hit-lacus commented on a change in pull request #1662:
URL: https://github.com/apache/kylin/pull/1662#discussion_r655095908
##########
File path:
core-common/src/main/java/org/apache/kylin/common/KylinConfigBase.java
##########
@@ -3125,4 +3125,32 @@ public int getRepartitionNumAfterEncode() {
public boolean rePartitionEncodedDatasetWithRowKey() {
return
Boolean.valueOf(getOptional("kylin.engine.spark.repartition.encoded.dataset",
"false"));
}
+
+ /*
+ * Detect dataset skew in dictionary encode step.
+ * */
+ public boolean detectDataSkewInDictEncodingEnabled() {
+ return
Boolean.valueOf(getOptional("detect.data.skew.in.dict.encoding", "false"));
+ }
+
+ /*
+ * In some data skew cases, the repartition step during dictionary encoding
will be slow.
+ * We can choose to sample from the dataset to detect skewed. This
configuration is used to set the sample rate.
+ * */
+ public double sampleRateInEncodingSkewDetection() {
+ return
Double.valueOf(getOptional("sample.rate.in.encoding.skew.detection", "0.1"));
+ }
+
+ /*
+ * In KYLIN4, dictionaries are hashed into several buckets, column data are
repartitioned by the same hash algorithm
+ * during encoding step too. In data skew cases, the repartition step will
be very slow. Kylin will automatically
+ * sample from the source to detect skewed data and repartition these
skewed data to random partitions.
+ * This configuration is used to set the skew data threshhold, valued from
0 to 1.
+ * e.g.
+ * if you set this value to 0.05, for each value that takes up more than
5% percent of the total will be regarded
+ * as skew data, as a result the skewed data will be no more than 20
records
+ * */
+ public double skewOccupationThreshHold() {
+ return Double.valueOf(getOptional("skew.occupation.threshhold",
"0.05"));
Review comment:
`kylin.dictionary.data.skew.key.percentage.threshhold`
##########
File path:
core-common/src/main/java/org/apache/kylin/common/KylinConfigBase.java
##########
@@ -3125,4 +3125,32 @@ public int getRepartitionNumAfterEncode() {
public boolean rePartitionEncodedDatasetWithRowKey() {
return
Boolean.valueOf(getOptional("kylin.engine.spark.repartition.encoded.dataset",
"false"));
}
+
+ /*
+ * Detect dataset skew in dictionary encode step.
+ * */
+ public boolean detectDataSkewInDictEncodingEnabled() {
+ return
Boolean.valueOf(getOptional("detect.data.skew.in.dict.encoding", "false"));
+ }
+
+ /*
+ * In some data skew cases, the repartition step during dictionary encoding
will be slow.
+ * We can choose to sample from the dataset to detect skewed. This
configuration is used to set the sample rate.
+ * */
+ public double sampleRateInEncodingSkewDetection() {
Review comment:
`kylin.dictionary.data.skew.detect.sample.rate`
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