Add support for Bulk Upserting records

Adds an `upsert` overload for Arrays to create large numbers of records at the same time.
Uses PG's UNNEST behavior to allow for a near-infinite (buyer beware) number of insertions
rather than being limited by PG's bind parameter restrictions (64k total binds, which would prevent
more than a few thousand upserts at a time depending on the number of column inserts).

Co-authored-by: Alex Piechowski <alex@piechowski.io>
Co-authored-by: robacarp <robacarp@users.noreply.github.com>

db/migrations/20220113043033_add_unique_constraint_to_users.cr

@@ -0,0 +1,9 @@
+class AddUniqueConstraintToUsers::V20220113043033 < Avram::Migrator::Migration::V1
+  def migrate
+    create_index :users, [:name, :nickname], unique: true
+  end
+
+  def rollback
+    drop_index :users, [:name, :nickname]
+  end
+end

spec/avram/operations/save_operation_spec.cr

@@ -66,6 +66,13 @@ private class ParamKeySaveOperation < ValueColumnModel::SaveOperation
 end
 
 private class UpsertUserOperation < User::SaveOperation
+  include QuerySpy
+
+  upsert_lookup_columns :name, :nickname
+  upsert_unique_on :name, :nickname
+end
+
+private class UpsertWithoutUniqueKeys < User::SaveOperation
   upsert_lookup_columns :name, :nickname
 end
 
@@ -307,6 +314,147 @@ describe "Avram::SaveOperation" do
     end
   end
 
+  describe ".upsert" do
+    it "should only proc one query" do
+      UpsertUserOperation.times_called = 0
+      some_time = Time.utc(2016, 2, 15, 10, 20, 30)
+
+      updates = [
+        {
+          name:       "Name 1",
+          nickname:   "Nickname 1",
+          age:        42,
+          joined_at:  some_time,
+          created_at: some_time,
+          updated_at: some_time,
+        },
+        {
+          name:       "Name 2",
+          nickname:   "Nickname 2",
+          age:        42,
+          joined_at:  some_time,
+          created_at: some_time,
+          updated_at: some_time,
+        },
+      ]
+
+      UpsertUserOperation.upsert(updates)
+      UpsertUserOperation.times_called.should eq 1
+    end
+
+    context "when a record already exists" do
+      before_each do
+        UserFactory.create do |u|
+          u.name("Name 1")
+          u.nickname("Nickname 1")
+          u.age(42)
+          u.year_born(1960)
+          u.joined_at(Time.utc)
+        end
+      end
+
+      it "allows manual passing of updated_at, but ignores created_at" do
+        some_time = Time.utc(2016, 2, 15, 10, 20, 30)
+
+        update = {
+          name:       "Name 1",
+          nickname:   "Nickname 1",
+          age:        42,
+          joined_at:  some_time,
+          created_at: some_time,
+          updated_at: some_time,
+        }
+
+        records = UpsertUserOperation.upsert([update])
+        records.first.created_at.should_not eq some_time
+        records.first.updated_at.should eq some_time
+      end
+
+      it "should create one, and update the other record" do
+        update = {
+          name:      "Name 1",
+          nickname:  "Nickname 1",
+          year_born: nil,
+          age:       42,
+          joined_at: Time.utc,
+        }
+
+        insert = {
+          name:      "Name 2",
+          nickname:  "Nickname 2",
+          year_born: 1980_i16,
+          age:       64,
+          joined_at: Time.utc,
+        }
+
+        records = UpsertUserOperation.upsert([update, insert])
+
+        records.first.id.should_not eq nil
+        records.last.id.should_not eq nil
+        records.first.year_born.should eq nil
+        records.last.year_born.should eq 1980_i16
+      end
+    end
+
+    context "when no records exist" do
+      it "allows manual passing of id" do
+        insert = {
+          id:        42_i64,
+          name:      "Name 1",
+          nickname:  "Nickname 1",
+          age:       42,
+          joined_at: Time.utc,
+        }
+
+        records = UpsertUserOperation.upsert([insert])
+        records.first.id.should eq 42_i64
+      end
+
+      it "allows manual passing of updated_at and created_at" do
+        some_time = Time.utc(2016, 2, 15, 10, 20, 30)
+
+        insert = {
+          name:       "Name 1",
+          nickname:   "Nickname 1",
+          age:        42,
+          joined_at:  some_time,
+          created_at: some_time,
+          updated_at: some_time,
+        }
+
+        records = UpsertUserOperation.upsert([insert])
+        records.first.id.should_not eq nil
+        records.first.created_at.should eq some_time
+        records.first.updated_at.should eq some_time
+      end
+    end
+
+    context "when the tuple values are passed in different orders" do
+      it "should upsert records" do
+        record_args = [
+          {
+            name:      "Name 1",
+            nickname:  "Nickname 1",
+            year_born: nil,
+            age:       42,
+            joined_at: Time.utc,
+          },
+          {
+            nickname:  "Nickname 2",
+            name:      "Name 2",
+            age:       42,
+            joined_at: Time.utc,
+            year_born: nil,
+          },
+        ]
+
+        records = UpsertUserOperation.upsert(record_args)
+        records.last.nickname.should eq "Nickname 2"
+        records.last.name.should eq "Name 2"
+      end
+    end
+  end
+
   describe "#errors" do
     it "includes errors for all operation attributes" do
       operation = SaveUser.new

