Create better plans for NULL comparisons#6133
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harshit-gangal merged 4 commits intovitessio:masterfrom Apr 30, 2020
Merged
Create better plans for NULL comparisons#6133harshit-gangal merged 4 commits intovitessio:masterfrom
harshit-gangal merged 4 commits intovitessio:masterfrom
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Signed-off-by: Andres Taylor <andres@planetscale.com>
Signed-off-by: Andres Taylor <andres@planetscale.com>
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nice to have an endtoend test for it.
Signed-off-by: Harshit Gangal <harshit@planetscale.com>
Signed-off-by: Harshit Gangal <harshit@planetscale.com>
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nit: it will be nice to document the problem in the PR description. |
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When building a VTgate query plan, if we are dealing with a comparison against a literal NULL value, previously we were just giving up and falling back on a scatter.
This change adds a new route opcode for queries that are known to never return values (
SelectNone), which will be used when an equality with null is found in the list of predicates in the WHERE clause. It also handlesIS NULLwith aSelectEqual[Unique]when the vindex supports null values.