Most efficient way to query by nearest float value? - sql

Question

I have the following model:
class PlatformVersion(models.Model):
platform = models.ForeignKey(Platform)
version = models.FloatField(db_index=True)
display_version = models.CharField(max_length=32, db_index=True)
is_enabled = models.BooleanField(default=False)
Initial DB seeding code:
def add_version(self, platform, version, display_version):
try:
return PlatformVersion.objects.get(platform=platform, version=version)
except PlatformVersion.DoesNotExist:
return PlatformVersion.objects.create(platform=platform, version=version, display_version=display_version,
is_enabled=True)
self.add_version(platform, 9.0, '9.0')
self.add_version(platform, 9.1, '9.1')
self.add_version(platform, 9.2, '9.2')
self.add_version(platform, 9.3, '9.3')
As you can see, I'm adding minor versions only, skipping versions like 9.0.1, 9.0.2, etc.
And I have the following use-case: client sends request with platform version, that could be, for example, 9.0, 9.0.0 or 9.0.1 or 10.0 (missing in DB at all), etc. I need then to query the following PlatformVersion instance from DB:
for 9.0 -> 9.0
for 9.0.0 -> 9.0
for 9.0.1 -> 9.0
for 9.0.999 -> 9.0
for 9.1.1 -> 9.1
for 10.0 (10.* missing in DB) -> closest version = 9.3 for my initial seed data.
I'm sure I can write such code by myself, but there will be a really huge amount of such queries per second, so I care about efficiency.
Can you please suggest best option for performance?

Answer 1

Ok, I've realized that it's better to store major and minor versions as separate integer fields in my model, and filter by their values.
BTW, I think it's also a very bad practice to store versions like "x.x" in float field. If single field storage is required, it should be better to store version in DecimalField because of different float and decimal representaion.