[GitHub] [flink-table-store] JingsongLi commented on a diff in pull request #87: [FLINK-27123] Introduce filter predicate for 'LIKE'

[GitBox <gi...@apache.org>]

JingsongLi commented on code in PR #87:
URL: https://github.com/apache/flink-table-store/pull/87#discussion_r846922818


##########
flink-table-store-core/src/main/java/org/apache/flink/table/store/file/predicate/Like.java:
##########
@@ -0,0 +1,90 @@
+/*
+ * 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.flink.table.store.file.predicate;
+
+import org.apache.flink.table.data.binary.BinaryStringData;
+import org.apache.flink.table.functions.SqlLikeUtils;
+import org.apache.flink.table.store.file.stats.FieldStats;
+
+import javax.annotation.Nullable;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import static org.apache.flink.util.Preconditions.checkNotNull;
+
+/** A {@link Predicate} to evaluate like. */
+public class Like implements Predicate {

Review Comment:
   Maybe we don't need have a like now. We need a better implementation to eval `starts with`. It is similiar to `equals`.
   For example:
   - starts with 'abd'
   - there is a file, min: 'abc' max: 'abe'
   - should return true, because 'abd' is in the file.



##########
flink-table-store-core/src/main/java/org/apache/flink/table/store/file/predicate/Like.java:
##########
@@ -0,0 +1,90 @@
+/*
+ * 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.flink.table.store.file.predicate;
+
+import org.apache.flink.table.data.binary.BinaryStringData;
+import org.apache.flink.table.functions.SqlLikeUtils;
+import org.apache.flink.table.store.file.stats.FieldStats;
+
+import javax.annotation.Nullable;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import static org.apache.flink.util.Preconditions.checkNotNull;
+
+/** A {@link Predicate} to evaluate like. */
+public class Like implements Predicate {
+
+    private static final long serialVersionUID = 1L;
+
+    /** Accepts simple LIKE patterns like "abc%". */
+    private static final Pattern BEGIN_PATTERN = Pattern.compile("([^%_]+)%");
+
+    private final int index;
+
+    private final Literal literal;
+
+    @Nullable private final Literal escapeLiteral;
+
+    public Like(int index, Literal literal, @Nullable Literal escapeLiteral) {
+        this.index = index;
+        this.literal = checkNotNull(literal);
+        this.escapeLiteral = escapeLiteral;
+    }
+
+    @Override
+    public boolean test(Object[] values) {
+        return test(values[index]);
+    }
+
+    @Override
+    public boolean test(long rowCount, FieldStats[] fieldStats) {
+        FieldStats stats = fieldStats[index];
+        if (rowCount == stats.nullCount()) {
+            return false;
+        }
+        return test(stats.minValue()) || test(stats.maxValue());

Review Comment:
   This is wrong, you can see the example in above comment.
   You can add test to cover this.



##########
flink-table-store-core/src/main/java/org/apache/flink/table/store/file/predicate/Like.java:
##########
@@ -0,0 +1,90 @@
+/*
+ * 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.flink.table.store.file.predicate;
+
+import org.apache.flink.table.data.binary.BinaryStringData;
+import org.apache.flink.table.functions.SqlLikeUtils;
+import org.apache.flink.table.store.file.stats.FieldStats;
+
+import javax.annotation.Nullable;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import static org.apache.flink.util.Preconditions.checkNotNull;
+
+/** A {@link Predicate} to evaluate like. */
+public class Like implements Predicate {
+
+    private static final long serialVersionUID = 1L;
+
+    /** Accepts simple LIKE patterns like "abc%". */
+    private static final Pattern BEGIN_PATTERN = Pattern.compile("([^%_]+)%");
+
+    private final int index;
+
+    private final Literal literal;
+
+    @Nullable private final Literal escapeLiteral;
+
+    public Like(int index, Literal literal, @Nullable Literal escapeLiteral) {
+        this.index = index;
+        this.literal = checkNotNull(literal);
+        this.escapeLiteral = escapeLiteral;
+    }
+
+    @Override
+    public boolean test(Object[] values) {
+        return test(values[index]);
+    }
+
+    @Override
+    public boolean test(long rowCount, FieldStats[] fieldStats) {
+        FieldStats stats = fieldStats[index];
+        if (rowCount == stats.nullCount()) {
+            return false;
+        }
+        return test(stats.minValue()) || test(stats.maxValue());
+    }
+
+    private boolean test(Object object) {
+        if (object instanceof BinaryStringData && literal.value() instanceof BinaryStringData) {
+            BinaryStringData field = (BinaryStringData) object;
+            BinaryStringData sqlPattern = (BinaryStringData) literal.value();
+            String sqlPatternStr = sqlPattern.toString();
+            BinaryStringData escape =
+                    escapeLiteral == null ? null : (BinaryStringData) escapeLiteral.value();
+            boolean allowQuick =
+                    escape == null && !sqlPattern.contains(BinaryStringData.fromString("_"));
+            if (allowQuick) {
+                Matcher matcher = BEGIN_PATTERN.matcher(sqlPatternStr);
+                if (matcher.matches()) {
+                    return field.startsWith(BinaryStringData.fromString(matcher.group(1)));
+                }

Review Comment:
   else what? You can add test to cover this.



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