What is the fastest way to compare two values from different hashes? - ruby-on-rails

Question

I am trying to compare two hashes to see if the values match so i can reconcile some data.
I have a hash of existing accounts and a hash of accounts i need to check if they exist based on the existing accounts to see if it needs to be inserted.
# Reconcile Adaccounts
def self.reconcileAdaccounts(ad_accounts, user_id)
# These are the accounts that exist
existing_accounts = FbAdaccount.active
.select("fb_id")
.where("user_id = ?", user_id)
.as_json
ad_accounts.each do |ad_account|
if #here i would need to check if ad_account["account_id"] matches one of the existing records
p "This one already exists"
p ad_account["account_id"]
else
p "I need to create this one"
p ad_account["account_id"]
end
end
end
I could have nested loops but that does not seem like it would be the best solution, i also tried looking for any rails API functions that could do this but i have not found one.
What is the most efficient way of doing this?

Answer 1

What you're looking for is find_or_create_by. I've additionally wrapped the call in a transaction so all of this hits the database just once — in a single query.
def self.reconcileAdaccounts(ad_accounts, user_id)
FbAdaccount.transaction do
ad_accounts.each do |ad_account|
FbAdaccount.active
.select('fb_id')
.where('user_id = ?', user_id)
.find_or_create_by(ad_account['account_id'])
end
end
end
Transactions
A transaction doesn't magically alter the query, but it wraps it together so that it either all happens together, or doesn't happen at all.
With the following code:
numbers = (3..7).to_a
Ear.transaction do
numbers.each do |number|
Ear.find_or_create_by(bla: number)
end
end
Note the BEGIN and COMMIT statements. They signify where the call starts and ends.
(0.1ms) BEGIN
Ear Load (0.5ms) SELECT "ears".* FROM "ears" WHERE "ears"."bla" = $1 LIMIT $2 [["bla", 3], ["LIMIT", 1]]
Ear Create (0.8ms) INSERT INTO "ears" ("bla", "created_at", "updated_at") VALUES ($1, $2, $3) RETURNING "id" [["bla", 3], ["created_at", "2019-02-05 23:17:28.157989"], ["updated_at", "2019-02-05 23:17:28.157989"]]
Ear Load (0.2ms) SELECT "ears".* FROM "ears" WHERE "ears"."bla" = $1 LIMIT $2 [["bla", 4], ["LIMIT", 1]]
Ear Create (0.2ms) INSERT INTO "ears" ("bla", "created_at", "updated_at") VALUES ($1, $2, $3) RETURNING "id" [["bla", 4], ["created_at", "2019-02-05 23:17:28.160838"], ["updated_at", "2019-02-05 23:17:28.160838"]]
Ear Load (0.1ms) SELECT "ears".* FROM "ears" WHERE "ears"."bla" = $1 LIMIT $2 [["bla", 5], ["LIMIT", 1]]
Ear Create (0.2ms) INSERT INTO "ears" ("bla", "created_at", "updated_at") VALUES ($1, $2, $3) RETURNING "id" [["bla", 5], ["created_at", "2019-02-05 23:17:28.162241"], ["updated_at", "2019-02-05 23:17:28.162241"]]
Ear Load (0.2ms) SELECT "ears".* FROM "ears" WHERE "ears"."bla" = $1 LIMIT $2 [["bla", 6], ["LIMIT", 1]]
Ear Create (0.2ms) INSERT INTO "ears" ("bla", "created_at", "updated_at") VALUES ($1, $2, $3) RETURNING "id" [["bla", 6], ["created_at", "2019-02-05 23:17:28.163794"], ["updated_at", "2019-02-05 23:17:28.163794"]]
Ear Load (0.2ms) SELECT "ears".* FROM "ears" WHERE "ears"."bla" = $1 LIMIT $2 [["bla", 7], ["LIMIT", 1]]
Ear Create (0.2ms) INSERT INTO "ears" ("bla", "created_at", "updated_at") VALUES ($1, $2, $3) RETURNING "id" [["bla", 7], ["created_at", "2019-02-05 23:17:28.165589"], ["updated_at", "2019-02-05 23:17:28.165589"]]
(40.9ms) COMMIT
Now here's the same code, just without a transaction to wrap it in:
numbers = (20..25).to_a
numbers.each do |number|
Ear.find_or_create_by(bla: number)
end
Note the total number BEGIN and COMMIT messages:
Ear Load (249.3ms) SELECT "ears".* FROM "ears" WHERE "ears"."bla" = $1 LIMIT $2 [["bla", 20], ["LIMIT", 1]]
(73.4ms) BEGIN
Ear Create (48.7ms) INSERT INTO "ears" ("bla", "created_at", "updated_at") VALUES ($1, $2, $3) RETURNING "id" [["bla", 20], ["created_at", "2019-02-06 00:12:35.754374"], ["updated_at", "2019-02-06 00:12:35.754374"]]
(79.8ms) COMMIT
Ear Load (0.4ms) SELECT "ears".* FROM "ears" WHERE "ears"."bla" = $1 LIMIT $2 [["bla", 21], ["LIMIT", 1]]
(0.2ms) BEGIN
Ear Create (77.7ms) INSERT INTO "ears" ("bla", "created_at", "updated_at") VALUES ($1, $2, $3) RETURNING "id" [["bla", 21], ["created_at", "2019-02-06 00:12:35.918461"], ["updated_at", "2019-02-06 00:12:35.918461"]]
(0.3ms) COMMIT
Ear Load (0.2ms) SELECT "ears".* FROM "ears" WHERE "ears"."bla" = $1 LIMIT $2 [["bla", 22], ["LIMIT", 1]]
(0.2ms) BEGIN
Ear Create (2.7ms) INSERT INTO "ears" ("bla", "created_at", "updated_at") VALUES ($1, $2, $3) RETURNING "id" [["bla", 22], ["created_at", "2019-02-06 00:12:36.003822"], ["updated_at", "2019-02-06 00:12:36.003822"]]
(110.1ms) COMMIT
Ear Load (0.3ms) SELECT "ears".* FROM "ears" WHERE "ears"."bla" = $1 LIMIT $2 [["bla", 23], ["LIMIT", 1]]
(0.2ms) BEGIN
Ear Create (0.3ms) INSERT INTO "ears" ("bla", "created_at", "updated_at") VALUES ($1, $2, $3) RETURNING "id" [["bla", 23], ["created_at", "2019-02-06 00:12:36.125187"], ["updated_at", "2019-02-06 00:12:36.125187"]]
(37.0ms) COMMIT
Ear Load (0.2ms) SELECT "ears".* FROM "ears" WHERE "ears"."bla" = $1 LIMIT $2 [["bla", 24], ["LIMIT", 1]]
(0.2ms) BEGIN
Ear Create (0.4ms) INSERT INTO "ears" ("bla", "created_at", "updated_at") VALUES ($1, $2, $3) RETURNING "id" [["bla", 24], ["created_at", "2019-02-06 00:12:36.168414"], ["updated_at", "2019-02-06 00:12:36.168414"]]
(72.4ms) COMMIT
Ear Load (0.3ms) SELECT "ears".* FROM "ears" WHERE "ears"."bla" = $1 LIMIT $2 [["bla", 25], ["LIMIT", 1]]
(1.7ms) BEGIN
Ear Create (0.4ms) INSERT INTO "ears" ("bla", "created_at", "updated_at") VALUES ($1, $2, $3) RETURNING "id" [["bla", 25], ["created_at", "2019-02-06 00:12:36.249285"], ["updated_at", "2019-02-06 00:12:36.249285"]]
(121.2ms) COMMIT