module ActiveRecord::ConnectionAdapters::PostgreSQL::SchemaStatements
Public Instance Methods
Source
# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 745 def add_exclusion_constraint(table_name, expression, **options) options = exclusion_constraint_options(table_name, expression, options) at = create_alter_table(table_name) at.add_exclusion_constraint(expression, options) execute schema_creation.accept(at) end
Adds a new exclusion constraint to the table. expression
is a String representation of a list of exclusion elements and operators.
add_exclusion_constraint :products, "price WITH =, availability_range WITH &&", using: :gist, name: "price_check"
generates:
ALTER TABLE "products" ADD CONSTRAINT price_check EXCLUDE USING gist (price WITH =, availability_range WITH &&)
The options
hash can include the following keys:
:name
-
The constraint name. Defaults to
excl_rails_<identifier>
. :deferrable
-
Specify whether or not the exclusion constraint should be deferrable. Valid values are
false
or:immediate
or:deferred
to specify the default behavior. Defaults tofalse
. :using
-
Specify which index method to use when creating this exclusion constraint (e.g.
:btree
,:gist
etc). :where
-
Specify an exclusion constraint on a subset of the table (internally PostgreSQL creates a partial index for this).
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 578 def add_foreign_key(from_table, to_table, **options) assert_valid_deferrable(options[:deferrable]) super end
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 796 def add_unique_constraint(table_name, column_name = nil, **options) options = unique_constraint_options(table_name, column_name, options) at = create_alter_table(table_name) at.add_unique_constraint(column_name, options) execute schema_creation.accept(at) end
Adds a new unique constraint to the table.
add_unique_constraint :sections, [:position], deferrable: :deferred, name: "unique_position", nulls_not_distinct: true
generates:
ALTER TABLE "sections" ADD CONSTRAINT unique_position UNIQUE (position) DEFERRABLE INITIALLY DEFERRED
If you want to change an existing unique index to deferrable, you can use :using_index to create deferrable unique constraints.
add_unique_constraint :sections, deferrable: :deferred, name: "unique_position", using_index: "index_sections_on_position"
The options
hash can include the following keys:
:name
-
The constraint name. Defaults to
uniq_rails_<identifier>
. :deferrable
-
Specify whether or not the unique constraint should be deferrable. Valid values are
false
or:immediate
or:deferred
to specify the default behavior. Defaults tofalse
. :using_index
-
To specify an existing unique index name. Defaults to
nil
. :nulls_not_distinct
-
Create a unique constraint where NULLs are treated equally. Note: only supported by PostgreSQL version 15.0.0 and greater.
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 291 def client_min_messages query_value("SHOW client_min_messages", "SCHEMA") end
Returns the current client message level.
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 296 def client_min_messages=(level) internal_execute("SET client_min_messages TO '#{level}'", "SCHEMA") end
Set the client message level.
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 235 def collation query_value("SELECT datcollate FROM pg_database WHERE datname = current_database()", "SCHEMA") end
Returns the current database collation.
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 22 def create_database(name, options = {}) options = { encoding: "utf8" }.merge!(options.symbolize_keys) option_string = options.each_with_object(+"") do |(key, value), memo| memo << case key when :owner " OWNER = \"#{value}\"" when :template " TEMPLATE = \"#{value}\"" when :encoding " ENCODING = '#{value}'" when :collation " LC_COLLATE = '#{value}'" when :ctype " LC_CTYPE = '#{value}'" when :tablespace " TABLESPACE = \"#{value}\"" when :connection_limit " CONNECTION LIMIT = #{value}" else "" end end execute "CREATE DATABASE #{quote_table_name(name)}#{option_string}" end
Create a new PostgreSQL database. Options include :owner
, :template
, :encoding
(defaults to utf8), :collation
, :ctype
, :tablespace
, and :connection_limit
(note that MySQL
uses :charset
while PostgreSQL uses :encoding
).
Example:
create_database config[:database], config create_database 'foo_development', encoding: 'unicode'
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 256 def create_schema(schema_name, force: nil, if_not_exists: nil) if force && if_not_exists raise ArgumentError, "Options `:force` and `:if_not_exists` cannot be used simultaneously." end if force drop_schema(schema_name, if_exists: true) end execute("CREATE SCHEMA#{' IF NOT EXISTS' if if_not_exists} #{quote_schema_name(schema_name)}") end
Creates a schema for the given schema name.
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 240 def ctype query_value("SELECT datctype FROM pg_database WHERE datname = current_database()", "SCHEMA") end
Returns the current database ctype.
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 220 def current_database query_value("SELECT current_database()", "SCHEMA") end
Returns the current database name.
