active?()
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Is this connection alive and ready for queries?
def active?
@connection.query 'SELECT 1'
true
rescue PGError
false
end
adapter_name()
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Returns 'PostgreSQL' as adapter name for identification purposes.
def adapter_name
ADAPTER_NAME
end
add_column(table_name, column_name, type, options = {})
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Adds a new column to the named table. See TableDefinition#column for
details of the options you can use.
def add_column(table_name, column_name, type, options = {})
clear_cache!
add_column_sql = "ALTER TABLE #{quote_table_name(table_name)} ADD COLUMN #{quote_column_name(column_name)} #{type_to_sql(type, options[:limit], options[:precision], options[:scale])}"
add_column_options!(add_column_sql, options)
execute add_column_sql
end
begin_db_transaction()
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Begins a transaction.
def begin_db_transaction
execute "BEGIN"
end
change_column(table_name, column_name, type, options = {})
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Changes the column of a table.
def change_column(table_name, column_name, type, options = {})
clear_cache!
quoted_table_name = quote_table_name(table_name)
execute "ALTER TABLE #{quoted_table_name} ALTER COLUMN #{quote_column_name(column_name)} TYPE #{type_to_sql(type, options[:limit], options[:precision], options[:scale])}"
change_column_default(table_name, column_name, options[:default]) if options_include_default?(options)
change_column_null(table_name, column_name, options[:null], options[:default]) if options.key?(:null)
end
change_column_default(table_name, column_name, default)
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Changes the default value of a table column.
def change_column_default(table_name, column_name, default)
clear_cache!
execute "ALTER TABLE #{quote_table_name(table_name)} ALTER COLUMN #{quote_column_name(column_name)} SET DEFAULT #{quote(default)}"
end
change_column_null(table_name, column_name, null, default = nil)
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def change_column_null(table_name, column_name, null, default = nil)
clear_cache!
unless null || default.nil?
execute("UPDATE #{quote_table_name(table_name)} SET #{quote_column_name(column_name)}=#{quote(default)} WHERE #{quote_column_name(column_name)} IS NULL")
end
execute("ALTER TABLE #{quote_table_name(table_name)} ALTER #{quote_column_name(column_name)} #{null ? 'DROP' : 'SET'} NOT NULL")
end
clear_cache!()
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Clears the prepared statements cache.
def clear_cache!
@statements.clear
end
client_min_messages()
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Returns the current client message level.
def client_min_messages
query('SHOW client_min_messages', 'SCHEMA')[0][0]
end
client_min_messages=(level)
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Set the client message level.
def client_min_messages=(level)
execute("SET client_min_messages TO '#{level}'", 'SCHEMA')
end
columns(table_name, name = nil)
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Returns the list of all column definitions for a table.
def columns(table_name, name = nil)
column_definitions(table_name).collect do |column_name, type, default, notnull|
PostgreSQLColumn.new(column_name, default, type, notnull == 'f')
end
end
commit_db_transaction()
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Commits a transaction.
def commit_db_transaction
execute "COMMIT"
end
create_database(name, options = {})
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Create a new PostgreSQL database. Options include :owner,
:template, :encoding, :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'
def create_database(name, options = {})
options = options.reverse_merge(:encoding => "utf8")
option_string = options.symbolize_keys.sum do |key, value|
case key
when :owner
" OWNER = \"#{value}\""
when :template
" TEMPLATE = \"#{value}\""
when :encoding
" ENCODING = '#{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_savepoint()
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def create_savepoint
execute("SAVEPOINT #{current_savepoint_name}")
end
current_database()
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Returns the current database name.
def current_database
query('select current_database()')[0][0]
end
current_schema()
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Returns the current schema name.
def current_schema
query('SELECT current_schema', 'SCHEMA')[0][0]
end
disconnect!()
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Disconnects from the database if already connected. Otherwise, this method
does nothing.
def disconnect!
clear_cache!
@connection.close rescue nil
end
encoding()
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Returns the current database encoding format.
def encoding
query( SELECT pg_encoding_to_char(pg_database.encoding) FROM pg_database WHERE pg_database.datname LIKE '#{current_database}')[0][0]
end
escape_bytea(value)
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Escapes binary strings for bytea input to the database.
def escape_bytea(value)
@connection.escape_bytea(value) if value
end
exec_delete(sql, name = 'SQL', binds = [])
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def exec_delete(sql, name = 'SQL', binds = [])
log(sql, name, binds) do
result = binds.empty? ? exec_no_cache(sql, binds) :
exec_cache(sql, binds)
affected = result.cmd_tuples
result.clear
affected
end
end
exec_query(sql, name = 'SQL', binds = [])
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def exec_query(sql, name = 'SQL', binds = [])
log(sql, name, binds) do
result = binds.empty? ? exec_no_cache(sql, binds) :
exec_cache(sql, binds)
ret = ActiveRecord::Result.new(result.fields, result_as_array(result))
result.clear
return ret
end
end
exec_update(sql, name = 'SQL', binds = [])
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execute(sql, name = nil)
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Executes an SQL statement, returning a PGresult object on success or
raising a PGError exception otherwise.
