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Posted to commits@doris.apache.org by GitBox <gi...@apache.org> on 2022/10/09 11:17:52 UTC
[GitHub] [doris] morrySnow commented on a diff in pull request #10170: [Enhancement](optimizer) Support select table sample
morrySnow commented on code in PR #10170:
URL: https://github.com/apache/doris/pull/10170#discussion_r990772731
##########
fe/fe-core/src/main/java/org/apache/doris/analysis/TableRef.java:
##########
@@ -197,17 +205,49 @@ protected TableRef(TableRef other) {
lateralViewRefs.add((LateralViewRef) viewRef.clone());
}
}
+ if (other.sampleTabletIds.size() != 0) {
Review Comment:
why not copy if size is 0?
##########
fe/fe-core/src/main/java/org/apache/doris/analysis/TableSample.java:
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@@ -0,0 +1,101 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package org.apache.doris.analysis;
+
+import org.apache.doris.common.AnalysisException;
+
+/*
+ * To represent following stmt:
+ * TABLESAMPLE (10 PERCENT)
+ * TABLESAMPLE (100 ROWS)
+ * TABLESAMPLE (10 PERCENT) REPEATABLE (123)
+ * TABLESAMPLE (100 ROWS) REPEATABLE (123)R
+ *
+ * references:
+ * https://simplebiinsights.com/sql-server-tablesample-retrieving-random-data-from-sql-server/
+ * https://sqlrambling.net/2018/01/24/tablesample-basic-examples/
+ */
+public class TableSample implements ParseNode {
+
+ private final Long sampleValue;
+ private final boolean isPercent;
+ private final Long seek;
+
+ public TableSample(boolean isPercent, Long sampleValue) {
+ this.sampleValue = sampleValue;
+ this.isPercent = isPercent;
+ this.seek = -1L;
+ }
+
+ public TableSample(boolean isPercent, Long sampleValue, Long seek) {
+ this.sampleValue = sampleValue;
+ this.isPercent = isPercent;
+ this.seek = seek;
+ }
+
+ public TableSample(TableSample other) {
+ this.sampleValue = other.sampleValue;
+ this.isPercent = other.isPercent;
+ this.seek = other.seek;
+ }
+
+ public Long getSampleValue() {
+ return sampleValue;
+ }
+
+ public boolean isPercent() {
+ return isPercent;
+ }
+
+ public Long getSeek() {
+ return seek;
+ }
+
+ @Override
+ public void analyze(Analyzer analyzer) throws AnalysisException {
+ if (sampleValue <= 0 || (isPercent && sampleValue > 100)) {
+ throw new AnalysisException("table sample value must be greater than 0, percent need less than 100.");
+ }
+ }
+
+ @Override
+ public String toSql() {
+ if (sampleValue == null) {
+ return "";
+ }
+ StringBuilder sb = new StringBuilder();
+ sb.append("TABLESAMPLE ( ");
+ sb.append(sampleValue);
+ if (isPercent) {
+ sb.append(" PERCENT ");
+ } else {
+ sb.append(" ROWS ");
+ }
+ sb.append(")");
+ if (seek != 0) {
+ sb.append(" REPEATABLE ");
+ sb.append(seek);
Review Comment:
miss parentheses
##########
fe/fe-core/src/main/java/org/apache/doris/analysis/TableRef.java:
##########
@@ -160,6 +161,12 @@ public TableRef(TableName name, String alias, PartitionNames partitionNames, Arr
hasExplicitAlias = false;
}
this.partitionNames = partitionNames;
+ if (sampleTabletIds != null) {
+ this.sampleTabletIds = sampleTabletIds;
+ }
+ if (tableSample != null) {
Review Comment:
i think zhengte is right, even if tableSample is null, it has no side effect.
##########
fe/fe-core/src/main/java/org/apache/doris/analysis/TupleDescriptor.java:
##########
@@ -159,6 +164,80 @@ public void setTable(TableIf tbl) {
table = tbl;
}
+ public Set<Long> getSampleTabletIds() {
+ return sampleTabletIds;
+ }
+
+ /**
+ * First, determine how many rows to sample from each partition according to the number of partitions.
+ * Then determine the number of Tablets to be selected for each partition according to the average number
+ * of rows of Tablet,
+ * If seek is not specified, the specified number of Tablets are pseudo-randomly selected from each partition.
+ * If seek is specified, it will be selected sequentially from the seek tablet of the partition.
+ * And add the manually specified Tablet id to the selected Tablet.
+ * simpleTabletNums = simpleRows / partitionNums / (partitionRows / partitionTabletNums)
+ */
+ public void computeSampleTabletIds(List<Long> tabletIds, TableSample tableSample) {
+ if (table.getType() != TableType.OLAP) {
Review Comment:
i agree, do it during analysis
##########
fe/fe-core/src/main/java/org/apache/doris/analysis/TupleDescriptor.java:
##########
@@ -159,6 +164,84 @@ public void setTable(TableIf tbl) {
table = tbl;
}
+ public Set<Long> getSampleTabletIds() {
+ return sampleTabletIds;
+ }
+
+ /**
+ * First, determine how many rows to sample from each partition according to the number of partitions.
+ * Then determine the number of Tablets to be selected for each partition according to the average number
+ * of rows of Tablet,
+ * If seek is not specified, the specified number of Tablets are pseudo-randomly selected from each partition.
+ * If seek is specified, it will be selected sequentially from the seek tablet of the partition.
+ * And add the manually specified Tablet id to the selected Tablet.
+ * simpleTabletNums = simpleRows / partitionNums / (partitionRows / partitionTabletNums)
+ */
+ public void computeSampleTabletIds(List<Long> tabletIds, TableSample tableSample) {
Review Comment:
why impl this function in TupleDescriptor? since TupleDescriptor is use for describe a tuple, this is very weired.
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