#include <userver/storages/postgres/component.hpp>
PosgreSQL client component.
Provides access to a PostgreSQL cluster.
You must specify either dbalias or dbconnection. If the component is configured with an alias, it will lookup connection data in Secdist.
It is a common practice to provide a database connection string via environment variables. To retrieve a value from the environment use dbconnection#env: THE_ENV_VARIABLE_WITH_CONNECTION_STRING as described in yaml_config::YamlConfig.
You must specify blocking_task_processor as well.
max_replication_lag can be used to tune replication lag limit for replicas. Once the replica lag exceeds this value it will be automatically disabled. Note, however, that client-size lag detection is not precise in nature and can only provide the precision of couple seconds.
A PosgreSQL alias in secdist is described as a JSON array of objects containing a single cluster description. There are two formats of describing a cluster, the first one assigns predefined roles to DSNs, the second one is just a list of DSNs and the Postgres component takes care of discovering the cluster's topology itself.
In predefined roles format the component requires single-host connection strings.
The predefined roles format is deprecated and the support will be removed soon.
In automatic discovery format the connection strings are any valid PostgreSQL connection strings including multi-host ones with the exception of target_session_attrs which will be ignored.
The shard_number parameter is required in both formats and must match the index of cluster description object in the alias array.
Please see PostgreSQL documentation on connection strings.
| Name | Description | Default value |
|---|---|---|
| dbalias | name of the database in secdist config (if available) | – |
| dbconnection | connection DSN string (used if no dbalias specified) | – |
| blocking_task_processor | name of task processor for background blocking operations | – |
| max_replication_lag | replication lag limit for usable slaves | 60s |
| sync-start | perform initial connections synchronously | false |
| dns_resolver | server hostname resolver type (getaddrinfo or async) | 'async' |
| persistent-prepared-statements | cache prepared statements or not | true |
| user-types-enabled | allow use of user-defined types | true |
| check-user-types | cancel service start if some user types have not been loaded, which helps to detect missing migrations | false |
| ignore_unused_query_params | disable check for not-NULL query params that are not used in query | false |
| monitoring-dbalias | name of the database for monitorings | calculated from dbalias or dbconnection options |
| max_prepared_cache_size | prepared statements cache size limit | 200 |
| max_statement_metrics | limit of exported metrics for named statements | 0 |
| min_pool_size | number of connections created initially | 4 |
| max_pool_size | maximum number of created connections for "connlimit_mode: manual" | 15 |
| max_queue_size | maximum number of clients waiting for a connection | 200 |
| connecting_limit | limit for concurrent establishing connections number per pool (0 - unlimited) | 0 |
| connlimit_mode | max_connections setup mode (manual or auto), also see uPg: Automatic connection limit | auto |
| error-injection | artificial error injection settings, error_injection::Settings | – |
Definition at line 141 of file component.hpp.
Inheritance diagram for components::Postgres:Public Member Functions | |
| Postgres (const ComponentConfig &, const ComponentContext &) | |
| Component constructor. | |
| ~Postgres () override | |
| Component destructor. | |
| storages::postgres::ClusterPtr | GetCluster () const |
| Cluster accessor for default shard number. | |
| storages::postgres::ClusterPtr | GetClusterForShard (size_t shard) const |
| Cluster accessor for specific shard number. | |
| size_t | GetShardCount () const |
| Get total shard count. | |
| storages::postgres::DatabasePtr | GetDatabase () const |
| Get database object. | |
| void | ExtendStatistics (utils::statistics::Writer &writer) |
| Reports statistics for PostgreSQL driver. | |
| ComponentHealth | GetComponentHealth () const override |
| void | OnLoadingCancelled () override |
| void | OnAllComponentsLoaded () override |
| void | OnAllComponentsAreStopping () override |
Static Public Member Functions | |
| static yaml_config::Schema | GetStaticConfigSchema () |
Static Public Attributes | |
| static constexpr size_t | kDefaultShardNumber = 0 |
| Default shard number. | |
| static constexpr storages::postgres::CommandControl | kDefaultCommandControl |
| Default command control. | |
Protected Types | |
| using | LoggableComponentBase = ComponentBase |
| Legacy alias, use ComponentBase instead. | |
|
protectedinherited |
Legacy alias, use ComponentBase instead.
Definition at line 69 of file component_base.hpp.
|
inlineoverridevirtualinherited |
Override this function to inform the world of the state of your component.
Reimplemented from components::RawComponentBase.
Definition at line 35 of file component_base.hpp.
|
inline |
Get database object.
Definition at line 166 of file component.hpp.
|
inlineoverridevirtualinherited |
Component may use this function to stop doing work before the stop of the components that depend on it.
Base components may override it and make final to do some work before the derived object constructor is called. Don't use it otherwise.
Reimplemented from components::RawComponentBase.
Reimplemented in urabbitmq::ConsumerComponentBase, and components::Server.
Definition at line 60 of file component_base.hpp.
|
inlineoverridevirtualinherited |
Component may use this function to finalize registration of other components that depend on it (for example, handler components register in server component, and the latter uses OnAllComponentsLoaded() to start processing requests).
Base components may override it and make final to do some work after the derived object constructor is called. Don't use it otherwise.
Reimplemented from components::RawComponentBase.
Reimplemented in urabbitmq::ConsumerComponentBase, components::Server, and server::handlers::Ping.
Definition at line 53 of file component_base.hpp.
|
inlineoverridevirtualinherited |
Called once if the creation of any other component failed. If the current component expects some other component to take any action with the current component, this call is a signal that such action may never happen due to components loading was cancelled. Application components might not want to override it.
Reimplemented from components::RawComponentBase.
Definition at line 44 of file component_base.hpp.
|
staticconstexpr |
Default command control.
Definition at line 146 of file component.hpp.
|
staticconstexpr |
Default shard number.
Definition at line 144 of file component.hpp.
