Reclaiming space, and when you cannot

Deleting rows DOES NOT ALWAYS RETURN SPACE. What does, what it costs, and WHEN TO ACCEPT THE SIZE. This is the lesson that arrives after a successful purge, when somebody checks free space and finds nothing changed. DELETING ROWS FREES SPACE INSIDE THE TABLE RATHER THAN RETURNING IT TO THE TABLESPACE. The table keeps its allocated blocks and reuses them for new rows. So the purge worked, the table has room to grow into, and the tablespace is exactly as full as it was. THAT IS FINE FOR TABLES THAT WILL REFILL — WHICH IS MOST OF THEM. A request history table purged nightly will use that space again within days, and returning it to the tablespace only to allocate it back is work for no benefit. SO THE FIRST QUESTION IS WHETHER THE SPACE IS ACTUALLY NEEDED ELSEWHERE. If the tablespace has other tables that must grow, or the…

In this module: Module 12 · Space, growth and purging

1. 1What fills up, and in what order
2. 2Monitoring space before it matters
3. 3Growing a tablespace
4. 4The standard purge programs
5. 5Deciding what history to keep
6. 6Purging safely the first time
7. 7Reclaiming space, and when you cannot
8. 8What breaks: three space failures
9. 9Lab briefing · Fill it up on purpose