Streaming support for JdbcOutboundGateway
#10061
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Fixes: spring-projects#3963 Introduce a `queryForStream` variable and a `streamConsumer` function in `JdbcOutboundGateway`. along with the underlying method `JdbcPollingChannelAdapter.doPollForStream`. when produce reply messages, if in stream mode, gateways always receives a empty list, process logic are moved to `streamConsumer`. Signed-off-by: Jiandong Ma <jiandong.ma.cn@gmail.com>
| @@ -53,6 +56,10 @@ public class JdbcOutboundGateway extends AbstractReplyProducingMessageHandler { | |||
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| private Integer maxRows; | |||
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| private boolean queryForStream = false; | |||
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| private Consumer<Object> streamConsumer; | |||
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here given Object type for Consumer, user have to do the type cast , which I am not very satisfied with this, because when set RowMapper, they already give return type.
I don't have a good way. I tried to put ?, but looks it can not be applied to Stream<?> .
| try (Stream<?> stream = this.poller.doPollForStream(sqlQueryParameterSource)) { | ||
| stream.forEach(this.streamConsumer); | ||
| } | ||
| return Collections.emptyList(); |
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Thank you for the effort, but this is not correct.
This is not a messaging way and this is not a goal of Spring Integration channel adapter.
If we go the of callback instead of sending a message to the channel, then there is no reason in using channel adapters.
Simple JdbcTemplate with its streaming API would do exactly the same without extra messaging layer to introduce for nothing.
Having a Stream as a message payload to produce from the channel adapter it totally fine.
However still all those questions are opened: the Stream has to be closed, not clear how to update entries of this stream to satisfy concurrent polling from the table. At the same time how do transactions behave with these opened (and possible updated) streams.
I general I suggest to close this PR since we are not going the way you suggest.
Sorry about that and thank you again for your effort!
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ohh, make sense, thank you for making me think in messaging way, I was wrong from the beginning.
Fixes: #3963
Introduce a
queryForStreamvariable and astreamConsumerfunction inJdbcOutboundGateway. along with the underlying methodJdbcPollingChannelAdapter.doPollForStream.when produce reply messages, if in stream mode, gateways always receives a empty list, process logic are moved to
streamConsumer.