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 225 def current_schema query_value("SELECT current_schema", "SCHEMA") end
Returns the current schema name.
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 269 def drop_schema(schema_name, **options) execute "DROP SCHEMA#{' IF EXISTS' if options[:if_exists]} #{quote_schema_name(schema_name)} CASCADE" end
Drops the schema for the given schema name.
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 230 def encoding query_value("SELECT pg_encoding_to_char(encoding) FROM pg_database WHERE datname = current_database()", "SCHEMA") end
Returns the current database encoding format.
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 663 def exclusion_constraints(table_name) scope = quoted_scope(table_name) exclusion_info = internal_exec_query(<<-SQL, "SCHEMA") SELECT conname, pg_get_constraintdef(c.oid) AS constraintdef, c.condeferrable, c.condeferred FROM pg_constraint c JOIN pg_class t ON c.conrelid = t.oid JOIN pg_namespace n ON n.oid = c.connamespace WHERE c.contype = 'x' AND t.relname = #{scope[:name]} AND n.nspname = #{scope[:schema]} SQL exclusion_info.map do |row| method_and_elements, predicate = row["constraintdef"].split(" WHERE ") method_and_elements_parts = method_and_elements.match(/EXCLUDE(?: USING (?<using>\S+))? \((?<expression>.+)\)/) predicate.remove!(/ DEFERRABLE(?: INITIALLY (?:IMMEDIATE|DEFERRED))?/) if predicate predicate = predicate.from(2).to(-3) if predicate # strip 2 opening and closing parentheses deferrable = extract_constraint_deferrable(row["condeferrable"], row["condeferred"]) options = { name: row["conname"], using: method_and_elements_parts["using"].to_sym, where: predicate, deferrable: deferrable } ExclusionConstraintDefinition.new(table_name, method_and_elements_parts["expression"], options) end end
Returns an array of exclusion constraints for the given table. The exclusion constraints are represented as ExclusionConstraintDefinition objects.
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 584 def foreign_keys(table_name) scope = quoted_scope(table_name) fk_info = internal_exec_query(<<~SQL, "SCHEMA", allow_retry: true, materialize_transactions: false) SELECT t2.oid::regclass::text AS to_table, a1.attname AS column, a2.attname AS primary_key, c.conname AS name, c.confupdtype AS on_update, c.confdeltype AS on_delete, c.convalidated AS valid, c.condeferrable AS deferrable, c.condeferred AS deferred, c.conkey, c.confkey, c.conrelid, c.confrelid FROM pg_constraint c JOIN pg_class t1 ON c.conrelid = t1.oid JOIN pg_class t2 ON c.confrelid = t2.oid JOIN pg_attribute a1 ON a1.attnum = c.conkey[1] AND a1.attrelid = t1.oid JOIN pg_attribute a2 ON a2.attnum = c.confkey[1] AND a2.attrelid = t2.oid JOIN pg_namespace t3 ON c.connamespace = t3.oid WHERE c.contype = 'f' AND t1.relname = #{scope[:name]} AND t3.nspname = #{scope[:schema]} ORDER BY c.conname SQL fk_info.map do |row| to_table = Utils.unquote_identifier(row["to_table"]) conkey = row["conkey"].scan(/\d+/).map(&:to_i) confkey = row["confkey"].scan(/\d+/).map(&:to_i) if conkey.size > 1 column = column_names_from_column_numbers(row["conrelid"], conkey) primary_key = column_names_from_column_numbers(row["confrelid"], confkey) else column = Utils.unquote_identifier(row["column"]) primary_key = row["primary_key"] end options = { column: column, name: row["name"], primary_key: primary_key } options[:on_delete] = extract_foreign_key_action(row["on_delete"]) options[:on_update] = extract_foreign_key_action(row["on_update"]) options[:deferrable] = extract_constraint_deferrable(row["deferrable"], row["deferred"]) options[:validate] = row["valid"] ForeignKeyDefinition.new(table_name, to_table, options) end end
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 633 def foreign_table_exists?(table_name) query_values(data_source_sql(table_name, type: "FOREIGN TABLE"), "SCHEMA").any? if table_name.present? end
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 629 def foreign_tables query_values(data_source_sql(type: "FOREIGN TABLE"), "SCHEMA") end
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 68 def index_name_exists?(table_name, index_name) table = quoted_scope(table_name) index = quoted_scope(index_name) query_value(<<~SQL, "SCHEMA").to_i > 0 SELECT COUNT(*) FROM pg_class t INNER JOIN pg_index d ON t.oid = d.indrelid INNER JOIN pg_class i ON d.indexrelid = i.oid LEFT JOIN pg_namespace n ON n.oid = t.relnamespace WHERE i.relkind IN ('i', 'I') AND i.relname = #{index[:name]} AND t.relname = #{table[:name]} AND n.nspname = #{table[:schema]} SQL end
Verifies existence of an index with a given name.
