Add a DISK_SPACE_USED system function. Fixes issue 270.

h2/src/docsrc/help/help.csv

@@ -3573,6 +3573,16 @@ This function is provided for Oracle compatibility (see there for details).
 CALL DECODE(RAND()>0.5, 0, 'Red', 1, 'Black');
 "
 
+"Functions (System)","DISK_SPACE_USED","
+DISK_SPACE_USED(tablename)
+","
+Returns the approximate amount of space used by the table specified.
+Does not currently take into account indexes or LOB's.
+This function may be expensive since it has to load every page in the table.
+","
+CALL DISK_SPACE_USED('my_table');
+"
+
 "Functions (System)","FILE_READ","
 FILE_READ(fileNameString [,encodingString])
 ","

h2/src/docsrc/html/changelog.html

@@ -36,6 +36,7 @@ Change Log
 </ul><li>Support ALTER TABLE ADD ... AFTER. Patch from Andrew Gaul (argaul at gmail.com). Fixes issue 401.
 </ul><li>support "SELECT version()". Patch from Andrew Gaul. Fixes issue 406.
 </ul><li>Improved OSGi support. H2 now registers itself as a DataSourceFactory service. Fixes issue 365.
+</ul><li>Add a DISK_SPACE_USED system function. Fixes issue 270.
 </li></ul>
 
 <h2>Version 1.3.170 (2012-11-30)</h2>

h2/src/main/org/h2/command/Parser.java

@@ -5379,4 +5379,16 @@ public class Parser {
         return readExpression();
     }
 
+    /**
+     * Parse a SQL code snippet that represents a table name.
+     *
+     * @param sql the code snippet
+     * @return the table object
+     */
+    public Table parseTableName(String sql) {
+        parameters = New.arrayList();
+        initialize(sql);
+        read();
+        return readTableOrView();
+    }
 }

h2/src/main/org/h2/expression/Function.java

@@ -40,6 +40,7 @@ import org.h2.store.fs.FileUtils;
 import org.h2.table.Column;
 import org.h2.table.ColumnResolver;
 import org.h2.table.LinkSchema;
+import org.h2.table.Table;
 import org.h2.table.TableFilter;
 import org.h2.tools.CompressTool;
 import org.h2.tools.Csv;
@@ -92,7 +93,7 @@ public class Function extends Expression implements FunctionCall {
             ISO_YEAR = 123, ISO_WEEK = 124, ISO_DAY_OF_WEEK = 125;
 
     public static final int DATABASE = 150, USER = 151, CURRENT_USER = 152, IDENTITY = 153, SCOPE_IDENTITY = 154,
-            AUTOCOMMIT = 155, READONLY = 156, DATABASE_PATH = 157, LOCK_TIMEOUT = 158;
+            AUTOCOMMIT = 155, READONLY = 156, DATABASE_PATH = 157, LOCK_TIMEOUT = 158, DISK_SPACE_USED = 159;
 
     public static final int IFNULL = 200, CASEWHEN = 201, CONVERT = 202, CAST = 203, COALESCE = 204, NULLIF = 205,
             CASE = 206, NEXTVAL = 207, CURRVAL = 208, ARRAY_GET = 209, CSVREAD = 210, CSVWRITE = 211,
@@ -346,6 +347,7 @@ public class Function extends Expression implements FunctionCall {
         addFunctionNotDeterministic("TRANSACTION_ID", TRANSACTION_ID, 0, Value.STRING);
         addFunctionWithNull("DECODE", DECODE, VAR_ARGS, Value.NULL);
         addFunction("VERSION", VERSION, 0, Value.STRING);
+        addFunctionNotDeterministic("DISK_SPACE_USED", DISK_SPACE_USED, 1, Value.LONG);
 
         // TableFunction
         addFunctionWithNull("TABLE", TABLE, VAR_ARGS, Value.RESULT_SET);
@@ -760,6 +762,9 @@ public class Function extends Expression implements FunctionCall {
         case LOCK_TIMEOUT:
             result = ValueInt.get(session.getLockTimeout());
             break;
+        case DISK_SPACE_USED:
+            result = ValueLong.get(getDiskSpaceUsed(session, v0));
+            break;
         case CAST:
         case CONVERT: {
             v0 = v0.convertTo(dataType);
@@ -942,6 +947,13 @@ public class Function extends Expression implements FunctionCall {
         return false;
     }
 
+    private static long getDiskSpaceUsed(Session session, Value v0) {
+        Parser p = new Parser(session);
+        String sql = v0.getString();
+        Table table = p.parseTableName(sql);
+        return table.getDiskSpaceUsed();
+    }
+    
     private static Value getNullOrValue(Session session, Expression[] args, Value[] values, int i) {
         if (i >= args.length) {
             return null;

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

@@ -90,6 +90,10 @@ public class FunctionIndex extends BaseIndex {
         return functionTable.getRowCountApproximation();
     }
 
+    public long getDiskSpaceUsed() {
+        return 0;
+    }
+    
     public String getPlanSQL() {
         return "function";
     }

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

@@ -81,6 +81,10 @@ public class HashIndex extends BaseIndex {
         return rows.size();
     }
 
