[EdwwgWgR] Stream schema results in batches of batchSize #435
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Lojjs
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Jun 12, 2023
common/src/main/java/apoc/export/cypher/formatter/AbstractCypherFormatter.java
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| @@ -388,11 +389,10 @@ private long countArtificialUniques(Iterable<Node> n) { | |||
| private long getArtificialUniques(Node node, long artificialUniques) { | |||
| Iterator<Label> labels = node.getLabels().iterator(); | |||
| boolean uniqueFound = false; | |||
| while (labels.hasNext()) { | |||
| while (labels.hasNext() && !uniqueFound) { | |||
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Was this bug fix only a speed-up or can we add a test for it?
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It was both I guess, I added it for the speed, although the bug wouldn't have affected the correctness of the outputted queries. I can add a test for it though :)
Lojjs
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Jun 12, 2023
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The nodes and relationships weren't streaming in batches which caused an out of memory error as APOC tried to hold all the nodes/rels in memory.
Differences:
As we take nodes sequentially, there may be more groups of unwinds as previously all nodes of that label was found and in one unwind vs now they may end up in different statements due to batching (similar for rels)
There was a check for rels that assumed we knew all rels and could optimize on whether or not to filter on id, however, a batch only knows about that batch and not all rels, so that assumption no longer holds
Schema will stream before moving on to nodes, this was intended by the looks of it already, just missed the call to accept the batch
There was a bug around the counting of needed unique labels as the for loop didn't stop when it hit true (found unique), this has been corrected
I didn't add an out of memory test as I felt like this would just slow our testing down. But I did test this manually on a graph which was roughly 2.5 million nodes and 2 million rels (2x bigger than db which was reported for this to be failing on). The version without the fix doesn't work, the version with the fix did :)