PCTFREE

In Jonathan Lewis' cbo Buch findet man auf Seite 64 eine schöne Zusammenfassung der Wirkung der PCTFREE-Angabe für Tabellen und Indizes. Dort heisst es:

For indexes, pctfree is only relevant as an index is created, rebuild, or coalesced; and it only applies to leaf blocks.

For a table, the pctfree storage parameter tells Oracle when to stop inserting new rows into a block, so that some space in each block can be left for updates to existing rows in that block. But entries in indexes are never updated - when you change an index entry it (usually) belongs somewhere else in the index, thus an update to an index is really a delete followed by an insert - so you don't reserve space for updates, you reserve space for new rows.

Neu für mich war die Einschränkung auf Leaf-Blocks für den Fall der Indizes - oder zumindest hatte ich sie vergessen.