xtdb 2022-08-10 | Slack Archive

Ferdinand Beyer16:08:12

Stumbled over a strange behaviour the other day. Wonder if this is known before I try to create a minimal reproducing example. When using a map ::xt/id with metadata in a transaction including ::xt/match and ::xt/put ops, the transaction seems to be committed, but has no effect. Or maybe it does create a new document, not sure. Fetching the document by ::xt/id without metadata later on does not include any changes introduced by the ::xt/put. I stumbled across this by using select-keys to build my ::xt/id from some properties of my entity map. The entity map has metadata that was preserved by select-keys. Explicitly removing this metadata with (with-meta (select-keys entity keyseq) nil) does the trick for me.

richiardiandrea19:08:31

I don't think metadata is not serialized in xtdb and actually we ended up trimming/converting in application code cause we also ran into some kind of REPL problem

Ferdinand Beyer07:08:55

I created an issue for this, including a reproducing example: https://github.com/xtdb/xtdb/issues/1799

🙏 1

refset11:08:56

Thanks both - I just replied on the issue

Lucas Paszinski23:08:23

Hello, i’m new to clojure and xtdb, i want to order some players by player name, but want to return the whole entity.

(xt/q (xt/db node) '{:find [n (pull e [*])]
                     :where [[e :player/name n]
                             [e :xt/id id]]
                     :order-by [[n :asc]]}) 
;; => ["Breshad Perriman", {:player/name "Breshad Perriman", ... rest of keys/vals of entity

Lucas Paszinski23:08:02

Can i order without returning the name first, just the whole entity?

Lucas Paszinski23:08:18

i would expect this to work, but it does not (from what i read order-by works on the find)

(xt/q (xt/db node) '{:find [(pull e [*])]
                     :where [[e :player/name n]
                             [e :xt/id id]]
                     :order-by [[n :asc]]})

alexdavis23:08:05

I think you need to include the binding from order-by in the find, you can ignore it in the results though, (map first (xt/q node ‘{:find [(pull) n] :where …

➕ 1

Lucas Paszinski23:08:37

thx for the reply, thats what i ended up doing, but it felt weird, looks like i’m the right track than

Ferdinand Beyer07:08:56

One pattern I use a lot is this:

(->> (xt/q db '{:find [(pull e [*]) ...] :where ...})
     (map first))

E.g. I’m only interested in the first value of each result. Then you can easily append attributes you need for ordering, without changing the results. When your query produces one unique result, use ffirst to get the first value of the first tuple.

🙌 1

2022-08-10

Channels