Yingyi Bu has posted comments on this change.
Change subject: Avoid always merging old components in prefix policy
......................................................................
Patch Set 7:
A revised version that fixes a bug and skips looking ahead earlier:
private Pair<Integer, Integer>
getMergableComponentsIndex(List<ILSMDiskComponent> immutableComponents) {
int numComponents = immutableComponents.size();
for (int i = 0; i < numComponents; i++) {
long startComponentSize =
immutableComponents.get(i).getComponentSize();
if (immutableComponents.get(i).getComponentSize() >
maxMergableComponentSize
|| immutableComponents.get(i).getState() !=
ComponentState.READABLE_UNWRITABLE) {
continue;
}
long totalSize = startComponentSize;
int j = i + 1;
boolean mergeable = true;
for (; j < numComponents; j++) {
long componentSize =
immutableComponents.get(j).getComponentSize();
if (componentSize > maxMergableComponentSize
|| immutableComponents.get(j).getState() !=
ComponentState.READABLE_UNWRITABLE) {
// skip unmergeable components if any
break;
}
totalSize += componentSize;
mergeable =
startComponentSize < MAX_MERGABLE_COMPONENT_SIZE_RATIO
* (totalSize - startComponentSize);
if (totalSize > maxMergableComponentSize && mergeable) {
// If the ratio check passes and total size exceeds the
threshold, we return this sequence
return Pair.of(i, j);
}
// Stops search if the ratio threshold cannot be met.
if (startComponentSize >= MAX_MERGABLE_COMPONENT_SIZE_RATIO
* (totalSize + componentSize * (numComponents - j - 1)
- startComponentSize)) {
break;
}
}
if (j != numComponents) {
continue;
}
if (numComponents - i >= maxToleranceComponentCount && mergeable) {
// If it's the last component, component count exceeds the
threshold, the ratio check passes,
// then we return this sequence.
return Pair.of(i, numComponents - 1);
}
// if we reach the last component, but there are not enough
components to merge,
// then we don't need to check i+1 th component
if (numComponents - i <= maxToleranceComponentCount) {
return null;
}
}
return null;
}
--
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Gerrit-MessageType: comment
Gerrit-Change-Id: I464da3fed38cded0aee7b319a35664eae069a2ba
Gerrit-PatchSet: 7
Gerrit-Project: asterixdb
Gerrit-Branch: master
Gerrit-Owner: Luo Chen <[email protected]>
Gerrit-Reviewer: Ian Maxon <[email protected]>
Gerrit-Reviewer: Jenkins <[email protected]>
Gerrit-Reviewer: Jianfeng Jia <[email protected]>
Gerrit-Reviewer: Luo Chen <[email protected]>
Gerrit-Reviewer: Yingyi Bu <[email protected]>
Gerrit-Reviewer: abdullah alamoudi <[email protected]>
Gerrit-HasComments: No
