Problems with creating index

Question

I have over 1500MB free in tablespace
I use for indexes. When I attempt to create
index which should have about 300MB
it ends with error ORA-01652
unable to extend temp segment in tablespace
where my indexes reside.
Why Oracle needs so much space to create an index,
is there any way to do it without increasing
the size of tablespace?

Answer 1

Oracle needs no extra space in the tablespace beyond what is required to hold the index (INITIAL plus any additional extents allocated). My guess would be that you do not have a large enough contiginous chunk of free space to hold an additional extent.
If your tablespace is dictionary managed, look at the INITIAL, NEXT and PCTINCREASE parameters of your CREATE INDEX statement (or the tablespace defaults if you are not supplying them). Compare these to the sizes of the free space chunks in your index tablespace.
SELECT file_id, block_id, blocks, bytes
FROM dba_free_space
WHERE tablespace_name = 'YOUR_INDEX_TBS'
ORDER BY blocks DESCcompare the sizes of the first few rows here with the sizes of INITIAL and NEXT.
HTH
John