comnetwork commented on code in PR #4940:
URL: https://github.com/apache/hbase/pull/4940#discussion_r1066726624
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hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RegionScannerImpl.java:
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@@ -426,6 +426,8 @@ private boolean nextInternal(List<Cell> results,
ScannerContext scannerContext)
// Used to check time limit
LimitScope limitScope = LimitScope.BETWEEN_CELLS;
+ checkpoint(State.START);
Review Comment:
@bbeaudreault , thank you for the elaborate work and I agree with your point
that adding a new boolean `checkpointEnabled` make the logic more clear.
> The contract is that if you are using checkpointing, you also need to call
retainBlock(). If you are not using checkpointing, you don't need to call
retainBlock().
I agree with the first part of the sentence, but have doubts about the
second. From you code, I think for scan by `RegionScannnerImpl`, `retainBlock`
is always needed to release blocks early, only when there is filter(especially
row level filter),we need checkpoint further to narrow the blocks which should
be retained after a row is filtered？I think we could only use `retainBlock`
for user scan which specifying columns but not has filters, so we don't need
to call `checkpoint`. If you agree with my point, I think the variable name
`boolean checkpointingEnabled` is not very appropriate, maybe
`earlyReleaseBlockEnabled` is more indicative of intentions？
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