Mike Walker (mike@xdbsystems.com)

Tracking the space used by your Informix instance over time is valuable to make sure that sufficient disk is provisioned for future growth.
This should be one of several metrics that the DBA should be recording at regular intervals.
But what if you don’t have that history? The sysmaster:sysfeatures table can provide the database size (total allocated and used), each week, for up to 5 years.
Use a query similar to the following to obtain this history:
select
year||"-"||to_char(week, "&&") period,
total_size,
total_size_used
from sysmaster:sysfeatures
order by year, week;

Example:

period           2025-07
total_size       10.6 TB
total_size_used  7.71 TB

period           2025-08
total_size       10.7 TB
total_size_used  7.73 TB

period           2025-09
total_size       10.7 TB
total_size_used  7.75 TB

period           2025-10
total_size       10.7 TB
total_size_used  7.75 TB

Loading this data into a spreadsheet gives the ability to plot how the Informix instance has changed in size.

We can use this same data to answer various questions such as, “how much space has been allocated over the last 12 months?”.
The sysmaster:sysfeatures table has multiple metrics and other information, all of which can be used to show how the instance has changed over time. Among other things, this includes the number of connections, the memory used, and the instance’s role in a cluster. The following is an example showing the most recent record in this table and the information that is recorded:
select first 1 *
from sysmaster:sysfeatures
order by year desc, week desc

week 38
year 2025
version 14.10.FC3
max_cpu_vps 15
max_vps 33
max_conns 298
max_sec_conns 0
max_sds_clones 0
max_rss_clones 0
total_size 10.9 TB
total_size_used 7.95 TB
max_memory 111 GB
max_memory_used 107 GB
is_primary 0
is_secondary 0
is_sds 0
is_rss 0
is_er 0
is_pdq 1