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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PHOENIX-4237) Allow sorting on (Java) collation keys for non-English locales
Date Fri, 13 Oct 2017 16:30:00 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-4237?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16203799#comment-16203799
] 

ASF GitHub Bot commented on PHOENIX-4237:
-----------------------------------------

Github user JamesRTaylor commented on a diff in the pull request:

    https://github.com/apache/phoenix/pull/275#discussion_r144600094
  
    --- Diff: phoenix-core/src/main/java/org/apache/phoenix/expression/function/CollationKeyFunction.java
---
    @@ -0,0 +1,233 @@
    +package org.apache.phoenix.expression.function;
    +
    +import java.sql.SQLException;
    +import java.text.Collator;
    +import java.util.Arrays;
    +import java.util.List;
    +import java.util.Locale;
    +
    +import org.apache.commons.lang.BooleanUtils;
    +import org.apache.commons.logging.Log;
    +import org.apache.commons.logging.LogFactory;
    +import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
    +import org.apache.phoenix.expression.Expression;
    +import org.apache.phoenix.parse.FunctionParseNode;
    +import org.apache.phoenix.schema.tuple.Tuple;
    +import org.apache.phoenix.schema.types.PBoolean;
    +import org.apache.phoenix.schema.types.PDataType;
    +import org.apache.phoenix.schema.types.PInteger;
    +import org.apache.phoenix.schema.types.PIntegerArray;
    +import org.apache.phoenix.schema.types.PUnsignedIntArray;
    +import org.apache.phoenix.schema.types.PVarbinary;
    +import org.apache.phoenix.schema.types.PVarchar;
    +import org.apache.phoenix.schema.types.PhoenixArray;
    +
    +import com.force.db.i18n.LinguisticSort;
    +import com.force.i18n.LocaleUtils;
    +
    +import com.ibm.icu.impl.jdkadapter.CollatorICU;
    +import com.ibm.icu.util.ULocale;
    +
    +/**
    + * A Phoenix Function that calculates a collation key for an input string based
    + * on a caller-provided locale and collator strength and decomposition settings.
    + * 
    + * It uses the open-source grammaticus and i18n packages to obtain the collators
    + * it needs.
    + * 
    + * @author snakhoda
    + *
    + */
    +@FunctionParseNode.BuiltInFunction(name = CollationKeyFunction.NAME, args = {
    +		// input string
    +		@FunctionParseNode.Argument(allowedTypes = { PVarchar.class }),
    +		// ISO Code for Locale
    +		@FunctionParseNode.Argument(allowedTypes = { PVarchar.class }, isConstant = true),
    +		// whether to use special upper case collator
    +		@FunctionParseNode.Argument(allowedTypes = { PBoolean.class }, defaultValue = "false",
isConstant = true),
    +		// collator strength
    +		@FunctionParseNode.Argument(allowedTypes = { PInteger.class }, defaultValue = "null",
isConstant = true),
    +		// collator decomposition
    +		@FunctionParseNode.Argument(allowedTypes = { PInteger.class }, defaultValue = "null",
isConstant = true) })
    +public class CollationKeyFunction extends ScalarFunction {
    +
    +	private static final Log LOG = LogFactory.getLog(CollationKeyFunction.class);
    +
    +	public static final String NAME = "COLLKEY";
    +
    +	public CollationKeyFunction() {
    +	}
    +
    +	public CollationKeyFunction(List<Expression> children) throws SQLException {
    +		super(children);
    +	}
    +
    +	@Override
    +	public boolean evaluate(Tuple tuple, ImmutableBytesWritable ptr) {
    +		try {
    +			String inputValue = getInputValue(tuple, ptr);
    +			String localeISOCode = getLocaleISOCode(tuple, ptr);
    +			Boolean useSpecialUpperCaseCollator = getUseSpecialUpperCaseCollator(tuple, ptr);
    +			Integer collatorStrength = getCollatorStrength(tuple, ptr);
    +			Integer collatorDecomposition = getCollatorDecomposition(tuple, ptr);
    +
    +			Locale locale = LocaleUtils.get().getLocaleByIsoCode(localeISOCode);
    +			
    +			if(LOG.isDebugEnabled()) {
    +				LOG.debug(String.format("Locale: " + locale.toLanguageTag()));
    +			}
    +			
    +			LinguisticSort linguisticSort = LinguisticSort.get(locale);
    +
    +			Collator collator = BooleanUtils.isTrue(useSpecialUpperCaseCollator)
    +					? linguisticSort.getUpperCaseCollator(false) : linguisticSort.getCollator();
    +
    +			if (collatorStrength != null) {
    +				collator.setStrength(collatorStrength);
    +			}
    +
    +			if (collatorDecomposition != null) {
    +				collator.setDecomposition(collatorDecomposition);
    +			}
    +
    +			if(LOG.isDebugEnabled()) {
    +				LOG.debug(String.format("Collator: [strength: %d, decomposition: %d], Special-Upper-Case:
%s",
    +					collator.getStrength(), collator.getDecomposition(), BooleanUtils.isTrue(useSpecialUpperCaseCollator)));
    +			}
    +			
    +			byte[] collationKeyByteArray = collator.getCollationKey(inputValue).toByteArray();
    +
    +			if(LOG.isDebugEnabled()) {
    +				LOG.debug("Collation key bytes:" + Arrays.toString(collationKeyByteArray));
    +			}
    +			
    +			// byte is signed in Java, but we need unsigned values for comparison
    +			// https://www.programcreek.com/java-api-examples/index.php?api=java.text.CollationKey
    +			// Byte.toUnsignedInt will convert a byte value between [-128,127] to an int value
    +			// between [0,255]
    --- End diff --
    
    > doing a Java comparison on them with regular operators (which is presumably what
Phoenix does) produces incorrect results
    
    That's not what Phoenix does. That's what I tried to explain in my previous comment. In
your unit tests, the best way to confirm this is through an end-to-end integration test that
uses an ORDER BY COLLKEY(my_varchar_col):
    * Create a simple table CREATE TABLE t (k INTEGER PRIMARY KEY, v VARCHAR)
    * Populate the table with some multi-byte string values:
        UPSERT INTO t VALUES(1,'ണഫɰɸ')
        UPSERT INTO t VALUES(2,'ɚɦ')
    * Execute an ORDER BY on the table: SELECT * FROM t ORDER BY COLLKEY(v)
    * Confirm that the rows are ordered as expected by a linguistic sort
    
    The above test is a must-have. We can also have lower level unit tests that don't need
to run as an integration test to test the sorting. You'd need to manually create an OrderedResultIterator.
See OrderedResultIteratorTest as an example.


> Allow sorting on (Java) collation keys for non-English locales
> --------------------------------------------------------------
>
>                 Key: PHOENIX-4237
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-4237
>             Project: Phoenix
>          Issue Type: Improvement
>            Reporter: Shehzaad Nakhoda
>             Fix For: 4.12.0
>
>
> Strings stored via Phoenix can be composed from a subset of the entire set of Unicode
characters. The natural sort order for strings for different languages often differs from
the order dictated by the binary representation of the characters of these strings. Java provides
the idea of a Collator which given an input string and a (language) locale can generate a
Collation Key which can then be used to compare strings in that natural order.
> Salesforce has recently open-sourced grammaticus. IBM has open-sourced ICU4J some time
ago. These technologies can be combined to provide a robust new Phoenix function that can
be used in an ORDER BY clause to sort strings according to the user's locale.



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