def execute(sql, name = nil)
log(sql, name) do
@connection.async_exec(sql)
end
end
explain(arel, binds = [])
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DATABASE STATEMENTS ======================================
def explain(arel, binds = [])
sql = "EXPLAIN #{to_sql(arel, binds)}"
ExplainPrettyPrinter.new.pp(exec_query(sql, 'EXPLAIN', binds))
end
index_name_length()
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def index_name_length
63
end
indexes(table_name, name = nil)
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Returns an array of indexes for the given table.
def indexes(table_name, name = nil)
result = query( SELECT distinct i.relname, d.indisunique, d.indkey, pg_get_indexdef(d.indexrelid), t.oid FROM pg_class t INNER JOIN pg_index d ON t.oid = d.indrelid INNER JOIN pg_class i ON d.indexrelid = i.oid WHERE i.relkind = 'i' AND d.indisprimary = 'f' AND t.relname = '#{table_name}' AND i.relnamespace IN (SELECT oid FROM pg_namespace WHERE nspname = ANY (current_schemas(false)) ) ORDER BY i.relname, name)
result.map do |row|
index_name = row[0]
unique = row[1] == 't'
indkey = row[2].split(" ")
inddef = row[3]
oid = row[4]
columns = Hash[query( SELECT a.attnum, a.attname FROM pg_attribute a WHERE a.attrelid = #{oid} AND a.attnum IN (#{indkey.join(",")}), "Columns for index #{row[0]} on #{table_name}")]
column_names = columns.values_at(*indkey).compact
desc_order_columns = inddef.scan(/(\w+) DESC/).flatten
orders = desc_order_columns.any? ? Hash[desc_order_columns.map {|order_column| [order_column, :desc]}] : {}
column_names.empty? ? nil : IndexDefinition.new(table_name, index_name, unique, column_names, [], orders)
end.compact
end
insert_sql(sql, name = nil, pk = nil, id_value = nil, sequence_name = nil)
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Executes an INSERT query and returns the new record's ID
def insert_sql(sql, name = nil, pk = nil, id_value = nil, sequence_name = nil)
unless pk
table_ref = extract_table_ref_from_insert_sql(sql)
pk = primary_key(table_ref) if table_ref
end
if pk
select_value("#{sql} RETURNING #{quote_column_name(pk)}")
else
super
end
end
outside_transaction?()
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def outside_transaction?
@connection.transaction_status == PGconn::PQTRANS_IDLE
end
primary_key(table)
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Returns just a table's primary key
def primary_key(table)
row = exec_query( SELECT DISTINCT(attr.attname) FROM pg_attribute attr INNER JOIN pg_depend dep ON attr.attrelid = dep.refobjid AND attr.attnum = dep.refobjsubid INNER JOIN pg_constraint cons ON attr.attrelid = cons.conrelid AND attr.attnum = cons.conkey[1] WHERE cons.contype = 'p' AND dep.refobjid = $1::regclass, 'SCHEMA', [[nil, table]]).rows.first
row && row.first
end
quote_table_name(name)
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Checks the following cases:
def quote_table_name(name)
schema, name_part = extract_pg_identifier_from_name(name.to_s)
unless name_part
quote_column_name(schema)
else
table_name, name_part = extract_pg_identifier_from_name(name_part)
"#{quote_column_name(schema)}.#{quote_column_name(table_name)}"
end
end
reconnect!()
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Close then reopen the connection.
def reconnect!
clear_cache!
@connection.reset
configure_connection
end
release_savepoint()
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def release_savepoint
execute("RELEASE SAVEPOINT #{current_savepoint_name}")
end
rename_column(table_name, column_name, new_column_name)
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Renames a column in a table.
def rename_column(table_name, column_name, new_column_name)
clear_cache!
execute "ALTER TABLE #{quote_table_name(table_name)} RENAME COLUMN #{quote_column_name(column_name)} TO #{quote_column_name(new_column_name)}"
end
rename_index(table_name, old_name, new_name)
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def rename_index(table_name, old_name, new_name)
execute "ALTER INDEX #{quote_column_name(old_name)} RENAME TO #{quote_table_name(new_name)}"
end
rename_table(name, new_name)
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Renames a table. Also renames a table's primary key sequence if the
sequence name matches the Active Record default.