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 768 def remove_exclusion_constraint(table_name, expression = nil, **options) excl_name_to_delete = exclusion_constraint_for!(table_name, expression: expression, **options).name remove_constraint(table_name, excl_name_to_delete) end
Removes the given exclusion constraint from the table.
remove_exclusion_constraint :products, name: "price_check"
The expression
parameter will be ignored if present. It can be helpful to provide this in a migration’s change
method so it can be reverted. In that case, expression
will be used by add_exclusion_constraint
.
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 823 def remove_unique_constraint(table_name, column_name = nil, **options) unique_name_to_delete = unique_constraint_for!(table_name, column: column_name, **options).name remove_constraint(table_name, unique_name_to_delete) end
Removes the given unique constraint from the table.
remove_unique_constraint :sections, name: "unique_position"
The column_name
parameter will be ignored if present. It can be helpful to provide this in a migration’s change
method so it can be reverted. In that case, column_name
will be used by add_unique_constraint
.
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 566 def rename_index(table_name, old_name, new_name) validate_index_length!(table_name, new_name) schema, = extract_schema_qualified_name(table_name) execute "ALTER INDEX #{quote_table_name(schema) + '.' if schema}#{quote_column_name(old_name)} RENAME TO #{quote_table_name(new_name)}" end
Renames an index of a table. Raises error if length of new index name is greater than allowed limit.
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 434 def rename_table(table_name, new_name, **options) validate_table_length!(new_name) unless options[:_uses_legacy_table_name] clear_cache! schema_cache.clear_data_source_cache!(table_name.to_s) schema_cache.clear_data_source_cache!(new_name.to_s) execute "ALTER TABLE #{quote_table_name(table_name)} RENAME TO #{quote_table_name(new_name)}" pk, seq = pk_and_sequence_for(new_name) if pk # PostgreSQL automatically creates an index for PRIMARY KEY with name consisting of # truncated table name and "_pkey" suffix fitting into max_identifier_length number of characters. max_pkey_prefix = max_identifier_length - "_pkey".size idx = "#{table_name[0, max_pkey_prefix]}_pkey" new_idx = "#{new_name[0, max_pkey_prefix]}_pkey" execute "ALTER INDEX #{quote_table_name(idx)} RENAME TO #{quote_table_name(new_idx)}" # PostgreSQL automatically creates a sequence for PRIMARY KEY with name consisting of # truncated table name and "#{primary_key}_seq" suffix fitting into max_identifier_length number of characters. max_seq_prefix = max_identifier_length - "_#{pk}_seq".size if seq && seq.identifier == "#{table_name[0, max_seq_prefix]}_#{pk}_seq" new_seq = "#{new_name[0, max_seq_prefix]}_#{pk}_seq" execute "ALTER TABLE #{seq.quoted} RENAME TO #{quote_table_name(new_seq)}" end end rename_table_indexes(table_name, new_name, **options) end
Renames a table. Also renames a table’s primary key sequence if the sequence name exists and matches the Active Record default.
Example:
rename_table('octopuses', 'octopi')
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 63 def schema_exists?(name) query_value("SELECT COUNT(*) FROM pg_namespace WHERE nspname = #{quote(name)}", "SCHEMA").to_i > 0 end
Returns true if schema exists.
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 245 def schema_names query_values(<<~SQL, "SCHEMA") SELECT nspname FROM pg_namespace WHERE nspname !~ '^pg_.*' AND nspname NOT IN ('information_schema') ORDER by nspname; SQL end
Returns an array of schema names.
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 286 def schema_search_path @schema_search_path ||= query_value("SHOW search_path", "SCHEMA") end
Returns the active schema search path.
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 278 def schema_search_path=(schema_csv) if schema_csv internal_execute("SET search_path TO #{schema_csv}") @schema_search_path = schema_csv end end
Sets the schema search path to a string of comma-separated schema names. Names beginning with $ have to be quoted (e.g. $user => ‘$user’). See: www.postgresql.org/docs/current/static/ddl-schemas.html
This should be not be called manually but set in database.yml.
