feat: srw #1586
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feat: srw #1586
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sergiyvamz
reviewed
Nov 4, 2025
| | Plugin codes / Plugin codes | [limitless](./using-plugins/UsingTheLimitlessConnectionPlugin.md) | [bg](./using-plugins/UsingTheBlueGreenPlugin.md) | | ||
| |--------------------------------------------------|-------------------------------------------------------------------|--------------------------------------------------| | ||
| | [bg](./using-plugins/UsingTheBlueGreenPlugin.md) | <span style="color:red;font-size:20px">✗</span> | | | ||
| | Plugin codes / Plugin codes | [limitless](./using-plugins/UsingTheLimitlessConnectionPlugin.md) | [bg](./using-plugins/UsingTheBlueGreenPlugin.md) | |
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srw is not compatible with readWriteSplitting plugin.
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and not with auroraStaleDns
sergiyvamz
reviewed
Nov 4, 2025
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| ## Loading the Simple Read/Write Splitting Plugin | ||
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| The simple read/write splitting plugin is not loaded by default. To load the plugin, include it in the `wrapperPlugins` connection parameter. If you would like to load the simple read/write splitting plugin alongside the failover and host monitoring plugins, the simple read/write splitting plugin must be listed before these plugins in the plugin chain. If it is not, failover exceptions will not be properly processed by the plugin. See the example below to properly load the read/write splitting plugin with these plugins. |
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the simple read/write splitting plugin must be listed before these plugins in the plugin chain
That's a bit outdated statement. The driver sort plugins automatically so plugin order isn't so important. However, if user opt out with auto sorting then certainly srw should go before failover and efm.
sergiyvamz
reviewed
Nov 4, 2025
| properties.setProperty("srwReadEndpoint", "test-db.cluster-ro-XYZ.us-east-2.rds.amazonaws.com"); | ||
| ``` | ||
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| ## Federated Authentication Plugin Parameters |
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Federated? Should it be SRW Plugin Parameters?
sergiyvamz
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Nov 4, 2025
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| The property `verifyNewSrwConnections` is enabled by default. This means that when new connections are made with the simple read/write splitting plugin, a query is sent to the new connection to verify its role. If a write connection connects to a reader, an error is thrown. If a read connection connects to the writer, a warning is logged and the connection is not stored for reuse. | ||
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| #### Non-Aurora clusters |
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Non-Aurora and non RDS Cluster?
sergiyvamz
reviewed
Nov 4, 2025
| The verification step uses an Aurora specific query to determine the role of the connection, if the endpoint is not to an Aurora database, disable `verifyNewSrwConnections` by setting it to `false` in the properties. | ||
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| #### Autocommit | ||
| If `verifyNewSrwConnections` is enabled and autocommit is set to false when the simple read/write splitting plugin makes a new connection, unexpected errors such as `Cannot change transaction read-only property in the middle of a transaction.` will occur. As part of verification, the plugin executes a query against a new connection, which when autocommit is set to false will open a transaction. |
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Can we rephrase it? It's hard to understand when the occurs and what to do to fix it.
sergiyvamz
reviewed
Nov 4, 2025
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| ## Supplying the connection string | ||
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| When using the simple read/write splitting plugin against Aurora clusters, you do not have to supply multiple instance URLs in the connection string. Instead, supply just the URL for the initial instance to which you're connecting. You must also include either the failover plugin or the Aurora host list plugin in your plugin chain so that the driver knows to query Aurora for its topology. See the section on [loading the simple read/write splitting plugin](#loading-the-simple-readwrite-splitting-plugin) for more info. |
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Aurora and RDS clusters?
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What is Aurora host list plugin ?
sergiyvamz
reviewed
Nov 4, 2025
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| To take full advantage of the benefits of RDS Proxy it is recommended to only connect through RDS Proxy endpoints. See [Using the AWS JDBC Driver with RDS Proxy](./../../../README.md#rds-proxy) for limitations. | ||
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| ## Using the Simple Read/Write Splitting Plugin against non-Aurora clusters |
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non-Aurora and non-RDS Clusters?
sergiyvamz
reviewed
Nov 4, 2025
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| ## Using the Simple Read/Write Splitting Plugin against non-Aurora clusters | ||
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| The simple read/write splitting plugin can be used to switch between any two endpoints. If the endpoints do not direct to an Aurora database, ensure the property `verifyNewSrwConnections` is set to `false`. See [Limitations of verifyNewSrwConnections](UsingTheSimpleReadWriteSplittingPlugin.md#non-aurora-clusters) for details. |
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the same, Aurora or RDS Cluster
sergiyvamz
reviewed
Nov 4, 2025
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| # Simple Read/Write Splitting Plugin | |||
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| The simple read/write splitting plugin adds functionality to switch between endpoints via calls to the `Connection#setReadOnly` method. Based off the values provided in the properties, upon calling `setReadOnly(true)`, the plugin will connect to the given endpoint for read operations. When `setReadOnly(false)` is called, the plugin will connect to the given endpoint for write operations. Future calls to `setReadOnly` will switch between the established writer and reader connections according to the boolean argument you supply to the `setReadOnly` method. | |||
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We need to mention that this plugin doesn't rely on cluster topology but just on provided endpoints and their DNS resolution.
sergiyvamz
reviewed
Nov 4, 2025
| final Properties props = new Properties(); | ||
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| // Enable srw, failover, and efm2 plugins and set properties | ||
| props.setProperty(PropertyDefinition.PLUGINS.name, "srw,failover,efm2"); |
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Lets use failover2 to promote it.
sergiyvamz
reviewed
Nov 4, 2025
| final JdbcCallable<Void, SQLException> initHostProviderFunc) throws SQLException { | ||
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| this.hostListProviderService = hostListProviderService; | ||
| if (hostListProviderService.isStaticHostListProvider()) { |
sergiyvamz
reviewed
Nov 4, 2025
| this.pluginService = pluginService; | ||
| this.properties = properties; | ||
| this.writeEndpoint = writeEndpoint; | ||
| this.readEndpoint = SRW_READ_ENDPOINT.getString(properties); |
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Does it mean that SRW_READ_ENDPOINT is optional parameter?
sergiyvamz
reviewed
Nov 4, 2025
| } | ||
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| private boolean isWriteEndpoint(final @NonNull HostSpec hostSpec) { | ||
| return Objects.equals(hostSpec.getHost(), this.writeEndpoint); |
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We need to use getHostAndPort() and verify equalsIgnoreCase()
sergiyvamz
reviewed
Nov 4, 2025
| final Connection conn = this.pluginService.connect(this.writeEndpointHostSpec, this.properties, this); | ||
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| if (this.verifyNewConnections && this.pluginService.getHostRole(conn) != HostRole.WRITER) { | ||
| logAndThrowException( |
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Need retry logic as discussed
sergiyvamz
reviewed
Nov 4, 2025
| switchCurrentConnectionTo(this.writerConnection, writeEndpointHostSpec); | ||
| } | ||
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| private void getNewReaderConnection() throws SQLException { |
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Need retry logic as discussed
sergiyvamz
reviewed
Nov 4, 2025
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| public class SimpleReadWriteSplittingTest extends ReadWriteSplittingTests { | ||
| String pluginCode = "srw"; | ||
| String pluginCodesWithFailover = "failover,efm2,srw,initialConnection"; |
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Summary
introduces the Simple Read/Write Splitting Plugin (srw)
Description
an alternative to the existing Read/Write Splitting Plugin that connects directly to specified read and write endpoints
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By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.