commit_prepared_transaction(transaction_id)
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Commit an existing prepared transaction with the given transaction
identifier string.
def commit_prepared_transaction(transaction_id)
run("COMMIT PREPARED #{literal(transaction_id)}")
end
create_function(name, definition, opts={})
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Creates the function in the database. Arguments:
-
name : name of the function to create
-
definition : string definition of the function, or object file for a
dynamically loaded C function.
-
opts : options hash:
-
:args : function arguments, can be either a symbol or string specifying a
type or an array of 1-3 elements:
-
element 1 : argument data type
-
element 2 : argument name
-
element 3 : argument mode (e.g. in, out, inout)
-
:behavior : Should be IMMUTABLE, STABLE, or VOLATILE. PostgreSQL assumes
VOLATILE by default.
-
:cost : The estimated cost of the function, used by the query planner.
-
:language : The language the function uses. SQL
is the default.
-
:link_symbol : For a dynamically loaded see function, the function's link
symbol if different from the definition argument.
-
:returns : The data type returned by the function. If you are using OUT or
INOUT argument modes, this is ignored. Otherwise, if this is not specified,
void is used by default to specify the function is not supposed to return a
value.
-
:rows : The estimated number of rows the function will return. Only use if
the function returns SETOF something.
-
:security_definer : Makes the privileges of the function the same as the
privileges of the user who defined the function instead of the privileges
of the user who runs the function. There are security implications when
doing this, see the PostgreSQL documentation.
-
:set : Configuration variables to set while the function is being run, can
be a hash or an array of two pairs. search_path is often used here if
:security_definer is used.
-
:strict : Makes the function return NULL when any argument is NULL.
def create_function(name, definition, opts={})
self << create_function_sql(name, definition, opts)
end
create_language(name, opts={})
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Create the procedural language in the database. Arguments:
def create_language(name, opts={})
self << create_language_sql(name, opts)
end
create_trigger(table, name, function, opts={})
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Create a trigger in the database. Arguments:
-
table : the table on which this trigger operates
-
name : the name of this trigger
-
function : the function to call for this trigger, which should return type
trigger.
-
opts : options hash:
-
:after : Calls the trigger after execution instead of before.
-
:args : An argument or array of arguments to pass to the function.
-
:each_row : Calls the trigger for each row instead of for each statement.
-
:events : Can be :insert, :update, :delete, or an array of any of those.
Calls the trigger whenever that type of statement is used. By default, the
trigger is called for insert, update, or delete.
def create_trigger(table, name, function, opts={})
self << create_trigger_sql(table, name, function, opts)
end
database_type()
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PostgreSQL uses the :postgres database type.
def database_type
:postgres
end
drop_function(name, opts={})
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Drops the function from the database. Arguments:
def drop_function(name, opts={})
self << drop_function_sql(name, opts)
end
drop_language(name, opts={})
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Drops a procedural language from the database. Arguments:
def drop_language(name, opts={})
self << drop_language_sql(name, opts)
end
drop_trigger(table, name, opts={})
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Drops a trigger from the database. Arguments:
def drop_trigger(table, name, opts={})
self << drop_trigger_sql(table, name, opts)
end
indexes(table, opts={})
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Use the pg_* system tables to determine indexes on a table
def indexes(table, opts={})
m = output_identifier_meth
im = input_identifier_meth
schema, table = schema_and_table(table)
range = 0...32
attnums = server_version >= 80100 ? SQL::Function.new(:ANY, :ind__indkey) : range.map{|x| SQL::Subscript.new(:ind__indkey, [x])}
ds = metadata_dataset.
from(:pg_class___tab).
join(:pg_index___ind, :indrelid=>:oid, im.call(table)=>:relname).
join(:pg_class___indc, :oid=>:indexrelid).
join(:pg_attribute___att, :attrelid=>:tab__oid, :attnum=>attnums).
filter(:indc__relkind=>'i', :ind__indisprimary=>false, :indexprs=>nil, :indpred=>nil).
order(:indc__relname, range.map{|x| [SQL::Subscript.new(:ind__indkey, [x]), x]}.case(32, :att__attnum)).
select(:indc__relname___name, :ind__indisunique___unique, :att__attname___column)
ds.join!(:pg_namespace___nsp, :oid=>:tab__relnamespace, :nspname=>schema.to_s) if schema
ds.filter!(:indisvalid=>true) if server_version >= 80200
ds.filter!(:indisready=>true, :indcheckxmin=>false) if server_version >= 80300
indexes = {}
ds.each do |r|
i = indexes[m.call(r[:name])] ||= {:columns=>[], :unique=>r[:unique]}
i[:columns] << m.call(r[:column])
end
indexes
end
locks()
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Dataset containing all current database locks
def locks
dataset.from(:pg_class).join(:pg_locks, :relation=>:relfilenode).select(:pg_class__relname, Sequel::SQL::ColumnAll.new(:pg_locks))
end
notify(channel, opts={})
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Notifies the given channel. See the PostgreSQL NOTIFY documentation.
