Space Requirements for Text Index

Creating a text index requires storage space. The CISCTX_INDEX_SPACE tablespace is created when you install Oracle Text Search using EDM. The CISCTX_INDEX_SPACE tablespace size of 200 MB, 1000 MB, 3000 MB, and 5000 MB is allocated for tiny, small, medium, and large databases.
 

Note: In theory, the size of a Text Index could be 30 to 100 percent of original text size. When you have large amount of text to index, you might want to consider adding more space to tablespaces CISCTX_INDEX_SPACE and UNDO before you proceed with the index creation.
 

When creating a Text Index, these eleven objects are created internally in CISCTX_INDEX_SPACE:
 

DR$<index_name>$I

SYS_IL<number>$$

SYS_LOB<number>$$

DR$<index_name>$K

SYS_IOT_TOP_<number>

DR$<index_name>$R

SYS_IL<number>$$

SYS_LOB<number>$$

DR$<index_name>$N

SYS_IOT_TOP_<number>

DR$<index_name>$X

The minimum space allocation for these objects is approximately 14 MB for every Text Index you create. The maximum allocation depends on the number of rows and the length of data on the indexed column in your table.