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https://issues.apache.org/jira/browse/DRILL-5899?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16243238#comment-16243238
]
ASF GitHub Bot commented on DRILL-5899:
---------------------------------------
Github user paul-rogers commented on a diff in the pull request:
https://github.com/apache/drill/pull/1015#discussion_r149554195
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/impl/SqlPatternContainsMatcher.java
---
@@ -17,37 +17,48 @@
*/
package org.apache.drill.exec.expr.fn.impl;
-public class SqlPatternContainsMatcher implements SqlPatternMatcher {
- final String patternString;
- CharSequence charSequenceWrapper;
- final int patternLength;
-
- public SqlPatternContainsMatcher(String patternString, CharSequence
charSequenceWrapper) {
- this.patternString = patternString;
- this.charSequenceWrapper = charSequenceWrapper;
- patternLength = patternString.length();
+import io.netty.buffer.DrillBuf;
+
+public class SqlPatternContainsMatcher extends AbstractSqlPatternMatcher {
+
+ public SqlPatternContainsMatcher(String patternString) {
+ super(patternString);
}
@Override
- public int match() {
- final int txtLength = charSequenceWrapper.length();
- int patternIndex = 0;
- int txtIndex = 0;
-
- // simplePattern string has meta characters i.e % and _ and escape
characters removed.
- // so, we can just directly compare.
- while (patternIndex < patternLength && txtIndex < txtLength) {
- if (patternString.charAt(patternIndex) !=
charSequenceWrapper.charAt(txtIndex)) {
- // Go back if there is no match
- txtIndex = txtIndex - patternIndex;
- patternIndex = 0;
- } else {
- patternIndex++;
+ public int match(int start, int end, DrillBuf drillBuf) {
+
+ if (patternLength == 0) { // Everything should match for null pattern
string
+ return 1;
+ }
+
+ final int txtLength = end - start;
+
+ // no match if input string length is less than pattern length
+ if (txtLength < patternLength) {
+ return 0;
+ }
+
+ outer:
+ for (int txtIndex = 0; txtIndex < txtLength; txtIndex++) {
+
+ // boundary check
+ if (txtIndex + patternLength > txtLength) {
--- End diff --
Better:
```
int end = txtLength - patternLength;
for (int txtIndex = 0; txtIndex < end; txtIndex++) {
```
And omit the boundary check on every iteration. That is, no reason to
iterate past the last possible match, then use an if-statement to shorten the
loop. Just shorten the loop.
> Simple pattern matchers can work with DrillBuf directly
> -------------------------------------------------------
>
> Key: DRILL-5899
> URL: https://issues.apache.org/jira/browse/DRILL-5899
> Project: Apache Drill
> Issue Type: Improvement
> Components: Execution - Flow
> Reporter: Padma Penumarthy
> Assignee: Padma Penumarthy
> Priority: Critical
>
> For the 4 simple patterns we have i.e. startsWith, endsWith, contains and
> constant,, we do not need the overhead of charSequenceWrapper. We can work
> with DrillBuf directly. This will save us from doing isAscii check and UTF8
> decoding for each row.
> UTF-8 encoding ensures that no UTF-8 character is a prefix of any other valid
> character. So, instead of decoding varChar from each row we are processing,
> encode the patternString once during setup and do raw byte comparison.
> Instead of bounds checking and reading one byte at a time, we get the whole
> buffer in one shot and use that for comparison.
> This improved overall performance for filter operator by around 20%.
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