spec/avram/view_spec.cr

@@ -12,9 +12,9 @@ describe "views" do
   end
 
   it "works without a primary key" do
-    UserFactory.new.nickname("Johnny").create
-    UserFactory.new.nickname("Johnny").create
-    UserFactory.new.nickname("Johnny").create
+    UserFactory.new.name("P1").nickname("Johnny").create
+    UserFactory.new.name("P2").nickname("Johnny").create
+    UserFactory.new.name("P3").nickname("Johnny").create
     nickname_info = NicknameInfo::BaseQuery.first
 
     nickname_info.nickname.should eq "Johnny"

src/avram/bulk_upsert.cr

@@ -0,0 +1,89 @@
+class Avram::BulkUpsert(T)
+  @column_types : Hash(String, String)
+  @permitted_fields : Array(Symbol)
+
+  def initialize(@records : Array(T),
+                 @conflicts : Array(Symbol),
+                 permitted_fields : Array(Symbol))
+    set_timestamps
+    @sample_record = @records.first.as(T)
+    @permitted_fields = permitted_fields_for(permitted_fields)
+
+    @column_types = T.database_table_info.columns.map do |col_info|
+      {
+        col_info.column_name,
+        col_info.data_type,
+      }
+    end.to_h
+  end
+
+  def statement
+    <<-SQL
+    INSERT INTO #{table}(#{fields})
+      (SELECT * FROM unnest(#{value_placeholders}))
+      ON CONFLICT (#{conflicts}) DO UPDATE SET #{updates}
+      RETURNING #{returning}
+    SQL
+  end
+
+  def args
+    @records.map do |record|
+      permitted_attributes(record).map(&.value)
+    end.transpose
+  end
+
+  private def permitted_fields_for(fields : Array(Symbol))
+    fields.push(:created_at) if @sample_record.responds_to?(:created_at)
+    fields.push(:updated_at) if @sample_record.responds_to?(:updated_at)
+    fields.uniq!
+  end
+
+  private def permitted_attributes(record)
+    record
+      .attributes
+      .select { |attr| @permitted_fields.includes?(attr.name) }
+  end
+
+  private def permitted_attributes
+    permitted_attributes(@sample_record)
+  end
+
+  private def conflicts
+    @conflicts.join(", ")
+  end
+
+  private def set_timestamps
+    @records.each do |record|
+      record.created_at.value ||= Time.utc if record.responds_to?(:created_at)
+      record.updated_at.value ||= Time.utc if record.responds_to?(:updated_at)
+    end
+  end
+
+  private def table
+    @sample_record.table_name
+  end
+
+  private def updates
+    (permitted_attribute_column_names - [:created_at]).compact_map do |column|
+      "#{column}=EXCLUDED.#{column}"
+    end.join(", ")
+  end
+
+  private def returning
+    T.column_names.join(", ")
+  end
+
+  private def permitted_attribute_column_names
+    permitted_attributes.map(&.name)
+  end
+
+  private def fields
+    permitted_attribute_column_names.map(&.to_s).join(", ")
+  end
+
+  private def value_placeholders
+    permitted_attributes.map_with_index(1) do |column, index|
+      "$#{index}::#{@column_types[column.name.to_s]}[]"
+    end.join(", ")
+  end
+end

src/avram/save_operation.cr

@@ -379,6 +379,14 @@ abstract class Avram::SaveOperation(T)
     @record.try &.id
   end
 
+  def self.column_names
+    T.column_names
+  end
+
+  def self.database_table_info
+    T.database_table_info.not_nil!
+  end
+
   def before_save; end
 
   def after_save(_record : T); end

src/avram/upsert.cr

@@ -90,6 +90,29 @@ module Avram::Upsert
     end
   end
 
+  macro upsert_unique_on(*attribute_names)
+    def self.upsert(upserts : Array(X)) forall X
+      \{%
+        if X > NamedTuple
+          raise("All array elements for #{@type}.upsert must be NamedTuples. You provided: #{X}")
+        elsif X.union?
+          keys = X.union_types.map(&.keys).join(", ")
+          raise("All tuples for #{@type}.upsert must have the same keys. Given: " + keys)
+        end
+      %}
+
+      upsert = Avram::BulkUpsert(self).new(
+        records: upserts.map { |upsert_args| new(**upsert_args) },
+        conflicts: {{ attribute_names }}.to_a,
+        permitted_fields: upserts.first.keys.to_a
+      )
+
+      new.database.query upsert.statement, args: upsert.args do |rs|
+        T.from_rs(rs)
+      end
+    end
+  end
+
   # :nodoc:
   macro included
     {% for method in ["upsert", "upsert!"] %}
@@ -100,5 +123,9 @@ module Avram::Upsert
         \{% raise "Please use the 'upsert_lookup_columns' macro in #{@type} before using '{{ method.id }}'" %}
       end
     {% end %}
+
+    def self.upsert(_upserts : Array)
+      \{% raise "Please use the 'upsert_unique_on' macro in #{@type} before using '.upsert'" %}
+    end
   end
 end

src/ext/db/param.cr

@@ -0,0 +1,8 @@
+# Can be removed once https://github.com/will/crystal-pg/pull/244 is merged.
+module PQ
+  record Param, slice : Slice(UInt8), size : Int32, format : Int16 do
+    def self.encode_array(io, value : Nil)
+      io << "NULL"
+    end
+  end
+end