Coalescing

True statement regarding space management is:
In a locally managed tablespace free space are managed by bitmap
Coalescing of free space is not required in a locally managed tablespace
n.b.: Coalescing free space is not necessary for locally managed tablespaces, because bitmaps automatically track adjacent free space.
But free space in a dictionary managed tablespace can become fragmented, making it difficult to allocate new extents. For this way coalescing of free space is needed in a dictionary managed tablespace.
SQL > ALTER TABLESPACE tabsp_4 COALESCE;
Coalescing operation reduces one of the index partitions, which are partitioned using hash method. This method redistributes the index entries of an indexed partition.
SQL > ALTER INDEX parts1_hgidx COALESCE PARTITION PARALLEL