Add ST_EXTENT aggregate function

h2/src/docsrc/help/help.csv

@@ -3437,6 +3437,18 @@ MODE(X ORDER BY X)
 MODE() WITHIN GROUP(ORDER BY X)
 "
 
+"Functions (Aggregate)","ST_EXTENT","
+{ ST_EXTENT( value ) [ FILTER ( WHERE expression ) ]
+","
+Returns the minimum bounding box that encloses all specified GEOMETRY values.
+Only 2D coordinate plane is supported.
+NULL values are ignored in the calculation.
+If no rows are selected, the result is NULL.
+Aggregates are only allowed in select statements.
+","
+ST_EXTENT(X)
+"
+
 "Functions (Numeric)","ABS","
 ABS ( { numeric } )
 ","

h2/src/main/org/h2/expression/aggregate/Aggregate.java

@@ -142,6 +142,11 @@ public class Aggregate extends Expression {
          * The aggregate type for MODE(expression).
          */
         MODE,
+
+        /**
+         * The aggregate type for ST_EXTENT(expression).
+         */
+        ST_EXTENT,
     }
 
     private static final HashMap<String, AggregateType> AGGREGATES = new HashMap<>(64);
@@ -212,6 +217,7 @@ public class Aggregate extends Expression {
         addAggregate("MODE", AggregateType.MODE);
         // Oracle compatibility
         addAggregate("STATS_MODE", AggregateType.MODE);
+        addAggregate("ST_EXTENT", AggregateType.ST_EXTENT);
     }
 
     private static void addAggregate(String name, AggregateType type) {
@@ -369,9 +375,10 @@ public class Aggregate extends Expression {
                 }
                 return v;
             }
-            case MEDIAN: {
+            case MEDIAN:
                 return AggregateDataMedian.getResultFromIndex(session, on, dataType);
-            }
+            case ST_EXTENT:
+                return AggregateDataST_Extent.getResultFromIndex(session, on);
             default:
                 DbException.throwInternalError("type=" + type);
             }
@@ -554,6 +561,11 @@ public class Aggregate extends Expression {
             scale = 0;
             precision = displaySize = Integer.MAX_VALUE;
             break;
+        case ST_EXTENT:
+            dataType = Value.GEOMETRY;
+            scale = 0;
+            precision = displaySize = Integer.MAX_VALUE;
+            break;
         default:
             DbException.throwInternalError("type=" + type);
         }
@@ -699,6 +711,9 @@ public class Aggregate extends Expression {
         case MODE:
             text = "MODE";
             break;
+        case ST_EXTENT:
+            text = "ST_EXTENT";
+            break;
         default:
             throw DbException.throwInternalError("type=" + type);
         }
@@ -749,6 +764,8 @@ public class Aggregate extends Expression {
                     return false;
                 }
                 return AggregateDataMedian.getMedianColumnIndex(on) != null;
+            case ST_EXTENT:
+                return AggregateDataST_Extent.getGeometryColumnIndex(on) != null;
             default:
                 return false;
             }

h2/src/main/org/h2/expression/aggregate/AggregateData.java

@@ -37,6 +37,8 @@ abstract class AggregateData {
             return new AggregateDataMedian();
         case MODE:
             return new AggregateDataMode();
+        case ST_EXTENT:
+            return new AggregateDataST_Extent();
         default:
             return new AggregateDataDefault(aggregateType);
         }

h2/src/main/org/h2/expression/aggregate/AggregateDataST_Extent.java

+/*
+ * Copyright 2004-2018 H2 Group. Multiple-Licensed under the MPL 2.0,
+ * and the EPL 1.0 (http://h2database.com/html/license.html).
+ * Initial Developer: H2 Group
+ */
+package org.h2.expression.aggregate;
+
+import java.util.ArrayList;
+
+import org.h2.engine.Database;
+import org.h2.engine.Session;
+import org.h2.expression.Expression;
+import org.h2.expression.ExpressionColumn;
+import org.h2.index.Index;
+import org.h2.mvstore.db.MVSpatialIndex;
+import org.h2.mvstore.rtree.SpatialKey;
+import org.h2.table.Column;
+import org.h2.table.TableFilter;
+import org.h2.value.Value;
+import org.h2.value.ValueGeometry;
+import org.h2.value.ValueNull;
+import org.locationtech.jts.geom.Envelope;
+import org.locationtech.jts.geom.GeometryFactory;
+
+/**
+ * Data stored while calculating an aggregate.
+ */
+class AggregateDataST_Extent extends AggregateData {
+
+    private Envelope envelope;
+
+    /**
+     * Get the index (if any) for the column specified in the geometry
+     * aggregate.
+     *
+     * @param on
+     *            the expression (usually a column expression)
+     * @return the index, or null
+     */
+    static Index getGeometryColumnIndex(Expression on) {
+        if (on instanceof ExpressionColumn) {
+            ExpressionColumn col = (ExpressionColumn) on;
+            Column column = col.getColumn();
+            if (column.getType() == Value.GEOMETRY) {
+                TableFilter filter = col.getTableFilter();
+                if (filter != null) {
+                    ArrayList<Index> indexes = filter.getTable().getIndexes();
+                    if (indexes != null) {
+                        for (int i = 1, size = indexes.size(); i < size; i++) {
+                            Index index = indexes.get(i);
+                            if (index instanceof MVSpatialIndex) {
+                                return index;
+                            }
+                        }
+                    }
+                }
+            }
+        }
+        return null;
+    }
+
+    /**
+     * Get the result from the index.
+     *
+     * @param session
+     *            the session
+     * @param on
+     *            the expression
+     * @return the result
+     */
+    static Value getResultFromIndex(Session session, Expression on) {
+        MVSpatialIndex index = (MVSpatialIndex) getGeometryColumnIndex(on);
+        MVSpatialIndex.MVStoreCursor cursor = (MVSpatialIndex.MVStoreCursor) index.find(session, null, null);
+        Envelope envelope = new Envelope();
+        while (cursor.next()) {
+            SpatialKey key = cursor.getKey();
+            if (!key.isNull()) {
+                envelope.expandToInclude(key.min(0), key.min(1));
+                envelope.expandToInclude(key.max(0), key.max(1));
+            }
+        }
+        if (envelope.isNull()) {
+            return ValueNull.INSTANCE;
+        }
+        return ValueGeometry.getFromGeometry(new GeometryFactory().toGeometry(envelope));
+    }
+
+    @Override
+    void add(Database database, int dataType, boolean distinct, Value v) {
+        if (v == ValueNull.INSTANCE) {
+            return;
+        }
+        if (envelope == null) {
+            envelope = new Envelope();
+        }
+        envelope.expandToInclude(((ValueGeometry) v.convertTo(Value.GEOMETRY)).getEnvelopeNoCopy());
+    }
+
+    @Override
+    Value getValue(Database database, int dataType, boolean distinct) {
+        if (envelope == null || envelope.isNull()) {
+            return ValueNull.INSTANCE;
+        }
+        return ValueGeometry.getFromGeometry(new GeometryFactory().toGeometry(envelope));
+    }
+
+}