+    public long getDiskSpaceUsed() {
+        return 0;
+    }
+
     public void close(Session session) {
         // nothing to do
     }

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

@@ -156,6 +156,11 @@ public interface Index extends SchemaObject {
      */
     long getRowCountApproximation();
 
+    /**
+     * @return the estimated number of bytes of disk space used by this page and all child pages.
+     */
+    long getDiskSpaceUsed();
+    
     /**
      * Compare two rows.
      *

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

@@ -246,4 +246,7 @@ public class LinkedIndex extends BaseIndex {
         return rowCount;
     }
 
+    public long getDiskSpaceUsed() {
+        return 0;
+    }
 }

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

@@ -97,6 +97,10 @@ public class MetaIndex extends BaseIndex {
         return MetaTable.ROW_COUNT_APPROXIMATION;
     }
 
+    public long getDiskSpaceUsed() {
+        return meta.getDiskSpaceUsed();
+    }
+    
     public String getPlanSQL() {
         return "meta";
     }

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

@@ -302,6 +302,10 @@ public class MultiVersionIndex implements Index {
         return base.getRowCountApproximation();
     }
 
+    public long getDiskSpaceUsed() {
+        return base.getDiskSpaceUsed();
+    }
+    
     public Index getBaseIndex() {
         return base;
     }

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

@@ -300,6 +300,10 @@ public class PageBtreeIndex extends PageIndex {
         return tableData.getRowCountApproximation();
     }
 
+    public long getDiskSpaceUsed() {
+        return tableData.getDiskSpaceUsed();
+    }
+    
     public long getRowCount(Session session) {
         return rowCount;
     }

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

@@ -88,6 +88,11 @@ abstract class PageData extends Page {
      */
     abstract void setRowCountStored(int rowCount);
 
+    /**
+     * @return the estimated number of bytes of disk space used by this page and all child pages.
+     */
+    abstract long getDiskSpaceUsed();
+
     /**
      * Find an entry by key.
      *
@@ -229,7 +234,7 @@ abstract class PageData extends Page {
         // to how much memory a row needs on average
         return memoryEstimated;
     }
-
+    
     int getParentPageId() {
         return parentPageId;
     }

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

@@ -427,6 +427,11 @@ public class PageDataIndex extends PageIndex {
         return rowCount;
     }
 
+    public long getDiskSpaceUsed() {
+        PageData root = getPage(rootPageId, 0);
+        return root.getDiskSpaceUsed();
+    }
+    
     public String getCreateSQL() {
         return null;
     }

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

@@ -451,6 +451,10 @@ public class PageDataLeaf extends PageData {
         // ignore
     }
 
+    long getDiskSpaceUsed() {
+        return index.getPageStore().getPageSize();
+    }
+    
     public void write() {
         writeData();
         index.getPageStore().writePage(getPos(), data);

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

@@ -277,7 +277,7 @@ public class PageDataNode extends PageData {
                 int child = childPageIds[i];
                 PageData page = index.getPage(child, getPos());
                 if (getPos() == page.getPos()) {
-                    throw DbException.throwInternalError("Page it its own child: " + getPos());
+                    throw DbException.throwInternalError("Page is its own child: " + getPos());
                 }
                 count += page.getRowCount();
                 index.getDatabase().setProgress(DatabaseEventListener.STATE_SCAN_FILE,
@@ -288,6 +288,21 @@ public class PageDataNode extends PageData {
         return rowCount;
     }
 
+    long getDiskSpaceUsed() {
+        long count = 0;
+        for (int i = 0; i < entryCount + 1; i++) {
+            int child = childPageIds[i];
+            PageData page = index.getPage(child, getPos());
+            if (getPos() == page.getPos()) {
+                throw DbException.throwInternalError("Page is its own child: " + getPos());
+            }
+            count += page.getDiskSpaceUsed();
+            index.getDatabase().setProgress(DatabaseEventListener.STATE_SCAN_FILE,
+                    index.getTable() + "." + index.getName(), (int) (count>>16), Integer.MAX_VALUE);
+        }
+        return count;
+    }
+    
     void setRowCountStored(int rowCount) {
         this.rowCount = rowCount;
         if (rowCountStored != rowCount) {

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

@@ -117,6 +117,10 @@ public class PageDelegateIndex extends PageIndex {
         return mainIndex.getRowCountApproximation();
     }
 
+    public long getDiskSpaceUsed() {
+        return mainIndex.getDiskSpaceUsed();
+    }
+    
     public void writeRowCount() {
         // ignore
     }

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

@@ -95,4 +95,7 @@ public class RangeIndex extends BaseIndex {
         return rangeTable.getRowCountApproximation();
     }
 
+    public long getDiskSpaceUsed() {
+        return 0;
+    }
 }

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

@@ -232,6 +232,10 @@ public class ScanIndex extends BaseIndex {
         return rowCount;
     }
 
+    public long getDiskSpaceUsed() {
+        return 0;
+    }
+    
     public String getPlanSQL() {
         return table.getSQL() + ".tableScan";
     }

