On 11.09.2019 1:03, Tomas Vondra wrote:
On Tue, Sep 10, 2019 at 04:30:41AM +0300, Nikita Glukhov wrote:
2. New AM method amattoptions().
amattoptions() is used to specify per-column AM-specific options.
The example is signature length for bloom indexes (patch #3).
I'm somewhat confused how am I supposed to use this, considering the patch
set only defines this for the contrib/bloom index AM. So let's say I want
to create a custom BRIN opclass with per-attribute options (like the two
BRIN opclasses I work on in the other thread). Clearly, I can't tweak the
IndexAmRoutine from the extension. ISTM the patch series should modify all
existing index AMs to have a valid amattoptions() implementation, calling
the new amproc if defined.
Or what is the correct way to define custom opclass for existing index AM
(e.g. BRIN) with attribute options?
Per-attribute opclass options are implemented independently from per-attribute
AM options. amattoptions() is optional and needs to be defined only if AM has
per-attribute options. amproc #0 is called regardless of whether amattoptions
is defined or not. That was the main reason why uniform procnum 0 was picked.
You should simply define function like that and use it as amproc #0:
Datum
brin_bloom_options(PG_FUNCTION_ARGS)
{ local_relopts *relopts = (local_relopts *) PG_GETARG_POINTER(0); BloomOptions *blopts = NULL;
extend_local_reloptions(relopts, blopts, sizeof(*blopts));
add_local_real_reloption(relopts, "n_distinct_per_range", "desc", -0.1, -1.0, INT_MAX, &blopts->nDistinctPerRange);
add_local_real_reloption(relopts, "false_positive_rate", "desc", 0.01, 0.001, 1.0, &blopts->falsePositiveRate);
PG_RETURN_VOID();
}