Who does Coalescing?

Answer is given here. Drag your mouse and read. SMON coalesces the free space. SMON stands for SYSTEM MONITOR. Coalescing means : If two or more neighbouring extents are free, they will be merged together and made as a single large free extent. SMON will not do coalescing if the pctincrease is set to zero for a tablespace. I am having a tablespace with name SALES. I want to coalesce this tablespace by giving a command. What is the command? SQL> ALTER TABLESPACE SALES COALESCE; But what is the use of manual coalescing when smon is there? If you think that smon's periodical coalescing is an overhead, you can make the pctincrease of the concerned tablespace to 0. If pctincrease=0,then smon will not do coalescing. You can manually coalesce using the command: alter tablespace cloaesce;