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 311 def serial_sequence(table, column) query_value("SELECT pg_get_serial_sequence(#{quote(table)}, #{quote(column)})", "SCHEMA") end
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 697 def unique_constraints(table_name) scope = quoted_scope(table_name) unique_info = internal_exec_query(<<~SQL, "SCHEMA", allow_retry: true, materialize_transactions: false) SELECT c.conname, c.conrelid, c.conkey, c.condeferrable, c.condeferred, pg_get_constraintdef(c.oid) AS constraintdef FROM pg_constraint c JOIN pg_class t ON c.conrelid = t.oid JOIN pg_namespace n ON n.oid = c.connamespace WHERE c.contype = 'u' AND t.relname = #{scope[:name]} AND n.nspname = #{scope[:schema]} SQL unique_info.map do |row| conkey = row["conkey"].delete("{}").split(",").map(&:to_i) columns = column_names_from_column_numbers(row["conrelid"], conkey) nulls_not_distinct = row["constraintdef"].start_with?("UNIQUE NULLS NOT DISTINCT") deferrable = extract_constraint_deferrable(row["condeferrable"], row["condeferred"]) options = { name: row["conname"], nulls_not_distinct: nulls_not_distinct, deferrable: deferrable } UniqueConstraintDefinition.new(table_name, columns, options) end end
Returns an array of unique constraints for the given table. The unique constraints are represented as UniqueConstraintDefinition objects.
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 926 def validate_check_constraint(table_name, **options) chk_name_to_validate = check_constraint_for!(table_name, **options).name validate_constraint table_name, chk_name_to_validate end
Validates the given check constraint.
validate_check_constraint :products, name: "price_check"
The options
hash accepts the same keys as add_check_constraint.
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 893 def validate_constraint(table_name, constraint_name) at = create_alter_table table_name at.validate_constraint constraint_name execute schema_creation.accept(at) end
Validates the given constraint.
Validates the constraint named constraint_name
on accounts
.
validate_constraint :accounts, :constraint_name
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 915 def validate_foreign_key(from_table, to_table = nil, **options) fk_name_to_validate = foreign_key_for!(from_table, to_table: to_table, **options).name validate_constraint from_table, fk_name_to_validate end
Validates the given foreign key.
Validates the foreign key on accounts.branch_id
.
validate_foreign_key :accounts, :branches
Validates the foreign key on accounts.owner_id
.
validate_foreign_key :accounts, column: :owner_id
Validates the foreign key named special_fk_name
on the accounts
table.
validate_foreign_key :accounts, name: :special_fk_name
The options
hash accepts the same keys as SchemaStatements#add_foreign_key
.
Private Instance Methods
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 1046 def add_column_for_alter(table_name, column_name, type, **options) return super unless options.key?(:comment) [super, Proc.new { change_column_comment(table_name, column_name, options[:comment]) }] end
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 1066 def add_index_opclass(quoted_columns, **options) opclasses = options_for_index_columns(options[:opclass]) quoted_columns.each do |name, column| column << " #{opclasses[name]}" if opclasses[name].present? end end
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 1073 def add_options_for_index_columns(quoted_columns, **options) quoted_columns = add_index_opclass(quoted_columns, **options) super end
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 1031 def assert_valid_deferrable(deferrable) return if !deferrable || %i(immediate deferred).include?(deferrable) raise ArgumentError, "deferrable must be `:immediate` or `:deferred`, got: `#{deferrable.inspect}`" end
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 1051 def change_column_for_alter(table_name, column_name, type, **options) change_col_def = build_change_column_definition(table_name, column_name, type, **options) sqls = [schema_creation.accept(change_col_def)] sqls << Proc.new { change_column_comment(table_name, column_name, options[:comment]) } if options.key?(:comment) sqls end
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 1058 def change_column_null_for_alter(table_name, column_name, null, default = nil) if default.nil? "ALTER COLUMN #{quote_column_name(column_name)} #{null ? 'DROP' : 'SET'} NOT NULL" else Proc.new { change_column_null(table_name, column_name, null, default) } end end
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 1152 def column_names_from_column_numbers(table_oid, column_numbers) Hash[query(<<~SQL, "SCHEMA")].values_at(*column_numbers).compact SELECT a.attnum, a.attname FROM pg_attribute a WHERE a.attrelid = #{table_oid} AND a.attnum IN (#{column_numbers.join(", ")}) SQL end
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 962 def create_alter_table(name) PostgreSQL::AlterTable.new create_table_definition(name) end
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 958 def create_table_definition(name, **options) PostgreSQL::TableDefinition.new(self, name, **options) end
