fixed bug limit push down of index scan. #2905
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src/storage/exec/IndexEdgeNode.h
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| @@ -66,6 +62,7 @@ class IndexEdgeNode final : public RelNode<T> { | |||
| edges.emplace_back(std::move(edge)); | |||
| iter->next(); | |||
| } | |||
| int64_t count = 1; | |||
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Why count is initialized with 1?
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Why
countis initialized with 1?
limit has three types of boundary value:
limit == -1, This means no limits and is a default value.
limit == 0, This means don't need to return any data. this one don't need to any data scan. handler in LookupProcessor.cpp:26
limit > 0, true used for limit. the count number begin with 1.
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I mean you should initialize with 0? See line 82 limit_ > 0 && ++count > limit_
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It looks ok
Because here put the data in first, and then judge
If count is initialized to 0, the code on line 82 is as follows:
if (limit_> 0 && ++count >= limit_) {
break;
}
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But I prefer to initialize count to 0, wdyt?
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But I prefer to initialize
countto 0, wdyt?
Aha, the point of ambiguity is here, you are all right. the code readability is a bit low.
Changed the init count to 0.
|
Close #2583 |
| auto indexScan = std::make_unique<IndexScanNode<IndexID>>( | ||
| context_.get(), indexId, std::move(colHints), limit_); | ||
| auto indexScan = | ||
| std::make_unique<IndexScanNode<IndexID>>(context_.get(), indexId, std::move(colHints)); |
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Why doesn't this plan need limit?
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Why doesn't this plan need
limit?
if FilterNode exists. will check the limit in FilterNode. skip the IndexScanNode.
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related PR #2796
The logic of the previous PR is simple, handles limits during the index scan phase. Scanning filter, data validity, etc., are not considered.
for this PR , The items below will be covered by：
Temporarily unsupported
Limit + Paging Scanis integrated