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Posted to dev@orc.apache.org by GitBox <gi...@apache.org> on 2021/09/14 05:46:36 UTC
[GitHub] [orc] guiyanakuang opened a new pull request #907: ORC-992: Reached max repeat length, we can directly decide to use DELTA encoding
guiyanakuang opened a new pull request #907:
URL: https://github.com/apache/orc/pull/907
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### What changes were proposed in this pull request?
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Reached max repeat length, we can directly decide to use DELTA encoding.
The computeZigZagLiterals, zzBits100p, and determine isFixedDelta within the determineEncoding method are all redundant in the current case.
Similar practices.
RunLengthIntegerWriterV2.java 767-775
```java
if (fixedRunLength >= MIN_REPEAT) {
if (fixedRunLength <= MAX_SHORT_REPEAT_LENGTH) {
encoding = EncodingType.SHORT_REPEAT;
} else {
encoding = EncodingType.DELTA;
isFixedDelta = true;
}
writeValues();
}
```
### Why are the changes needed?
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Please clarify why the changes are needed. For instance,
1. If you propose a new API, clarify the use case for a new API.
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Optimization for reached max repeat length.
### How was this patch tested?
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Pass the CIs.
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[GitHub] [orc] guiyanakuang commented on pull request #907: ORC-992: Reached max repeat length, we can directly decide to use DELTA encoding
Posted by GitBox <gi...@apache.org>.
guiyanakuang commented on pull request #907:
URL: https://github.com/apache/orc/pull/907#issuecomment-922565756
> Sorry for late review. BTW, do we need to update only `encoding` and `isFixedDelta`? What about other variables like `fixedDelta`?
`fixedDelta` initialized to 0, and `writeValues()` ends with a call to `clear()` to set the necessary variables to their default values. `fixedDelta=0` is exactly what we need. This is also the case with `bitsDeltaMax`.
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[GitHub] [orc] guiyanakuang commented on a change in pull request #907: ORC-992: Reached max repeat length, we can directly decide to use DELTA encoding
Posted by GitBox <gi...@apache.org>.
guiyanakuang commented on a change in pull request #907:
URL: https://github.com/apache/orc/pull/907#discussion_r711835232
##########
File path: java/core/src/java/org/apache/orc/impl/RunLengthIntegerWriterV2.java
##########
@@ -755,7 +755,8 @@ public void write(long val) throws IOException {
// if fixed runs reached max repeat length then write values
if (fixedRunLength == MAX_SCOPE) {
- determineEncoding();
+ encoding = EncodingType.DELTA;
+ isFixedDelta = true;
Review comment:
However, java and C++ have different styles of processing
```java
//Java
if (prevDelta == 0 && currentDelta == 0) {
// fixed delta run
} else {
// variable delta run
}
```
```C++
//c++
if (prevDelta == 0 && currentDelta == 0) {
// fixed delta run
return;
}
// variable delta run
```
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[GitHub] [orc] dongjoon-hyun merged pull request #907: ORC-992: Reached max repeat length, we can directly decide to use DELTA encoding
Posted by GitBox <gi...@apache.org>.
dongjoon-hyun merged pull request #907:
URL: https://github.com/apache/orc/pull/907
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[GitHub] [orc] guiyanakuang commented on a change in pull request #907: ORC-992: Reached max repeat length, we can directly decide to use DELTA encoding
Posted by GitBox <gi...@apache.org>.
guiyanakuang commented on a change in pull request #907:
URL: https://github.com/apache/orc/pull/907#discussion_r711830334
##########
File path: java/core/src/java/org/apache/orc/impl/RunLengthIntegerWriterV2.java
##########
@@ -755,7 +755,8 @@ public void write(long val) throws IOException {
// if fixed runs reached max repeat length then write values
if (fixedRunLength == MAX_SCOPE) {
- determineEncoding();
+ encoding = EncodingType.DELTA;
+ isFixedDelta = true;
Review comment:
I think the `else` on line 762 separates the fixed delta run from the variable delta run. 763 This is followed by the variable delta run.
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[GitHub] [orc] dongjoon-hyun commented on a change in pull request #907: ORC-992: Reached max repeat length, we can directly decide to use DELTA encoding
Posted by GitBox <gi...@apache.org>.
dongjoon-hyun commented on a change in pull request #907:
URL: https://github.com/apache/orc/pull/907#discussion_r711802547
##########
File path: c++/src/RleEncoderV2.cc
##########
@@ -124,7 +124,8 @@ void RleEncoderV2::write(int64_t val) {
}
if (fixedRunLength == MAX_LITERAL_SIZE) {
- determineEncoding(option);
+ option.encoding = DELTA;
+ option.isFixedDelta = true;
Review comment:
After this PR, the comments at line 134 will become obsolete.
> // case 2: variable delta run
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[GitHub] [orc] guiyanakuang commented on a change in pull request #907: ORC-992: Reached max repeat length, we can directly decide to use DELTA encoding
Posted by GitBox <gi...@apache.org>.
guiyanakuang commented on a change in pull request #907:
URL: https://github.com/apache/orc/pull/907#discussion_r711829520
##########
File path: c++/src/RleEncoderV2.cc
##########
@@ -124,7 +124,8 @@ void RleEncoderV2::write(int64_t val) {
}
if (fixedRunLength == MAX_LITERAL_SIZE) {
- determineEncoding(option);
+ option.encoding = DELTA;
+ option.isFixedDelta = true;
Review comment:
The return on line 131 has ended the handling of the fixed delta run case. I think the comment on line 134 is not obsolete. The following is exactly how to handle variable delta run.
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[GitHub] [orc] dongjoon-hyun commented on a change in pull request #907: ORC-992: Reached max repeat length, we can directly decide to use DELTA encoding
Posted by GitBox <gi...@apache.org>.
dongjoon-hyun commented on a change in pull request #907:
URL: https://github.com/apache/orc/pull/907#discussion_r711802646
##########
File path: java/core/src/java/org/apache/orc/impl/RunLengthIntegerWriterV2.java
##########
@@ -755,7 +755,8 @@ public void write(long val) throws IOException {
// if fixed runs reached max repeat length then write values
if (fixedRunLength == MAX_SCOPE) {
- determineEncoding();
+ encoding = EncodingType.DELTA;
+ isFixedDelta = true;
Review comment:
Ditto. This PR makes line 763 a little obsolete.
> // variable delta run
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[GitHub] [orc] guiyanakuang commented on pull request #907: ORC-992: Reached max repeat length, we can directly decide to use DELTA encoding
Posted by GitBox <gi...@apache.org>.
guiyanakuang commented on pull request #907:
URL: https://github.com/apache/orc/pull/907#issuecomment-922165361
@dongjoon-hyun @wgtmac Can you help review this, please?
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