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#datomic
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2019-07-17
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sooheon08:07:38

What, if any, are the differences between missing? and not in the following?

sooheon08:07:09

(d/q '[:find (pull ?feed [*])
       :where
       [?feed :rss-feed/url]
       [(missing? $ ?feed :rss-feed/etag)]]
     db)

(d/q '[:find (pull ?feed [*])
       :where
       [?feed :rss-feed/url]
       (not [?feed :rss-feed/etag])]
     db)

sooheon08:07:28

The only thing I’ve noticed is that missing? doesn’t complain when you ask for a never-transacted attribute (i.e. (missing? $ ?e :random-made-up-or-misspelled-kw))

dmarjenburgh09:07:04

Can you configure the path to ion-config.edn? I have slightly different configurations per environment.

holger10:07:28

is it possible that two jvm processes share the same valcache (directory) for a short period of time? our deployment first starts a new version before it stops the old one

jaret18:07:34

Yes, I believe valcache directory can be shared, but it has not been tested. Not to put you out on a limb, but if you notice any issues could you send them to me in support? And I encourage you to test in non-production first.

jaret18:07:39

I’d also be interested to see metrics from your test system. Given that we haven’t tested this configuration it remains unsupported, but theoretically could work.

holger15:07:59

Thanks! In case we decide to go that route, I'll let you know!