THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
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For SQL, the default watermark emit-strategy is 'ON_PERIODICon-periodic', which can be set manually via table options and hint :
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-- configure in table options CREATE TABLE user_actions ( ... user_action_time TIMESTAMP(3), WATERMARK FOR user_action_time AS user_action_time - INTERVAL '5' SECOND ) WITH ( 'scan.watermark.emit.strategy'='ON_PERIODICon-periodic', ... ); -- use 'OPTIONS' hint select ... from source_table /*+ OPTIONS('scan.watermark.emit.strategy'='ON_PERIODICon-periodic') */ |
If the user wants to configure the 'ON_EVENTon-event' strategy, he/she can use table options or hint like this:
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-- configure in table options CREATE TABLE user_actions ( ... user_action_time TIMESTAMP(3), WATERMARK FOR user_action_time AS user_action_time - INTERVAL '5' SECOND ) WITH ( 'scan.watermark.emit.strategy'='ON_EVENTon-event', 'scan.watermark.emit.on-event.gap'='10000', ... ); -- use 'OPTIONS' hint select ... from source_table /*+ OPTIONS('scan.watermark.emit.strategy'='ON_EVENTon-event', 'scan.watermark.emit.on-event.gap'='10000') */ |
Note that the option 'scan.watermark.emit.on-event.gap' which is used to configure how many events to emit a watermark only works for 'ON_EVENTon-event' strategy, This option is not required, the default value is 1.
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-- configure in table options CREATE TABLE user_actions ( ... user_action_time TIMESTAMP(3), WATERMARK FOR user_action_time AS user_action_time - INTERVAL '5' SECOND ) WITH ( 'sourcescan.idle-timeout'='1min', ... ); -- use 'OPTIONS' hint select ... from source_table /*+ OPTIONS('sourcescan.idle-timeout'='1min') */ |
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-- configure in table options CREATE TABLE user_actions ( ... user_action_time TIMESTAMP(3), WATERMARK FOR user_action_time AS user_action_time - INTERVAL '5' SECOND ) WITH ( 'scan.watermark.alignment.group'='alignment-group-1', 'scan.watermark.alignment.max-drift'='1min', 'scan.watermark.alignment.update-interval'='1s', ... ); -- use 'OPTIONS' hint select ... from source_table /*+ OPTIONS('scan.watermark.alignment.group'='alignment-group-1', 'scan.watermark.alignment.max-drift'='1min', 'scan.watermark.alignment.update-interval'='1s') */ |
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All the options described above :
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'scan.watermark.emit.strategy'='ON_EVENTon-event', 'scan.watermark.emit.on-event.gap'='10000', 'sourcescan.idle-timeout'='1min', 'scan.watermark.alignment.group'='alignment-group-1', 'scan.watermark.alignment.max-drift'='1min', 'scan.watermark.alignment.update-interval'='1s' |
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