[SQL] Preliminary support for bounded memory computation on streams #1197
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Signed-off-by: Mihai Budiu <mbudiu@feldera.com>
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Here is a picture of the topology of the generated code for a program with group-by aggregate |
Signed-off-by: Mihai Budiu <mbudiu@feldera.com>
ryzhyk
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…1197) * [SQL] Preliminary support for bounded memory computation on streams Signed-off-by: Mihai Budiu <mbudiu@feldera.com>
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Is this a user-visible change (yes/no): no
This implementation uses the DBSP
integrate_trace_retain_keysoperator to throw away group keys that will never be updated. It is used in conjunction with the lateness dataflow analysis to control the memory consumption of streams of monotone values. That operator has a very funky semantics, so the hope is that at some point we can do this in a simpler way.This implementation is incomplete; it only handles (group-by)+aggregate operators and it is only limited to some simple graph topologies.
We still have to handle: