elasticsearch/docs/reference/migration/migrate_8_0/indices.asciidoc

[float]
[[breaking_80_indices_changes]]
=== Indices changes

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==== Force Merge API changes

Previously, the Force Merge API allowed the parameters `only_expunge_deletes`
and `max_num_segments` to be set to a non default value at the same time. But
the `max_num_segments` was silently ignored when `only_expunge_deletes` is set
to `true`, leaving the false impression that it has been applied.

The Force Merge API now rejects requests that have a `max_num_segments` greater
than or equal to 0 when the `only_expunge_deletes` is set to true.

[float]
==== On-disk term dictionary cannot be disabled

The `index.force_memory_term_dictionary` setting was introduced in 7.0 as a
temporary measure to allow users to opt-out of the optimization that leaves the
term dictionary on disk when appropriate. This optimization is now mandatory
and the setting is removed.