R2DBC - MssqlNonTransientException causing onErrorDropped - spring-data-r2dbc

Question

I am quite fresh in reactive world and recently come across quite odd problem, context:
using spring data with R2DBC, on MS SQL
running on SB 2.3, OpenJDK 14 (dependencies below)
using transactional via annotations
using "repositories" built purely on DatabaseClient (code sample below)
and while trying to execute:
delete from master.abc.DEF, followed by
an invalid, on purpose, insert I get following exception:
2020-06-04 00:46:16.345 ERROR [....] 56223 --- [actor-tcp-nio-2] reactor.core.publisher.Operators : Operator called default onErrorDropped
io.r2dbc.mssql.ExceptionFactory$MssqlNonTransientException: Cannot insert the value NULL into column 'some_id', table 'master.abc.DEF'; column does not allow nulls. INSERT fails.
at io.r2dbc.mssql.ExceptionFactory.createException(ExceptionFactory.java:152)
Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException:
Assembly trace from producer [reactor.core.publisher.FluxLift] :
reactor.core.publisher.Flux.doOnComplete
io.r2dbc.mssql.RpcQueryMessageFlow.exchange(RpcQueryMessageFlow.java:154)
Error has been observed at the following site(s):
|_ Flux.doOnComplete ⇢ at io.r2dbc.mssql.RpcQueryMessageFlow.exchange(RpcQueryMessageFlow.java:154)
|_ Flux.filter ⇢ at io.r2dbc.mssql.RpcQueryMessageFlow.exchange(RpcQueryMessageFlow.java:160)
|_ Flux.doOnCancel ⇢ at io.r2dbc.mssql.RpcQueryMessageFlow.exchange(RpcQueryMessageFlow.java:161)
|_ Flux.doOnSubscribe ⇢ at io.r2dbc.mssql.RpcQueryMessageFlow.exchange(RpcQueryMessageFlow.java:163)
Stack trace:
at io.r2dbc.mssql.ExceptionFactory.createException(ExceptionFactory.java:152)
at io.r2dbc.mssql.ExceptionFactory.createException(ExceptionFactory.java:181)
at io.r2dbc.mssql.RpcQueryMessageFlow.lambda$exchange$1(RpcQueryMessageFlow.java:148)
at reactor.core.publisher.FluxHandle$HandleSubscriber.onNext(FluxHandle.java:96)
at reactor.core.publisher.EmitterProcessor.drain(EmitterProcessor.java:426)
at reactor.core.publisher.EmitterProcessor.onNext(EmitterProcessor.java:268)
at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onNext(ScopePassingSpanSubscriber.java:90)
at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.onNext(FluxPeekFuseable.java:203)
at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onNext(ScopePassingSpanSubscriber.java:90)
at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.onNext(FluxPeekFuseable.java:203)
at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onNext(ScopePassingSpanSubscriber.java:90)
at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.onNext(FluxPeekFuseable.java:203)
at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onNext(ScopePassingSpanSubscriber.java:90)
at reactor.core.publisher.FluxHandleFuseable$HandleFuseableSubscriber.onNext(FluxHandleFuseable.java:178)
at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onNext(ScopePassingSpanSubscriber.java:90)
at reactor.core.publisher.MonoFlatMapMany$FlatMapManyInner.onNext(MonoFlatMapMany.java:242)
at org.springframework.cloud.sleuth.instrument.reactor.ScopePassingSpanSubscriber.onNext(ScopePassingSpanSubscriber.java:90)
at reactor.core.publisher.FluxPeek$PeekSubscriber.onNext(FluxPeek.java:192)
at reactor.core.publisher.EmitterProcessor.drain(EmitterProcessor.java:426)
at reactor.core.publisher.EmitterProcessor.onNext(EmitterProcessor.java:268)
at io.r2dbc.mssql.client.ReactorNettyClient$1.next(ReactorNettyClient.java:237)
at io.r2dbc.mssql.client.ReactorNettyClient$1.next(ReactorNettyClient.java:197)
at io.r2dbc.mssql.message.token.Tabular$TabularDecoder.decode(Tabular.java:425)
at io.r2dbc.mssql.client.ConnectionState$4$1.decode(ConnectionState.java:206)
at io.r2dbc.mssql.client.StreamDecoder.withState(StreamDecoder.java:137)
at io.r2dbc.mssql.client.StreamDecoder.decode(StreamDecoder.java:109)
at io.r2dbc.mssql.client.ReactorNettyClient.lambda$new$6(ReactorNettyClient.java:247)
at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.onNext(FluxPeekFuseable.java:189)
at reactor.netty.channel.FluxReceive.drainReceiver(FluxReceive.java:220)
at reactor.netty.channel.FluxReceive.onInboundNext(FluxReceive.java:354)
at reactor.netty.channel.ChannelOperations.onInboundNext(ChannelOperations.java:352)
at reactor.netty.channel.ChannelOperationsHandler.channelRead(ChannelOperationsHandler.java:96)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
at io.netty.channel.ChannelInboundHandlerAdapter.channelRead(ChannelInboundHandlerAdapter.java:93)
at io.r2dbc.mssql.client.ssl.TdsSslHandler.channelRead(TdsSslHandler.java:402)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919)
at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:163)
at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:714)
at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:650)
at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:576)
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:493)
at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989)
at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
at java.base/java.lang.Thread.run(Thread.java:832)
and due to that - transaction is not rollbacked and underlying table is locked :/
The flow (simplified) is:
#Transactional
public Mono<X> replaceX(final String someX)
return someRepository.deleteByX(someX)
.then(...making a webClient-based-call)
.flatMap(input -> someRepository.create(detailsFrom(input)))
....
Adding Hooks.onErrorDropped(error -> ... in a way solves the problem, but that does not seem as a proper solution and I am still wondering what could be the actual root cause - I assume my code/approach rather then r2dbc.
pom snippet
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.3.0.RELEASE</version>
<relativePath/>
</parent>
...
<java.version>14</java.version>
<!-- dependencies version -->
<spring-sleuth.version>2.2.2.RELEASE</spring-sleuth.version>
<reactor-tools.version>3.3.5.RELEASE</reactor-tools.version>
<reactor-tools-blockhound.version>1.0.3.RELEASE</reactor-tools-blockhound.version>
<mssql-jdbc.version>7.4.1.jre11</mssql-jdbc.version> <!-- override spring's default -->
<hibernate-validator.version>6.1.5.Final</hibernate-validator.version>
<springdoc-webflux.version>1.3.2</springdoc-webflux.version>
<logstash-logback.version>6.3</logstash-logback.version>
...
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-r2dbc</artifactId>
</dependency>
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>io.r2dbc</groupId>
<artifactId>r2dbc-h2</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>com.microsoft.sqlserver</groupId>
<artifactId>mssql-jdbc</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>io.r2dbc</groupId>
<artifactId>r2dbc-mssql</artifactId>
<scope>runtime</scope>
</dependency>
repository methods (conceptual):
public Mono<Void> deleteByX(final String x) {
return this.databaseClient.delete()
.from(X.class)
.matching(where("x").is(x))
.then();
}
public Mono<Long> create(final #NonNull X x) {
return this.databaseClient.insert()
.into(X.class)
.using(x)
.map(row -> row.get(0, Long.class))
.first();
}