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

@@ -383,4 +383,8 @@ public class TreeIndex extends BaseIndex {
         return rowCount;
     }
 
+    public long getDiskSpaceUsed() {
+        return 0;
+    }
+
 }

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

@@ -375,6 +375,10 @@ public class ViewIndex extends BaseIndex {
         return 0;
     }
 
+    public long getDiskSpaceUsed() {
+        return 0;
+    }
+
     public boolean isRecursive() {
         return recursive;
     }

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

@@ -118,4 +118,8 @@ public class MVDelegateIndex extends BaseIndex {
         return mainIndex.getRowCountApproximation();
     }
 
+    public long getDiskSpaceUsed() {
+        return 0;
+    }
+
 }

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

@@ -187,6 +187,10 @@ public class MVPrimaryIndex extends BaseIndex {
         return map.getSize();
     }
 
+    public long getDiskSpaceUsed() {
+        return 0; // TODO
+    }
+
     @Override
     public void checkRename() {
         // ok

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

@@ -150,6 +150,10 @@ public class MVSecondaryIndex extends BaseIndex {
         return map.getSize();
     }
 
+    public long getDiskSpaceUsed() {
+        return 0; // TODO
+    }
+
     @Override
     public void checkRename() {
         // ok

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

@@ -418,6 +418,10 @@ public class MVTable extends TableBase {
         return primaryIndex.getRowCountApproximation();
     }
 
+    public long getDiskSpaceUsed() {
+        return primaryIndex.getDiskSpaceUsed();
+    }
+
     @Override
     public void checkRename() {
         // ok

h2/src/main/org/h2/table/FunctionTable.java

@@ -216,6 +216,10 @@ public class FunctionTable extends Table {
     public long getRowCountApproximation() {
         return rowCount;
     }
+    
+    public long getDiskSpaceUsed() {
+        return 0;
+    }
 
     public boolean isDeterministic() {
         return function.isDeterministic();

h2/src/main/org/h2/table/MetaTable.java

@@ -1801,6 +1801,10 @@ public class MetaTable extends Table {
         return ROW_COUNT_APPROXIMATION;
     }
 
+    public long getDiskSpaceUsed() {
+        return 0;
+    }
+
     public boolean isDeterministic() {
         return true;
     }

h2/src/main/org/h2/table/RangeTable.java

@@ -167,6 +167,10 @@ public class RangeTable extends Table {
         return 100;
     }
 
+    public long getDiskSpaceUsed() {
+        return 0;
+    }
+
     public boolean isDeterministic() {
         return true;
     }

h2/src/main/org/h2/table/RegularTable.java

@@ -724,6 +724,11 @@ public class RegularTable extends TableBase {
     public long getRowCountApproximation() {
         return scanIndex.getRowCountApproximation();
     }
+    
+    @Override
+    public long getDiskSpaceUsed() {
+        return scanIndex.getDiskSpaceUsed();
+    }
 
     public void setCompareMode(CompareMode compareMode) {
         this.compareMode = compareMode;

h2/src/main/org/h2/table/Table.java

@@ -293,6 +293,8 @@ public abstract class Table extends SchemaObjectBase {
      */
     public abstract long getRowCountApproximation();
 
+    public abstract long getDiskSpaceUsed();
+    
     /**
      * Get the row id column if this table has one.
      *

h2/src/main/org/h2/table/TableLink.java

@@ -598,6 +598,10 @@ public class TableLink extends Table {
         return ROW_COUNT_APPROXIMATION;
     }
 
+    public long getDiskSpaceUsed() {
+        return 0;
+    }
+
     /**
      * Add this prepared statement to the list of cached statements.
      *

h2/src/main/org/h2/table/TableView.java

@@ -437,6 +437,10 @@ public class TableView extends Table {
         return ROW_COUNT_APPROXIMATION;
     }
 
+    public long getDiskSpaceUsed() {
+        return 0;
+    }
+
     public int getParameterOffset() {
         return topQuery == null ? 0 : topQuery.getParameters().size();
     }

h2/src/test/org/h2/test/db/TestTableEngines.java

@@ -148,6 +148,10 @@ public class TestTableEngines extends TestBase {
                     return table.getRowCountApproximation();
                 }
 
+                public long getDiskSpaceUsed() {
+                    return table.getDiskSpaceUsed();
+                }
+                
                 public long getRowCount(Session session) {
                     return table.getRowCount(session);
                 }
@@ -257,6 +261,10 @@ public class TestTableEngines extends TestBase {
                 return row == null ? 0 : 1;
             }
 
+            public long getDiskSpaceUsed() {
+                return 0;
+            }
+
             @Override
             public Index getScanIndex(Session session) {
                 return scanIndex;

h2/src/test/org/h2/test/test-1.3.txt

@@ -9972,3 +9972,13 @@ select * from word;
 drop table word;
 > ok
 
+create table test(id int, name varchar);
+> ok
+
+insert into test values(5, 'b'), (5, 'b'), (20, 'a');
+> update count: 3
+
+CALL DISK_SPACE_USED('test');
+> DISK_SPACE_USED('test')
+> -----------------------
+> 2048