#include <userver/storages/postgres/options.hpp>

Detailed Description

A structure to control timeouts for PosrgreSQL queries

There are two parameters, execute and statement.

execute parameter controls the overall time the driver spends executing a query, that includes:

connecting to PostgreSQL server, if there are no connections available and connection pool still has space for new connections;
waiting for a connection to become idle if there are no idle connections and connection pool already has reached it's max size;
preparing a statement if the statement is run for the first time on the connection;
binding parameters and executing the statement;
waiting for the first results to arrive from the server. If the result set is big, only time to the first data packet is taken into account.

statement is rather straightforward, it's the PostgreSQL server-side parameter, and it controls the time the database backend can spend executing a single statement. It is very costly to change the statement timeout often, as it requires a roundtrip to the database to change the setting.

See also: https://www.postgresql.org/docs/12/runtime-config-client.html

execute timeout should always be greater than the statement timeout! If the statement timeout happens to be greater than (or too close to) the execute timeout, the driver caps the effective statement timeout to be below the execute timeout (by a small margin when the execute timeout is large enough to spare it), so that the database gets a chance to cancel the statement on its own before the driver gives up waiting on the network.

In case of a timeout, either back-end or overall, the client gets an exception and the driver tries to clean up the connection for further reuse.

Examples: postgresql/functional_tests/basic_chaos/postgres_service.cpp.

Definition at line 122 of file options.hpp.

Public Types
enum class	PreparedStatementsOptionOverride { kNoOverride , kEnabled , kDisabled }

Public Member Functions
constexpr	CommandControl (TimeoutDuration network_timeout_ms, TimeoutDuration statement_timeout_ms, PreparedStatementsOptionOverride prepared_statements_enabled=PreparedStatementsOptionOverride::kNoOverride)
constexpr CommandControl	WithExecuteTimeout (TimeoutDuration n) const noexcept
constexpr CommandControl	WithStatementTimeout (TimeoutDuration s) const noexcept
bool	operator== (const CommandControl &rhs) const

Public Attributes
TimeoutDuration	network_timeout_ms {}
	Overall timeout for a command being executed.
TimeoutDuration	statement_timeout_ms {}
	PostgreSQL server-side timeout.
PreparedStatementsOptionOverride	prepared_statements_enabled {PreparedStatementsOptionOverride::kNoOverride}

Member Enumeration Documentation

◆ PreparedStatementsOptionOverride

enum class storages::postgres::CommandControl::PreparedStatementsOptionOverride

strong

Definition at line 128 of file options.hpp.

Constructor & Destructor Documentation

◆ CommandControl()

storages::postgres::CommandControl::CommandControl	(	TimeoutDuration	network_timeout_ms,
		TimeoutDuration	statement_timeout_ms,
		PreparedStatementsOptionOverride	prepared_statements_enabled = PreparedStatementsOptionOverride::kNoOverride )

inlineconstexpr

Definition at line 132 of file options.hpp.

Member Function Documentation

◆ operator==()

bool storages::postgres::CommandControl::operator== ( const CommandControl & rhs ) const

inline

Definition at line 146 of file options.hpp.

◆ WithExecuteTimeout()

CommandControl storages::postgres::CommandControl::WithExecuteTimeout ( TimeoutDuration n ) const

inlineconstexprnoexcept

Definition at line 142 of file options.hpp.

◆ WithStatementTimeout()

CommandControl storages::postgres::CommandControl::WithStatementTimeout ( TimeoutDuration s ) const

inlineconstexprnoexcept

Definition at line 144 of file options.hpp.

Member Data Documentation

◆ network_timeout_ms

TimeoutDuration storages::postgres::CommandControl::network_timeout_ms {}

Overall timeout for a command being executed.

Definition at line 124 of file options.hpp.

◆ prepared_statements_enabled

PreparedStatementsOptionOverride storages::postgres::CommandControl::prepared_statements_enabled {PreparedStatementsOptionOverride::kNoOverride}

Definition at line 130 of file options.hpp.

◆ statement_timeout_ms

TimeoutDuration storages::postgres::CommandControl::statement_timeout_ms {}

PostgreSQL server-side timeout.

Definition at line 126 of file options.hpp.

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

userver/storages/postgres/options.hpp