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 1118 def data_source_sql(name = nil, type: nil) scope = quoted_scope(name, type: type) scope[:type] ||= "'r','v','m','p','f'" # (r)elation/table, (v)iew, (m)aterialized view, (p)artitioned table, (f)oreign table sql = +"SELECT c.relname FROM pg_class c LEFT JOIN pg_namespace n ON n.oid = c.relnamespace" sql << " WHERE n.nspname = #{scope[:schema]}" sql << " AND c.relname = #{scope[:name]}" if scope[:name] sql << " AND c.relkind IN (#{scope[:type]})" sql end
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 1088 def exclusion_constraint_for(table_name, **options) excl_name = exclusion_constraint_name(table_name, **options) exclusion_constraints(table_name).detect { |excl| excl.name == excl_name } end
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 1093 def exclusion_constraint_for!(table_name, expression: nil, **options) exclusion_constraint_for(table_name, expression: expression, **options) || raise(ArgumentError, "Table '#{table_name}' has no exclusion constraint for #{expression || options}") end
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 1078 def exclusion_constraint_name(table_name, **options) options.fetch(:name) do expression = options.fetch(:expression) identifier = "#{table_name}_#{expression}_excl" hashed_identifier = Digest::SHA256.hexdigest(identifier).first(10) "excl_rails_#{hashed_identifier}" end end
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 1037 def extract_constraint_deferrable(deferrable, deferred) deferrable && (deferred ? :deferred : :immediate) end
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 1023 def extract_foreign_key_action(specifier) case specifier when "c"; :cascade when "n"; :nullify when "r"; :restrict end end
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 1147 def extract_schema_qualified_name(string) name = Utils.extract_schema_qualified_name(string.to_s) [name.schema, name.identifier] end
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 995 def fetch_type_metadata(column_name, sql_type, oid, fmod) cast_type = get_oid_type(oid, fmod, column_name, sql_type) simple_type = SqlTypeMetadata.new( sql_type: sql_type, type: cast_type.type, limit: cast_type.limit, precision: cast_type.precision, scale: cast_type.scale, ) PostgreSQL::TypeMetadata.new(simple_type, oid: oid, fmod: fmod) end
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 966 def new_column_from_field(table_name, field, _definitions) column_name, type, default, notnull, oid, fmod, collation, comment, identity, attgenerated = field type_metadata = fetch_type_metadata(column_name, type, oid.to_i, fmod.to_i) default_value = extract_value_from_default(default) if attgenerated.present? default_function = default else default_function = extract_default_function(default_value, default) end if match = default_function&.match(/\Anextval\('"?(?<sequence_name>.+_(?<suffix>seq\d*))"?'::regclass\)\z/) serial = sequence_name_from_parts(table_name, column_name, match[:suffix]) == match[:sequence_name] end PostgreSQL::Column.new( column_name, default_value, type_metadata, !notnull, default_function, collation: collation, comment: comment.presence, serial: serial, identity: identity.presence, generated: attgenerated ) end
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 1129 def quoted_scope(name = nil, type: nil) schema, name = extract_schema_qualified_name(name) type = \ case type when "BASE TABLE" "'r','p'" when "VIEW" "'v','m'" when "FOREIGN TABLE" "'f'" end scope = {} scope[:schema] = schema ? quote(schema) : "ANY (current_schemas(false))" scope[:name] = quote(name) if name scope[:type] = type if type scope end
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 1041 def reference_name_for_table(table_name) _schema, table_name = extract_schema_qualified_name(table_name.to_s) table_name.singularize end
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 1007 def sequence_name_from_parts(table_name, column_name, suffix) over_length = [table_name, column_name, suffix].sum(&:length) + 2 - max_identifier_length if over_length > 0 column_name_length = [(max_identifier_length - suffix.length - 2) / 2, column_name.length].min over_length -= column_name.length - column_name_length column_name = column_name[0, column_name_length - [over_length, 0].min] end if over_length > 0 table_name = table_name[0, table_name.length - over_length] end "#{table_name}_#{column_name}_#{suffix}" end
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 1108 def unique_constraint_for(table_name, **options) name = unique_constraint_name(table_name, **options) unless options.key?(:column) unique_constraints(table_name).detect { |unique_constraint| unique_constraint.defined_for?(name: name, **options) } end
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 1113 def unique_constraint_for!(table_name, column: nil, **options) unique_constraint_for(table_name, column: column, **options) || raise(ArgumentError, "Table '#{table_name}' has no unique constraint for #{column || options}") end
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# File lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 1098 def unique_constraint_name(table_name, **options) options.fetch(:name) do column_or_index = Array(options[:column] || options[:using_index]).map(&:to_s) identifier = "#{table_name}_#{column_or_index * '_and_'}_unique" hashed_identifier = Digest::SHA256.hexdigest(identifier).first(10) "uniq_rails_#{hashed_identifier}" end end