--On Friday, July 21, 2023 3:32 PM +0000 Maud Parratt
<[email protected]> wrote:
why? to be clear I'm experimenting on a smaller ephemeral test instance
with non prod data, so there's no risk to trying things.
The man page spells it out pretty clearly:
index_hash64 { on | off }
Use a 64 bit hash for indexing. The default is to use 32
bit
hashes. These hashes are used for equality and
substring
indexing. The 64 bit version may be needed to avoid
index
collisions when the number of indexed values exceeds
~64
million. (Note that substring indexing generates multiple
index
values per actual attribute value.) Indices generated with
32
bit hashes are incompatible with the 64 bit version, and
vice
versa. Any existing databases must be fully reloaded
when
changing this setting. This directive is only supported on
64
bit CPUs.
I'm assuming that you have substring indices, and given the large size of
your database you may start having hash collissions.
You most likely also want to configure olcBkMdbIdlExp, sortvals, and
multival if you haven't.
--Quanah
