Add option to create indexes concurrently. Fixes #1124 (#1127)

Author: jwoertink

spec/avram/migrator/create_index_statement_spec.cr

@@ -7,6 +7,9 @@ describe Avram::Migrator::CreateIndexStatement do
 
     statement = Avram::Migrator::CreateIndexStatement.new(:users, columns: :email, using: :btree, unique: true).build
     statement.should eq %(CREATE UNIQUE INDEX users_email_index ON users USING btree ("email");)
+
+    statement = Avram::Migrator::CreateIndexStatement.new(:users, columns: :email, using: :btree, concurrently: true).build
+    statement.should eq %(CREATE INDEX CONCURRENTLY users_email_index ON users USING btree ("email");)
   end
 
   it "supports other index types" do

spec/avram/migrator/migration_spec.cr

@@ -88,6 +88,16 @@ class MigrationCreateAndDropSequences::V994 < Avram::Migrator::Migration::V1
   end
 end
 
+class MigrationCreateAndDropIndexes::V993 < Avram::Migrator::Migration::V1
+  def migrate
+    create_index(:accounts, [:user_id, :number], unique: true, concurrently: true, name: "idx_account_user_id_number")
+  end
+
+  def rollback
+    drop_index(:accounts, [:user_id, :number], if_exists: true)
+  end
+end
+
 describe Avram::Migrator::Migration::V1 do
   it "executes statements in a transaction" do
     expect_raises Avram::FailedMigration do
@@ -136,6 +146,18 @@ describe Avram::Migrator::Migration::V1 do
       sql.should contain "DROP TRIGGER IF EXISTS trigger_touch_updated_at"
       sql.should contain "CREATE TRIGGER trigger_touch_updated_at"
     end
+
+    it "generates proper SQL for indexes" do
+      migration = MigrationCreateAndDropIndexes::V993.new
+      migration.migrate
+      sql = migration.prepared_statements.join("\n")
+
+      sql.should contain %(CREATE UNIQUE INDEX CONCURRENTLY idx_account_user_id_number ON accounts USING btree ("user_id", "number"))
+
+      migration.rollback
+      sql = migration.prepared_statements.join("\n")
+      sql.should contain %(DROP INDEX IF EXISTS accounts_user_id_number_index)
+    end
   end
 
   describe "if _not_ exists" do

src/avram/migrator/create_index_statement.cr

@@ -36,7 +36,7 @@ class Avram::Migrator::CreateIndexStatement
     Brin
   end
 
-  def initialize(@table : TableName, @columns : Columns, using : Symbol = :btree, @unique = false, @name : String? | Symbol? = nil)
+  def initialize(@table : TableName, @columns : Columns, using : Symbol = :btree, @unique : Bool = false, @concurrently : Bool = false, @name : String? | Symbol? = nil)
     @using = IndexTypes.parse?(using.to_s)
     raise "index type '#{using}' not supported" if @using.nil?
   end
@@ -49,7 +49,9 @@ class Avram::Migrator::CreateIndexStatement
     String.build do |index|
       index << "CREATE"
       index << " UNIQUE" if @unique
-      index << " INDEX " << index_name
+      index << " INDEX "
+      index << "CONCURRENTLY " if @concurrently
+      index << index_name
       index << " ON " << @table
       index << " USING " << @using.to_s.downcase
       index << " (" << mapped_columns << ");"

src/avram/migrator/statement_helpers.cr

@@ -36,8 +36,8 @@ module Avram::Migrator::StatementHelpers
     prepared_statements << DropForeignKeyStatement.new(from, references, column).build
   end
 
-  def create_index(table_name : TableName, columns : Columns, unique = false, using = :btree, name : String? | Symbol? = nil)
-    prepared_statements << CreateIndexStatement.new(table_name, columns, using, unique, name).build
+  def create_index(table_name : TableName, columns : Columns, unique = false, concurrently = false, using = :btree, name : String? | Symbol? = nil)
+    prepared_statements << CreateIndexStatement.new(table_name, columns, using, unique, concurrently, name).build
   end
 
   def drop_index(table_name : TableName, columns : Columns? = nil, if_exists = false, on_delete = :do_nothing, name : String? | Symbol? = nil)