ES|QL: account for page overhead when calculating memory used by blocks #108347
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luigidellaquila
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May 7, 2024
| + RamUsageEstimator.shallowSizeOfInstance(BooleanVectorBlock.class); | ||
| + RamUsageEstimator.shallowSizeOfInstance(BooleanVectorBlock.class) | ||
| // TODO: remove this if/when we account for memory used by Pages | ||
| + RamUsageEstimator.NUM_BYTES_OBJECT_ALIGNMENT; |
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Strictly, this should be NUM_BYTES_OBJECT_REF, but it would need further alignment to object size, so practically it would make no difference, to the cost of one more operation.
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I'm not 100% sure we should account for the refs this way, but it does seem like a reasonable solution, at least for a while.
I think we should make a constant in Block for this rather than use NUM_BYTES_OBJECT_ALIGNMENT - that one feels a little random. Or, if it is random, we can explain why it's the right value on the constant.
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Pinging @elastic/es-analytical-engine (Team:Analytics) |
markjhoy
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May 9, 2024
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ES|QL accounts for memory used by single blocks, but it doesn't account for the Page.
In particular, Page.blocks array can have a significant footprint when we have thousands of columns in the result set.
Accounting for memory used by pages is difficult at this stage, so for now we'll approximate it adding some overhead to each block, assuming that a block will typically be linked to a single page.
Fixes #108104