pqxx::robusttransaction< ISOLATION > Class Template Reference

Slightly slower, better-fortified version of transaction. More...

#include <robusttransaction.hxx>

Inheritance diagram for pqxx::robusttransaction< ISOLATION >:

Public Member Functions
	robusttransaction (connection &c, std::string_view tname)
	robusttransaction (connection &c, std::string &&tname)
	robusttransaction (connection &c)
virtual	~robusttransaction () noexcept override
Public Member Functions inherited from pqxx::internal::basic_robusttransaction
virtual	~basic_robusttransaction () override=0
Public Member Functions inherited from pqxx::transaction_base
	transaction_base ()=delete
	transaction_base (transaction_base const &)=delete
	transaction_base (transaction_base &&)=delete
transaction_base &	operator= (transaction_base const &)=delete
transaction_base &	operator= (transaction_base &&)=delete
virtual	~transaction_base ()=0
void	commit ()
	Commit the transaction. More...
void	abort ()
	Abort the transaction. More...
connection &	conn () const
	The connection in which this transaction lives. More...
void	set_variable (std::string_view var, std::string_view value)
	Set session variable using SQL "SET" command. More...
std::string	get_variable (std::string_view)
	Read session variable using SQL "SHOW" command. More...
std::string_view	name () const noexcept
	Transaction name, if you passed one to the constructor; or empty string. More...
template<>
zview	query_value (zview query, std::string_view desc)=delete
	Forbidden specialisation: underlying buffer immediately goes out of scope. More...
std::string	esc (char const text[]) const
	Escape string for use as SQL string literal in this transaction. More...
std::string	esc (char const text[], std::size_t maxlen) const
	Escape string for use as SQL string literal in this transaction. More...
std::string	esc (std::string_view text) const
	Escape string for use as SQL string literal in this transaction. More...
std::string	esc_raw (unsigned char const data[], std::size_t len) const
	Escape binary data for use as SQL string literal in this transaction. More...
std::string	esc_raw (zview) const
	Escape binary data for use as SQL string literal in this transaction. More...
std::string	unesc_raw (zview text) const
	Unescape binary data, e.g. from a table field or notification payload. More...
std::string	unesc_raw (char const *text) const
	Unescape binary data, e.g. from a table field or notification payload. More...
template<typename T >
std::string	quote (T const &t) const
	Represent object as SQL string, including quoting & escaping. More...
std::string	quote_raw (unsigned char const bin[], std::size_t len) const
	Binary-escape and quote a binary string for use as an SQL constant. More...
std::string	quote_raw (zview bin) const
	Binary-escape and quote a binary string for use as an SQL constant. More...
std::string	quote_name (std::string_view identifier) const
	Escape an SQL identifier for use in a query. More...
std::string	esc_like (std::string_view bin, char escape_char='\\') const
	Escape string for literal LIKE match. More...
result	exec (std::string_view query, std::string_view desc=std::string_view{})
	Execute a command. More...
result	exec (std::stringstream const &query, std::string_view desc=std::string_view{})
	Execute a command. More...
result	exec0 (zview query, std::string_view desc=std::string_view{})
	Execute command, which should return zero rows of data. More...
row	exec1 (zview query, std::string_view desc=std::string_view{})
	Execute command returning a single row of data. More...
result	exec_n (result::size_type rows, zview query, std::string_view desc=std::string_view{})
	Execute command, expect given number of rows. More...
template<typename TYPE >
TYPE	query_value (zview query, std::string_view desc=std::string_view{})
	Perform query, expecting exactly 1 row with 1 field, and convert it. More...
template<typename... TYPE>
auto	stream (std::string_view query)
	Execute a query, and loop over the results row by row. More...
template<typename... Args>
result	exec_params (zview query, Args &&...args)
	Execute an SQL statement with parameters. More...
template<typename... Args>
row	exec_params1 (zview query, Args &&...args)
template<typename... Args>
result	exec_params0 (zview query, Args &&...args)
template<typename... Args>
result	exec_params_n (std::size_t rows, zview query, Args &&...args)
template<typename... Args>
result	exec_prepared (zview statement, Args &&...args)
	Execute a prepared statement, with optional arguments. More...
template<typename... Args>
row	exec_prepared1 (zview statement, Args &&...args)
	Execute a prepared statement, and expect a single-row result. More...
template<typename... Args>
result	exec_prepared0 (zview statement, Args &&...args)
	Execute a prepared statement, and expect a result with zero rows. More...
template<typename... Args>
result	exec_prepared_n (result::size_type rows, zview statement, Args &&...args)
	Execute a prepared statement, expect a result with given number of rows. More...
void	process_notice (char const msg[]) const
	Have connection process a warning message. More...
void	process_notice (zview msg) const
	Have connection process a warning message. More...

