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https://issues.apache.org/jira/browse/DRILL-8094?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17477296#comment-17477296
]
ASF GitHub Bot commented on DRILL-8094:
---------------------------------------
jnturton commented on a change in pull request #2416:
URL: https://github.com/apache/drill/pull/2416#discussion_r776967381
##########
File path:
exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/impl/StringFunctions.java
##########
@@ -416,16 +417,25 @@ public void setup() {
@Override
public void eval() {
- if (index.value < 1) {
+ if (index.value == 0) {
throw org.apache.drill.common.exceptions.UserException.functionError()
- .message("Index in split_part must be positive, value provided was "
- + index.value).build();
+ .message("Index in split_part can not be zero").build();
}
String inputString = org.apache.drill.exec.expr.fn.impl.
StringFunctionHelpers.getStringFromVarCharHolder(in);
- int arrayIndex = index.value - 1;
- String result =
- (String)
com.google.common.collect.Iterables.get(splitter.split(inputString),
arrayIndex, "");
+ String result = "";
+ if (index.value < 0) {
+ java.util.List<String> splits = splitter.splitToList(inputString);
+ int size = splits.size();
+ int arrayIndex = size + index.value;
+ if (arrayIndex >= 0) {
Review comment:
For performance we try to avoid branching inside function `eval` methods
whenever possible. Can any of these `if` statements be removed? E.g. by using
modular arithmetic to calculate the wrapped array index.
##########
File path:
exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/impl/StringFunctions.java
##########
@@ -416,16 +417,25 @@ public void setup() {
@Override
public void eval() {
- if (index.value < 1) {
+ if (index.value == 0) {
throw org.apache.drill.common.exceptions.UserException.functionError()
- .message("Index in split_part must be positive, value provided was "
- + index.value).build();
+ .message("Index in split_part can not be zero").build();
}
String inputString = org.apache.drill.exec.expr.fn.impl.
StringFunctionHelpers.getStringFromVarCharHolder(in);
- int arrayIndex = index.value - 1;
- String result =
- (String)
com.google.common.collect.Iterables.get(splitter.split(inputString),
arrayIndex, "");
+ String result = "";
+ if (index.value < 0) {
+ java.util.List<String> splits = splitter.splitToList(inputString);
+ int size = splits.size();
+ int arrayIndex = size + index.value;
+ if (arrayIndex >= 0) {
Review comment:
Okay that does actually appear to be consistent with what happens when
arrayIndex is past the end of the array.
##########
File path:
exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/impl/StringFunctions.java
##########
@@ -416,16 +417,25 @@ public void setup() {
@Override
public void eval() {
- if (index.value < 1) {
+ if (index.value == 0) {
throw org.apache.drill.common.exceptions.UserException.functionError()
- .message("Index in split_part must be positive, value provided was "
- + index.value).build();
+ .message("Index in split_part can not be zero").build();
}
String inputString = org.apache.drill.exec.expr.fn.impl.
StringFunctionHelpers.getStringFromVarCharHolder(in);
- int arrayIndex = index.value - 1;
- String result =
- (String)
com.google.common.collect.Iterables.get(splitter.split(inputString),
arrayIndex, "");
+ String result = "";
+ if (index.value < 0) {
+ java.util.List<String> splits = splitter.splitToList(inputString);
+ int size = splits.size();
+ int arrayIndex = size + index.value;
+ if (arrayIndex >= 0) {
Review comment:
Perhaps in the context of this sort of string processing, branching
penalities are not very significant 🤔
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> Support reverse truncation for split_part udf
> ---------------------------------------------
>
> Key: DRILL-8094
> URL: https://issues.apache.org/jira/browse/DRILL-8094
> Project: Apache Drill
> Issue Type: Improvement
> Reporter: wtf
> Priority: Minor
>
> suport split_part('a,b,c,d', ',' , -2, -1) = 'c,d' and split_part('a,b,c,d',
> ',' , -3) = 'b'
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