Rename containsNullAndAllowMultipleNull() to mayHaveDuplicates()

Previous name was incorrect.

h2/src/main/org/h2/engine/Mode.java

@@ -87,17 +87,16 @@ public class Mode {
     public boolean systemColumns;
 
     /**
-     * For unique indexes, NULL is distinct. That means only one row with NULL
-     * in one of the columns is allowed.
+     * <ul>
+     * <li>If {@code 0}, multiple identical indexed columns with at least one
+     * {@code NULL} value are allowed in unique index.</li>
+     * <li>If {@code 1}, multiple identical indexed columns with all {@code NULL}
+     * values are allowed in unique index.</li>
+     * <li>If {@code 2}, multiple identical indexed columns are not allowed in
+     * unique index.</li>
+     * </ul>
      */
-    public boolean uniqueIndexSingleNull;
-
-    /**
-     * When using unique indexes, multiple rows with NULL in all columns
-     * are allowed, however it is not allowed to have multiple rows with the
-     * same values otherwise.
-     */
-    public boolean uniqueIndexSingleNullExceptAllColumnsAreNull;
+    public byte uniquieIndexNullsHandling;
 
     /**
      * Empty strings are treated like NULL values. Useful for Oracle emulation.
@@ -208,7 +207,7 @@ public class Mode {
 
         mode = new Mode(ModeEnum.Derby.name());
         mode.aliasColumnName = true;
-        mode.uniqueIndexSingleNull = true;
+        mode.uniquieIndexNullsHandling = 2;
         mode.supportOffsetFetch = true;
         mode.sysDummy1 = true;
         mode.isolationLevelInSelectOrInsertStatement = true;
@@ -220,7 +219,7 @@ public class Mode {
         mode.aliasColumnName = true;
         mode.convertOnlyToSmallerScale = true;
         mode.nullConcatIsNull = true;
-        mode.uniqueIndexSingleNull = true;
+        mode.uniquieIndexNullsHandling = 2;
         mode.allowPlusForStringConcat = true;
         // HSQLDB does not support client info properties. See
         // http://hsqldb.org/doc/apidocs/
@@ -232,7 +231,7 @@ public class Mode {
         mode = new Mode(ModeEnum.MSSQLServer.name());
         mode.aliasColumnName = true;
         mode.squareBracketQuotedNames = true;
-        mode.uniqueIndexSingleNull = true;
+        mode.uniquieIndexNullsHandling = 2;
         mode.allowPlusForStringConcat = true;
         mode.swapConvertFunctionParameters = true;
         mode.supportPoundSymbolForColumnNames = true;
@@ -260,7 +259,7 @@ public class Mode {
         mode = new Mode(ModeEnum.Oracle.name());
         mode.aliasColumnName = true;
         mode.convertOnlyToSmallerScale = true;
-        mode.uniqueIndexSingleNullExceptAllColumnsAreNull = true;
+        mode.uniquieIndexNullsHandling = 1;
         mode.treatEmptyStringsAsNull = true;
         mode.regexpReplaceBackslashReferences = true;
         mode.supportPoundSymbolForColumnNames = true;

h2/src/main/org/h2/index/BaseIndex.java

@@ -9,7 +9,6 @@ import java.util.HashSet;
 import org.h2.api.ErrorCode;
 import org.h2.engine.Constants;
 import org.h2.engine.DbObject;
-import org.h2.engine.Mode;
 import org.h2.engine.Session;
 import org.h2.message.DbException;
 import org.h2.message.Trace;
@@ -302,33 +301,43 @@ public abstract class BaseIndex extends SchemaObjectBase implements Index {
     }
 
     /**
-     * Check if one of the columns is NULL and multiple rows with NULL are
-     * allowed using the current compatibility mode for unique indexes. Note:
-     * NULL behavior is complicated in SQL.
+     * Check if this row may have duplicates with the same indexed values in the
+     * current compatibility mode.
      *
-     * @param newRow the row to check
-     * @return true if one of the columns is null and multiple nulls in unique
-     *         indexes are allowed
+     * @param searchRow
+     *            the row to check
+     * @return {@code true} if specified row may have duplicates,
+     *         {@code false otherwise}
      */
-    protected boolean containsNullAndAllowMultipleNull(SearchRow newRow) {
-        Mode mode = database.getMode();
-        if (mode.uniqueIndexSingleNull) {
+    protected boolean mayHaveDuplicates(SearchRow searchRow) {
+        int mode = database.getMode().uniquieIndexNullsHandling;
+        /*
+         * Multiple identical indexed columns with at least one NULL value are allowed
+         * in unique index.
+         */
+        if (mode == 0) {
+            for (int index : columnIds) {
+                if (searchRow.getValue(index) == ValueNull.INSTANCE) {
+                    return true;
+                }
+            }
             return false;
-        } else if (mode.uniqueIndexSingleNullExceptAllColumnsAreNull) {
+        }
+        /*
+         * Multiple identical indexed columns with all {@code NULL} values are allowed
+         * in unique index.
+         */
+        if (mode == 1) {
             for (int index : columnIds) {
-                Value v = newRow.getValue(index);
-                if (v != ValueNull.INSTANCE) {
+                if (searchRow.getValue(index) != ValueNull.INSTANCE) {
                     return false;
                 }
             }
             return true;
         }
-        for (int index : columnIds) {
-            Value v = newRow.getValue(index);
-            if (v == ValueNull.INSTANCE) {
-                return true;
-            }
-        }
+        /*
+         * Multiple identical indexed columns are not allowed in unique index.
+         */
         return false;
     }
 

h2/src/main/org/h2/index/PageBtree.java

@@ -116,7 +116,7 @@ public abstract class PageBtree extends Page {
             comp = index.compareRows(row, compare);
             if (comp == 0) {
                 if (add && index.indexType.isUnique()) {
-                    if (!index.containsNullAndAllowMultipleNull(compare)) {
+                    if (!index.mayHaveDuplicates(compare)) {
                         throw index.getDuplicateKeyException(compare.toString());
                     }
                 }

h2/src/main/org/h2/index/TreeIndex.java

@@ -66,7 +66,7 @@ public class TreeIndex extends BaseIndex {
             int compare = compareRows(row, r);
             if (compare == 0) {
                 if (indexType.isUnique()) {
-                    if (!containsNullAndAllowMultipleNull(row)) {
+                    if (!mayHaveDuplicates(row)) {
                         throw getDuplicateKeyException(row.toString());
                     }
                 }

h2/src/main/org/h2/mvstore/db/MVSecondaryIndex.java

@@ -208,7 +208,7 @@ public final class MVSecondaryIndex extends BaseIndex implements MVIndex {
                 if (compareRows(row, r2) != 0) {
                     break;
                 }
-                if (containsNullAndAllowMultipleNull(r2)) {
+                if (mayHaveDuplicates(r2)) {
                     // this is allowed
                     continue;
                 }
@@ -233,7 +233,7 @@ public final class MVSecondaryIndex extends BaseIndex implements MVIndex {
                 break;
             }
             if (map.get(k) != null) {
-                if (!containsNullAndAllowMultipleNull(r2)) {
+                if (!mayHaveDuplicates(r2)) {
                     throw getDuplicateKeyException(k.toString());
                 }
             }