From 1ceddf40c0e5f049213fff00caba683d630c5033 Mon Sep 17 00:00:00 2001
From: Donnie Pinkston <donnie@cms.caltech.edu>
Date: Wed, 30 Jan 2019 14:44:36 -0800
Subject: [PATCH] Aggregate function bugfixes
A number of bugfixes caused by some of the changes in the arithmetic
type-coercion rules, and the parser-framework changes.
COUNT(DISTINCT a) wasn't being handled correctly due to an issue in
the NanoSQLTranslator flow-control.
The SumAvg/StdDevVar aggregate implementations are now updated to
produce double-precision results when calculating their values. The
type-converter had been changed to do integer division when the LHS
and RHS are both integers, and this was breaking tests of these
aggregate functions.
---
.../nanodb/functions/StdDevVarAggregate.java | 30 +++++++++----------
.../nanodb/functions/SumAvgAggregate.java | 3 +-
.../nanodb/sqlparse/NanoSQLTranslator.java | 6 ++--
3 files changed, 20 insertions(+), 19 deletions(-)
diff --git a/src/main/java/edu/caltech/nanodb/functions/StdDevVarAggregate.java b/src/main/java/edu/caltech/nanodb/functions/StdDevVarAggregate.java
index 1f8142c..1b9efe5 100755
--- a/src/main/java/edu/caltech/nanodb/functions/StdDevVarAggregate.java
+++ b/src/main/java/edu/caltech/nanodb/functions/StdDevVarAggregate.java
@@ -49,7 +49,7 @@ public class StdDevVarAggregate extends AggregateFunction {
// Store the new value
values.add(value);
}
-
+
if (sum == null) {
// This is the first value. Store it.
sum = value;
@@ -61,17 +61,18 @@ public class StdDevVarAggregate extends AggregateFunction {
}
}
-
+
@Override
public Object getResult() {
if (sum == null || values == null)
return null;
else {
- int count = values.size();
+ // TODO: Need to generate NUMERIC result. Using double right now.
+ double count = (double) values.size();
// Compute average from the sum and count.
Object avg = ArithmeticOperator.evalObjects(
- ArithmeticOperator.Type.DIVIDE, sum, Integer.valueOf(count));
-
+ ArithmeticOperator.Type.DIVIDE, sum, count);
+
// Compute the sum of the square of the residuals.
Object sumSquaresResids = squareDifference(values.get(0), avg);
for (int i = 1; i < count; i++) {
@@ -79,12 +80,11 @@ public class StdDevVarAggregate extends AggregateFunction {
ArithmeticOperator.Type.ADD, sumSquaresResids,
squareDifference(values.get(i), avg));
}
-
+
// Compute the variance.
Object var = ArithmeticOperator.evalObjects(
- ArithmeticOperator.Type.DIVIDE, sumSquaresResids,
- Integer.valueOf(count));
-
+ ArithmeticOperator.Type.DIVIDE, sumSquaresResids, count);
+
// Compute standard deviation if necessary.
if (computeStdDev) {
return ArithmeticOperator.evalObjects(
@@ -95,8 +95,8 @@ public class StdDevVarAggregate extends AggregateFunction {
}
}
}
-
-
+
+
@Override
public ColumnType getReturnType(List<Expression> args, Schema schema) {
if (args.size() != 1) {
@@ -109,11 +109,11 @@ public class StdDevVarAggregate extends AggregateFunction {
// same type as the values of the column.
return args.get(0).getColumnInfo(schema).getType();
}
-
-
- /**
+
+
+ /**
* Helper function that computes the square of the difference between
- * two values.
+ * two values.
*/
private Object squareDifference(Object value, Object avg) {
return ArithmeticOperator.evalObjects(ArithmeticOperator.Type.POWER,
diff --git a/src/main/java/edu/caltech/nanodb/functions/SumAvgAggregate.java b/src/main/java/edu/caltech/nanodb/functions/SumAvgAggregate.java
index 5d09a91..d7bfe18 100644
--- a/src/main/java/edu/caltech/nanodb/functions/SumAvgAggregate.java
+++ b/src/main/java/edu/caltech/nanodb/functions/SumAvgAggregate.java
@@ -91,9 +91,10 @@ public class SumAvgAggregate extends AggregateFunction {
return null;
}
else if (computeAverage) {
+ // TODO: Need to generate NUMERIC result. Using double right now.
// Compute average from the sum and count.
return ArithmeticOperator.evalObjects(
- ArithmeticOperator.Type.DIVIDE, sum, Integer.valueOf(count));
+ ArithmeticOperator.Type.DIVIDE, sum, (double) count);
}
else {
// Just return the sum.
diff --git a/src/main/java/edu/caltech/nanodb/sqlparse/NanoSQLTranslator.java b/src/main/java/edu/caltech/nanodb/sqlparse/NanoSQLTranslator.java
index d213621..3a7f236 100644
--- a/src/main/java/edu/caltech/nanodb/sqlparse/NanoSQLTranslator.java
+++ b/src/main/java/edu/caltech/nanodb/sqlparse/NanoSQLTranslator.java
@@ -882,11 +882,11 @@ public class NanoSQLTranslator extends NanoSQLBaseVisitor<Object> {
ColumnName colName = ((ColumnValue) e).getColumnName();
if (colName.isColumnWildcard())
functionName += "#STAR";
+ else if (distinct)
+ functionName += "#DISTINCT";
}
}
- else if (distinct) {
- functionName += "#DISTINCT";
- }
+ // TODO: Report error if someone uses DISTINCT with multiple args.
FunctionCall fnCall = new FunctionCall(functionName, distinct, args);
if (functionDirectory != null)
--
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