Options:
:payload |
The payload string to use for the NOTIFY statement. Only supported in
PostgreSQL 9.0+.
|
:server |
The server to which to send the NOTIFY statement, if the sharding support
is being used.
|
def notify(channel, opts={})
execute_ddl("NOTIFY #{channel}#{", #{literal(opts[:payload].to_s)}" if opts[:payload]}", opts)
end
primary_key(table, opts={})
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Return primary key for the given table.
def primary_key(table, opts={})
quoted_table = quote_schema_table(table)
return @primary_keys[quoted_table] if @primary_keys.include?(quoted_table)
@primary_keys[quoted_table] = if conn = opts[:conn]
conn.primary_key(*schema_and_table(table))
else
synchronize(opts[:server]){|con| con.primary_key(*schema_and_table(table))}
end
end
primary_key_sequence(table, opts={})
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Return the sequence providing the default for the primary key for the given
table.
def primary_key_sequence(table, opts={})
quoted_table = quote_schema_table(table)
return @primary_key_sequences[quoted_table] if @primary_key_sequences.include?(quoted_table)
@primary_key_sequences[quoted_table] = if conn = opts[:conn]
conn.sequence(*schema_and_table(table))
else
synchronize(opts[:server]){|con| con.sequence(*schema_and_table(table))}
end
end
reset_primary_key_sequence(table)
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Reset the primary key sequence for the given table, baseing it on the
maximum current value of the table's primary key.
def reset_primary_key_sequence(table)
pk = SQL::Identifier.new(primary_key(table))
return unless seq = primary_key_sequence(table)
db = self
seq_ds = db.from(seq.lit)
get{setval(seq, db[table].select{coalesce(max(pk)+seq_ds.select{:increment_by}, seq_ds.select(:min_value))}, false)}
end
rollback_prepared_transaction(transaction_id)
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Rollback an existing prepared transaction
with the given transaction identifier string.
def rollback_prepared_transaction(transaction_id)
run("ROLLBACK PREPARED #{literal(transaction_id)}")
end
serial_primary_key_options()
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PostgreSQL uses SERIAL psuedo-type instead of AUTOINCREMENT for managing
incrementing primary keys.
def serial_primary_key_options
{:primary_key => true, :serial => true, :type=>Integer}
end
server_version(server=nil)
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The version of the PostgreSQL server, used for determining capability.
def server_version(server=nil)
return @server_version if @server_version
@server_version = synchronize(server) do |conn|
(conn.server_version rescue nil) if conn.respond_to?(:server_version)
end
unless @server_version
@server_version = if m = /PostgreSQL (\d+)\.(\d+)(?:(?:rc\d+)|\.(\d+))?/.match(fetch('SELECT version()').single_value)
(m[1].to_i * 10000) + (m[2].to_i * 100) + m[3].to_i
else
0
end
end
@server_version
end
supports_create_table_if_not_exists?()
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PostgreSQL supports CREATE TABLE IF NOT EXISTS on 9.1+
def supports_create_table_if_not_exists?
server_version >= 90100
end
supports_prepared_transactions?()
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PostgreSQL supports prepared transactions (two-phase commit) if
max_prepared_transactions is greater than 0.
def supports_prepared_transactions?
return @supports_prepared_transactions if defined?(@supports_prepared_transactions)
@supports_prepared_transactions = self['SHOW max_prepared_transactions'].get.to_i > 0
end
supports_savepoints?()
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PostgreSQL supports savepoints
def supports_savepoints?
true
end
supports_transaction_isolation_levels?()
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PostgreSQL supports transaction isolation levels
def supports_transaction_isolation_levels?
true
end
tables(opts={}, &block)
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Array of symbols specifying table names in
the current database. The dataset used is yielded to the block if one is
provided, otherwise, an array of symbols of table names is returned.
Options:
def tables(opts={}, &block)
pg_class_relname('r', opts, &block)
end
views(opts={})
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Array of symbols specifying view names in
the current database.
Options:
def views(opts={})
pg_class_relname('v', opts)
end