space alloc for detached indexes

Environment: HP K260 w/ HP-UX 10.20 Informix 7.31.UC2 1 gig RAM RAID 10 disc array How does Informix go about allocating space in detached index dbspaces? I am experimenting on my soon-to-be production machine. I built an index against a very large table in a dbscape just for that index, and when it was done an onstat -d shows zero free pages in the index chunk. The data pages for the table are only about 800 megs. I allocated 2 gigs in the chunk for this particular index, and all 2 gigs are being used? The index (which is unique) is composed of a 9 char column, a 2 char column, and a date column. Am I really out of space, or is space being pre-allocated by Informix? Any help appreciated. Allen Jantzen, DBA

allenj wrote: > > Environment: > HP K260 w/ HP-UX 10.20 > Informix 7.31.UC2 > 1 gig RAM > RAID 10 disc array > > How does Informix go about allocating space in detached index dbspaces? > > I am experimenting on my soon-to-be production machine. I built an > index against a very large table in a dbscape just for that index, and > when it was done an onstat -d shows zero free pages in the index chunk. > > The data pages for the table are only about 800 megs. I allocated 2 > gigs in the chunk for this particular index, and all 2 gigs are being > used? > > The index (which is unique) is composed of a 9 char column, a 2 char > column, and a date column. > > Am I really out of space, or is space being pre-allocated by Informix? Space for detached index extents is allocated like any other extents. If a new extent it needed it is allocated if not, not. There should be only one additional partly empty extent (unless masses of rows have been deleted). The sizing of the extents for a detached index is controlled by the EXTENT SIZE (for the first extent) and NEXT SIZE (for additional extents) attributes of the table you are indexing times the ratio of the index's keysize to rowsize. Note that if the table grew on its own that Informix will have doubled and redoubled the NEXT SIZE each time an additional 16 extents had been allocated so the NEXT SIZE for the table may be huge by now. Art S. Kagel