mikemccand commented on code in PR #13253:
URL: https://github.com/apache/lucene/pull/13253#discussion_r1576373763
##########
lucene/core/src/java/org/apache/lucene/codecs/lucene90/blocktree/SegmentTermsEnumFrame.java:
##########
@@ -287,6 +287,68 @@ void rewind() {
*/
}
+ // Only rewind, don't force reload block.
+ // Reset readers' position, don't read, decompress.
+ // Current term greater than target, reduce endCount.
+ void rewindWithoutReload() {
+ // Set nextEnt to 0, to prevent force load.
+ nextEnt = 0;
+ suffixesReader.setPosition(0);
+ suffixLengthsReader.setPosition(0);
+ statsReader.setPosition(0);
+ bytesReader.setPosition(0);
+
+ // TODO: Since we only rewind without reload for fist
floor(currentFrame.fp ==
Review Comment:
`fist` -> `first`
##########
lucene/core/src/java/org/apache/lucene/codecs/lucene90/blocktree/SegmentTermsEnum.java:
##########
@@ -434,8 +436,29 @@ public boolean seekExact(BytesRef target) throws
IOException {
// System.out.println(" target is before current (shares
prefixLen=" + targetUpto + ");
// rewind frame ord=" + lastFrame.ord);
// }
+
+ // We got lastFrame by comparing target and term, and target less than
last seeked term in
+ // currentFrame. If lastFrame's fp is same with currentFrame's fp, we
can reduce entCount to
+ // nextEnt.
+ boolean currentIsLast = currentFrame.fp == lastFrame.fp;
currentFrame = lastFrame;
- currentFrame.rewind();
+
+ // Only rewindWithoutReload for non-floor block or first floor block.
+ // TODO: We need currentFrame's first entry to judge whether we can
rewindWithoutReload for
+ // non-first floor blocks.
Review Comment:
The FST terms index has a lower bound `BytesRef` pointer to the start term
of all floor multi-blocks, but I don't think we save this anywhere today.
Let's leave it as a future `TODO`?
##########
lucene/core/src/java/org/apache/lucene/codecs/lucene90/blocktree/SegmentTermsEnum.java:
##########
@@ -518,7 +541,20 @@ public boolean seekExact(BytesRef target) throws
IOException {
currentFrame.loadBlock();
+ // We still stay on withOutReload frame, reduce entCount to nextEnt.
+ int origEntCount = -1;
+ if (currentFrame.fp == withOutReloadFp && origNextEnt != 0) {
+ origEntCount = currentFrame.entCount;
+ currentFrame.entCount = origNextEnt;
+ }
+
final SeekStatus result = currentFrame.scanToTerm(target, true);
+
+ // Revert entCount to origEntCount.
Review Comment:
`Revert` -> `Restore`?
##########
lucene/core/src/java/org/apache/lucene/codecs/lucene90/blocktree/SegmentTermsEnum.java:
##########
@@ -573,7 +609,20 @@ public boolean seekExact(BytesRef target) throws
IOException {
currentFrame.loadBlock();
+ // We still stay on withOutReload frame, reduce entCount to nextEnt.
+ int origEntCount = -1;
+ if (currentFrame.fp == withOutReloadFp && origNextEnt != 0) {
+ origEntCount = currentFrame.entCount;
+ currentFrame.entCount = origNextEnt;
+ }
+
final SeekStatus result = currentFrame.scanToTerm(target, true);
+
+ // Revert entCount to origEntCount.
Review Comment:
`Revert` -> `Restore`?
##########
lucene/core/src/java/org/apache/lucene/codecs/lucene90/blocktree/SegmentTermsEnum.java:
##########
@@ -710,8 +761,28 @@ public SeekStatus seekCeil(BytesRef target) throws
IOException {
// System.out.println(" target is before current (shares prefixLen="
+ targetUpto + ");
// rewind frame ord=" + lastFrame.ord);
// }
+
+ // We got lastFrame by comparing target and term, and target less than
last seeked term in
+ // currentFrame. If lastFrame's fp is same with currentFrame's fp, we
can reduce entCount to
+ // nextEnt.
Review Comment:
Maybe change to `we can rewind without reloading`? We don't seem to reduce
`entCount` anymore?
##########
lucene/core/src/java/org/apache/lucene/codecs/lucene90/blocktree/SegmentTermsEnum.java:
##########
@@ -434,8 +436,29 @@ public boolean seekExact(BytesRef target) throws
IOException {
// System.out.println(" target is before current (shares
prefixLen=" + targetUpto + ");
// rewind frame ord=" + lastFrame.ord);
// }
+
+ // We got lastFrame by comparing target and term, and target less than
last seeked term in
+ // currentFrame. If lastFrame's fp is same with currentFrame's fp, we
can reduce entCount to
+ // nextEnt.
+ boolean currentIsLast = currentFrame.fp == lastFrame.fp;
currentFrame = lastFrame;
- currentFrame.rewind();
+
+ // Only rewindWithoutReload for non-floor block or first floor block.
+ // TODO: We need currentFrame's first entry to judge whether we can
rewindWithoutReload for
+ // non-first floor blocks.
+ if (currentFrame.fp != currentFrame.fpOrig
+ || currentFrame.entCount == 0
+ || currentFrame.nextEnt == -1) {
+ currentFrame.rewind();
+ } else {
+ // Prepare to reduce entCount.
+ if (currentIsLast && currentFrame.isLeafBlock) {
Review Comment:
I am confused why there are two cases under the `rewindWithoutReload` case.
One case you can roll back `entCount` temporarily, because you know the target
term is before the current term? And in the 2nd case, you don't know that, but
you do know the target term is in this current block? But then why are we even
rewinding?
##########
lucene/core/src/java/org/apache/lucene/codecs/lucene90/blocktree/SegmentTermsEnum.java:
##########
@@ -434,8 +436,29 @@ public boolean seekExact(BytesRef target) throws
IOException {
// System.out.println(" target is before current (shares
prefixLen=" + targetUpto + ");
// rewind frame ord=" + lastFrame.ord);
// }
+
+ // We got lastFrame by comparing target and term, and target less than
last seeked term in
+ // currentFrame. If lastFrame's fp is same with currentFrame's fp, we
can reduce entCount to
+ // nextEnt.
+ boolean currentIsLast = currentFrame.fp == lastFrame.fp;
currentFrame = lastFrame;
- currentFrame.rewind();
+
+ // Only rewindWithoutReload for non-floor block or first floor block.
+ // TODO: We need currentFrame's first entry to judge whether we can
rewindWithoutReload for
+ // non-first floor blocks.
+ if (currentFrame.fp != currentFrame.fpOrig
Review Comment:
Could you add comment for each of these reasons to still reload the frame?
E.g.:
`currentFrame.fp != currentFrame.fpOrig // this is a floor multi-block and
not the first one``
`currentFrame.entCount == 0 // why does this happen?`
etc.?
I don't understand when/why the 2nd two conditions occur.
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