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

@@ -321,7 +321,7 @@ public class MVSpatialIndex extends BaseIndex implements SpatialIndex, MVIndex {
     /**
      * A cursor.
      */
-    private static class MVStoreCursor implements Cursor {
+    public static class MVStoreCursor implements Cursor {
 
         private final Session session;
         private final Iterator<SpatialKey> it;
@@ -358,6 +358,15 @@ public class MVSpatialIndex extends BaseIndex implements SpatialIndex, MVIndex {
             return searchRow;
         }
 
+        /**
+         * Returns the current key.
+         *
+         * @return the current key
+         */
+        public SpatialKey getKey() {
+            return current;
+        }
+
         @Override
         public boolean next() {
             current = it.hasNext() ? it.next() : null;

h2/src/test/org/h2/test/scripts/TestScript.java

@@ -137,7 +137,7 @@ public class TestScript extends TestDb {
             testScript("other/" + s + ".sql");
         }
         for (String s : new String[] { "avg", "bit-and", "bit-or", "count",
-                "group-concat", "max", "median", "min", "mode", "selectivity", "stddev-pop",
+                "group-concat", "max", "median", "min", "mode", "selectivity", "st_extent", "stddev-pop",
                 "stddev-samp", "sum", "var-pop", "var-samp", "array-agg" }) {
             testScript("functions/aggregate/" + s + ".sql");
         }

h2/src/test/org/h2/test/scripts/functions/aggregate/st_extent.sql

+-- Copyright 2004-2018 H2 Group. Multiple-Licensed under the MPL 2.0,
+-- and the EPL 1.0 (http://h2database.com/html/license.html).
+-- Initial Developer: H2 Group
+--
+
+CREATE TABLE TEST(V GEOMETRY);
+> ok
+
+SELECT ST_EXTENT(V) FROM TEST;
+>> null
+
+INSERT INTO TEST VALUES ('POINT(1 1)');
+> update count: 1
+
+SELECT ST_EXTENT(V) FROM TEST;
+>> POINT (1 1)
+
+INSERT INTO TEST VALUES ('POINT(1 2)'), (NULL), ('POINT(3 1)');
+> update count: 3
+
+SELECT ST_EXTENT(V), ST_EXTENT(V) FILTER (WHERE V <> 'POINT(3 1)') FILTERED1,
+    ST_EXTENT(V) FILTER (WHERE V <> 'POINT(1 2)') FILTERED2 FROM TEST;
+> ST_EXTENT(V)                        FILTERED1             FILTERED2
+> ----------------------------------- --------------------- ---------------------
+> POLYGON ((1 1, 1 2, 3 2, 3 1, 1 1)) LINESTRING (1 1, 1 2) LINESTRING (1 1, 3 1)
+> rows: 1
+
+CREATE SPATIAL INDEX IDX ON TEST(V);
+> ok
+
+-- With index
+SELECT ST_EXTENT(V) FROM TEST;
+>> POLYGON ((1 1, 1 2, 3 2, 3 1, 1 1))
+
+SELECT ST_EXTENT(V) FILTER (WHERE V <> 'POINT(3 1)') FILTERED FROM TEST;
+>> LINESTRING (1 1, 1 2)
+
+SELECT ST_EXTENT(V) FROM TEST WHERE V <> 'POINT(3 1)';
+>> LINESTRING (1 1, 1 2)
+
+TRUNCATE TABLE TEST;
+> ok
+
+-- With index
+SELECT ST_EXTENT(V) FROM TEST;
+>> null
+
+DROP TABLE TEST;
+> ok