ESQL: Track memory in evaluators (#133392) #133593
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If you write very very large ESQL queries you can spend a lot of memory on the expression evaluators themselves. You can certainly do it in real life, but our tests do something like: ``` FROM foo | EVAL a0001 = n + 1 | EVAL a0002 = a0001 + 1 | EVAL a0003 = a0002 + 1 ... | EVAL a5000 = a4999 + 1 | STATS MAX(a5000) ``` Each evaluator costs like 200 bytes a pop. For thousands of evaluators this adds up. So! We have to track it. Nhat had suggested charging a flat 200 bytes a pop. I thought about it and decided that it'd be pretty easy to get the actual size. Most of the evaluators are generated and it's a fairly small generated change to pick that up. So I did. We *do* build the evaluators before we cost them, but that's fine because they are very very small. So long as we account for them, I think it's safe.
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sarog
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Sep 11, 2025
If you write very very large ESQL queries you can spend a lot of memory on the expression evaluators themselves. You can certainly do it in real life, but our tests do something like: ``` FROM foo | EVAL a0001 = n + 1 | EVAL a0002 = a0001 + 1 | EVAL a0003 = a0002 + 1 ... | EVAL a5000 = a4999 + 1 | STATS MAX(a5000) ``` Each evaluator costs like 200 bytes a pop. For thousands of evaluators this adds up. So! We have to track it. Nhat had suggested charging a flat 200 bytes a pop. I thought about it and decided that it'd be pretty easy to get the actual size. Most of the evaluators are generated and it's a fairly small generated change to pick that up. So I did. We *do* build the evaluators before we cost them, but that's fine because they are very very small. So long as we account for them, I think it's safe.
sarog
pushed a commit
to portsbuild/elasticsearch
that referenced
this pull request
Sep 19, 2025
If you write very very large ESQL queries you can spend a lot of memory on the expression evaluators themselves. You can certainly do it in real life, but our tests do something like: ``` FROM foo | EVAL a0001 = n + 1 | EVAL a0002 = a0001 + 1 | EVAL a0003 = a0002 + 1 ... | EVAL a5000 = a4999 + 1 | STATS MAX(a5000) ``` Each evaluator costs like 200 bytes a pop. For thousands of evaluators this adds up. So! We have to track it. Nhat had suggested charging a flat 200 bytes a pop. I thought about it and decided that it'd be pretty easy to get the actual size. Most of the evaluators are generated and it's a fairly small generated change to pick that up. So I did. We *do* build the evaluators before we cost them, but that's fine because they are very very small. So long as we account for them, I think it's safe.
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If you write very very large ESQL queries you can spend a lot of memory on the expression evaluators themselves. You can certainly do it in real life, but our tests do something like:
Each evaluator costs like 200 bytes a pop. For thousands of evaluators this adds up. So! We have to track it.
Nhat had suggested charging a flat 200 bytes a pop. I thought about it and decided that it'd be pretty easy to get the actual size. Most of the evaluators are generated and it's a fairly small generated change to pick that up. So I did.
We do build the evaluators before we cost them, but that's fine because they are very very small. So long as we account for them, I think it's safe.