Additional Inherited Members
Protected Member Functions inherited from pqxx::internal::basic_robusttransaction
	basic_robusttransaction (connection &c, zview begin_command, std::string_view tname)
	basic_robusttransaction (connection &c, zview begin_command)
Protected Member Functions inherited from pqxx::dbtransaction
	dbtransaction (connection &c)
	Begin transaction. More...
	dbtransaction (connection &c, std::string_view tname)
	Begin transaction. More...
	dbtransaction (connection &c, std::string_view tname, std::shared_ptr< std::string > rollback_cmd)
	Begin transaction. More...
Protected Member Functions inherited from pqxx::transaction_base
	transaction_base (connection &c, std::string_view tname, std::shared_ptr< std::string > rollback_cmd)
	Create a transaction (to be called by implementation classes only). More...
	transaction_base (connection &c, std::string_view tname)
	Create a transaction (to be called by implementation classes only). More...
	transaction_base (connection &c)
	Create a transaction (to be called by implementation classes only). More...
void	register_transaction ()
	Register this transaction with the connection. More...
void	close () noexcept
	End transaction. To be called by implementing class' destructor. More...
virtual void	do_abort ()
	Transaction type-specific way of aborting a transaction. More...
void	set_rollback_cmd (std::shared_ptr< std::string > cmd)
	Set the rollback command. More...
result	direct_exec (std::string_view, std::string_view desc=""sv)
	Execute query on connection directly. More...
result	direct_exec (std::shared_ptr< std::string >, std::string_view desc=""sv)

Detailed Description

template<isolation_level ISOLATION = read_committed>
class pqxx::robusttransaction< ISOLATION >

Slightly slower, better-fortified version of transaction.

Requires PostgreSQL 10 or better.

robusttransaction is similar to transaction, but spends more time and effort to deal with the hopefully rare case that the connection to the backend is lost just while it's trying to commit. In such cases, the client does not know whether the backend (on the other side of the broken connection) managed to commit the transaction.

When this happens, robusttransaction tries to reconnect to the database and figure out what happened.

This service level was made optional since you may not want to pay the overhead where it is not necessary. Certainly the use of this class makes no sense for local connections, or for transactions that read the database but never modify it, or for noncritical database manipulations.

Besides being slower, it's also more complex. Which means that in practice a robusttransaction could actually fail more instead of less often than a normal transaction. What robusttransaction tries to achieve is to give you certainty, not just be more successful per se.

Constructor & Destructor Documentation

robusttransaction() [1/3]

template<isolation_level ISOLATION = read_committed>

pqxx::robusttransaction< ISOLATION >::robusttransaction	(	connection &	c,
		std::string_view	tname
	)

Create robusttransaction of given name.

Parameters

c	Connection inside which this robusttransaction should live.
name	optional human-readable name for this transaction.

robusttransaction() [2/3]

template<isolation_level ISOLATION = read_committed>

pqxx::robusttransaction< ISOLATION >::robusttransaction	(	connection &	c,
		std::string &&	tname
	)

Create robusttransaction of given name.

Parameters

c	Connection inside which this robusttransaction should live.
name	optional human-readable name for this transaction.

robusttransaction() [3/3]

template<isolation_level ISOLATION = read_committed>

pqxx::robusttransaction< ISOLATION >::robusttransaction ( connection &  c )

explicit

Create robusttransaction of given name.

Parameters

c	Connection inside which this robusttransaction should live.
name	optional human-readable name for this transaction.

~robusttransaction()

template<isolation_level ISOLATION = read_committed>

virtual pqxx::robusttransaction< ISOLATION >::~robusttransaction ( )

overridevirtualnoexcept

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The documentation for this class was generated from the following file:

• robusttransaction.hxx