exchange in exchangeLower.
gethostbyname() is replaced by other function call rather than making
gethostbyname() thread-safe.
A bug in Expander is fixed. Dec.30,2013
Remove the bucket initialization work in the construct method and bucket
is initialized in the first use.
Add TopN iterator;
fixed a bug in expander close();
Try to extend exchange. To be continue... Jan.3th
Exchanges with same exchangeID can be run at a single slave now! -Jun3
Complete_repartition hash join is now supported! --Jan.4th,2014
Fix a bug in MemoryStorage. --Jan.6th, 2014
upload .cproject from Li's DELL.
Optimizing the query response time by removing the usage of Receiver()
in Theron::Actor
Try to optimize the query respose time. To be continued....
objects now are serialized into binary archive.
ProjectionScan now has an additional parameter sample_rate_ which
spefics block-level sampling.
Merge pull request #5 from wangli1426/developing

Developing
getOptimalPhysicalPlan has been implemeted for Scan and Root logical
Operator. --JAN.14, 2014 by Li Wang
fixed bug in the getOptimalPhysicalPlan in Scan and root