Example:
rename_table('octopuses', 'octopi')
def rename_table(name, new_name)
clear_cache!
execute "ALTER TABLE #{quote_table_name(name)} RENAME TO #{quote_table_name(new_name)}"
pk, seq = pk_and_sequence_for(new_name)
if seq == "#{name}_#{pk}_seq"
new_seq = "#{new_name}_#{pk}_seq"
execute "ALTER TABLE #{quote_table_name(seq)} RENAME TO #{quote_table_name(new_seq)}"
end
end
reset!()
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def reset!
clear_cache!
super
end
rollback_db_transaction()
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Aborts a transaction.
def rollback_db_transaction
execute "ROLLBACK"
end
rollback_to_savepoint()
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def rollback_to_savepoint
execute("ROLLBACK TO SAVEPOINT #{current_savepoint_name}")
end
schema_exists?(name)
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Returns true if schema exists.
def schema_exists?(name)
exec_query( SELECT COUNT(*) FROM pg_namespace WHERE nspname = $1, 'SCHEMA', [[nil, name]]).rows.first[0].to_i > 0
end
schema_search_path()
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Returns the active schema search path.
def schema_search_path
@schema_search_path ||= query('SHOW search_path', 'SCHEMA')[0][0]
end
schema_search_path=(schema_csv)
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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.
def schema_search_path=(schema_csv)
if schema_csv
execute("SET search_path TO #{schema_csv}", 'SCHEMA')
@schema_search_path = schema_csv
end
end
select_rows(sql, name = nil)
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Executes a SELECT query and returns an array of rows. Each row is an array
of field values.
def select_rows(sql, name = nil)
select_raw(sql, name).last
end
serial_sequence(table, column)
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def serial_sequence(table, column)
result = exec_query( SELECT pg_get_serial_sequence($1, $2), 'SCHEMA', [[nil, table], [nil, column]])
result.rows.first.first
end
session_auth=(user)
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Set the authorized user for this session
def session_auth=(user)
clear_cache!
exec_query "SET SESSION AUTHORIZATION #{user}"
end
sql_for_insert(sql, pk, id_value, sequence_name, binds)
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def sql_for_insert(sql, pk, id_value, sequence_name, binds)
unless pk
table_ref = extract_table_ref_from_insert_sql(sql)
pk = primary_key(table_ref) if table_ref
end
sql = "#{sql} RETURNING #{quote_column_name(pk)}" if pk
[sql, binds]
end
substitute_at(column, index)
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def substitute_at(column, index)
Arel::Nodes::BindParam.new "$#{index + 1}"
end
supports_ddl_transactions?()
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def supports_ddl_transactions?
true
end
supports_explain?()
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Returns true.
def supports_explain?
true
end
supports_index_sort_order?()
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def supports_index_sort_order?
true
end
supports_insert_with_returning?()
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def supports_insert_with_returning?
true
end
supports_migrations?()
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Returns true, since this connection adapter supports migrations.
def supports_migrations?
true
end
supports_savepoints?()
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Returns true, since this connection adapter supports savepoints.
def supports_savepoints?
true
end
supports_statement_cache?()
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Returns true, since this connection adapter supports prepared
statement caching.
def supports_statement_cache?
true
end
table_alias_length()
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Returns the configured supported identifier length supported by PostgreSQL
def table_alias_length
@table_alias_length ||= query('SHOW max_identifier_length')[0][0].to_i
end
table_exists?(name)
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Returns true if table exists. If the schema is not specified as part of
name then it will only find tables within the current schema
search path (regardless of permissions to access tables in other schemas)
def table_exists?(name)
schema, table = Utils.extract_schema_and_table(name.to_s)
return false unless table
binds = [[nil, table]]
binds << [nil, schema] if schema
exec_query( SELECT COUNT(*) FROM pg_class c LEFT JOIN pg_namespace n ON n.oid = c.relnamespace WHERE c.relkind in ('v','r') AND c.relname = $1 AND n.nspname = #{schema ? '$2' : 'ANY (current_schemas(false))'}, 'SCHEMA', binds).rows.first[0].to_i > 0
end
tables(name = nil)
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Returns the list of all tables in the schema search path or a specified
schema.
def tables(name = nil)
query( SELECT tablename FROM pg_tables WHERE schemaname = ANY (current_schemas(false)), 'SCHEMA').map { |row| row[0] }
end
type_cast(value, column)
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def type_cast(value, column)
return super unless column
case value
when String
return super unless 'bytea' == column.sql_type
{ :value => value, :format => 1 }
else
super
end
end
type_to_sql(type, limit = nil, precision = nil, scale = nil)
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Maps logical Rails types to PostgreSQL-specific data types.
def type_to_sql(type, limit = nil, precision = nil, scale = nil)
case type.to_s
when 'binary'
case limit
when nil, 0..0x3fffffff; super(type)
else raise(ActiveRecordError, "No binary type has byte size #{limit}.")
end
when 'integer'
return 'integer' unless limit
case limit
when 1, 2; 'smallint'
when 3, 4; 'integer'
when 5..8; 'bigint'
else raise(ActiveRecordError, "No integer type has byte size #{limit}. Use a numeric with precision 0 instead.")
end
else
super
end
end
unescape_bytea(value)
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Unescapes bytea output from a database to the binary string it represents.
NOTE: This is NOT an inverse of escape_bytea! This
is only to be used
on escaped binary output from database drive.
def unescape_bytea(value)
@connection.unescape_bytea(value) if value
end
update_sql(sql, name = nil)
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Executes an UPDATE query and returns the number of affected tuples.
def update_sql(sql, name = nil)
super.cmd_tuples
end