clj-qldb

What?

clj-qldb is a small and lightweight library that allows you to use AWS QLDB without having to care about Java code, proprietary formats and all those distracting and boring things.

You send Clojure data and receive Clojure data, without wasting time.

Why?

From QLDB description:

Amazon QLDB is a fully managed ledger database that provides a transparent, immutable, and cryptographically verifiable transaction log ‎owned by a central trusted authority. Amazon QLDB tracks each and every application data change and maintains a complete and verifiable history of changes over time.

How?

Lein/Boot

[pbalduino/clj-qldb "0.1.1"]

deps.edn

pbalduino/clj-qldb {:mvn/version "0.1.1"}

Sample

;; The ledger name is a String. Here we're getting it from the environment.
;; For QLDB the ledger is like a database in the SQL world.
(def ledger-name (System/getenv "QLDB_LEDGER_NAME"))

;; Session is the gateway between this library and the service. You'll use it all the time.
(def session (create-session ledger-name))

;; Another string containing the table name. It's analog to a SQL table.
(def table-name "SAMPLE_TABLE")

(create-table session table-name)

;; Insert two rows:
(insert session table-name {:id "IUGBLMEAMHYGPNARTUOISSAZLYCTYDOL"
                            :name "Jeremias"
                            :age 42})

(insert session table-name {:id "TUPTVXWNBVJNOQLYFHOFWJWWEGKTTXTW"
                            :name "Humberto"
                            :age 20})

;; Query data:
(select session table-name :fields ["id" "name"])
; ({"id" "IUGBLMEAMHYGPNARTUOISSAZLYCTYDOL", "name" "Humberto"}
;  {"id" "TUPTVXWNBVJNOQLYFHOFWJWWEGKTTXTW", "name" "Jeremias"})

(select session table-name)
;({"id" "IUGBLMEAMHYGPNARTUOISSAZLYCTYDOL",
;  "name" "Humberto",
;  "age" 20}
; {"id" "TUPTVXWNBVJNOQLYFHOFWJWWEGKTTXTW",
;  "name" "Jeremias",
;  "age" 42})

(select session table-name :filter "age > 21")
; ({"id" "TUPTVXWNBVJNOQLYFHOFWJWWEGKTTXTW",
;   "name" "Jeremias",
;   "age" 42})

(select session table-name :filter "age < 21")
; ({"id" "IUGBLMEAMHYGPNARTUOISSAZLYCTYDOL",
;   "name" "Humberto",
;   "age" 20})

(select session table-name :fields ["count(*) as c"] :filter "age < 21")
; ({"c" 1})

(select session table-name :fields ["count(*) as c"])
; ({"c" 2})

;; Of course you don't need to create and drop tables all the time in the real world
(drop-table session table-name)

Who?

Plínio Balduino, software developer and problem solver.