@Override protected LocalResult queryWithoutCache(int maxRows, ResultTarget target) { if (maxRows != 0) { // maxRows is set (maxRows 0 means no limit) int l; if (limitExpr == null) { l = -1; } else { Value v = limitExpr.getValue(session); l = v == ValueNull.INSTANCE ? -1 : v.getInt(); } if (l < 0) { // for limitExpr, 0 means no rows, and -1 means no limit l = maxRows; } else { l = Math.min(l, maxRows); } limitExpr = ValueExpression.get(ValueInt.get(l)); } if (session.getDatabase().getSettings().optimizeInsertFromSelect) { if (unionType == UNION_ALL && target != null) { if (sort == null && !distinct && maxRows == 0 && offsetExpr == null && limitExpr == null) { left.query(0, target); right.query(0, target); return null; } } } int columnCount = left.getColumnCount(); LocalResult result = new LocalResult(session, expressionArray, columnCount); if (sort != null) { result.setSortOrder(sort); } if (distinct) { left.setDistinct(true); right.setDistinct(true); result.setDistinct(); } if (randomAccessResult) { result.setRandomAccess(); } switch (unionType) { case UNION: case EXCEPT: left.setDistinct(true); right.setDistinct(true); result.setDistinct(); break; case UNION_ALL: break; case INTERSECT: left.setDistinct(true); right.setDistinct(true); break; default: DbException.throwInternalError("type=" + unionType); } ResultInterface l = left.query(0); ResultInterface r = right.query(0); l.reset(); r.reset(); switch (unionType) { case UNION_ALL: case UNION: { while (l.next()) { result.addRow(convert(l.currentRow(), columnCount)); } while (r.next()) { result.addRow(convert(r.currentRow(), columnCount)); } break; } case EXCEPT: { while (l.next()) { result.addRow(convert(l.currentRow(), columnCount)); } while (r.next()) { result.removeDistinct(convert(r.currentRow(), columnCount)); } break; } case INTERSECT: { LocalResult temp = new LocalResult(session, expressionArray, columnCount); temp.setDistinct(); temp.setRandomAccess(); while (l.next()) { temp.addRow(convert(l.currentRow(), columnCount)); } while (r.next()) { Value[] values = convert(r.currentRow(), columnCount); if (temp.containsDistinct(values)) { result.addRow(values); } } break; } default: DbException.throwInternalError("type=" + unionType); } if (offsetExpr != null) { result.setOffset(offsetExpr.getValue(session).getInt()); } if (limitExpr != null) { Value v = limitExpr.getValue(session); if (v != ValueNull.INSTANCE) { result.setLimit(v.getInt()); } } result.done(); if (target != null) { while (result.next()) { target.addRow(result.currentRow()); } result.close(); return null; } return result; }
// 总共18条命令,这里包含16条 // 下面这两条在run方法中特殊处理 // SESSION_CANCEL_STATEMENT // SESSION_CHECK_KEY // 分三种级别,从大到小: SESSION级、COMMAND级、RESULT级 private void process() throws IOException { int operation = transfer.readInt(); switch (operation) { case SessionRemote.SESSION_PREPARE_READ_PARAMS: case SessionRemote.SESSION_PREPARE: { int id = transfer.readInt(); String sql = transfer.readString(); int old = session.getModificationId(); Command command = session.prepareLocal(sql); boolean readonly = command.isReadOnly(); cache.addObject(id, command); boolean isQuery = command.isQuery(); ArrayList<? extends ParameterInterface> params = command.getParameters(); transfer .writeInt(getState(old)) .writeBoolean(isQuery) .writeBoolean(readonly) .writeInt(params.size()); if (operation == SessionRemote.SESSION_PREPARE_READ_PARAMS) { for (ParameterInterface p : params) { ParameterRemote.writeMetaData(transfer, p); } } transfer.flush(); break; } case SessionRemote.SESSION_CLOSE: { stop = true; closeSession(); transfer.writeInt(SessionRemote.STATUS_OK).flush(); close(); break; } case SessionRemote.COMMAND_COMMIT: { // 并不是通过org.h2.jdbc.JdbcConnection.commit()触发,此方法是通过发送COMMIT SQL触发 // 触发SessionRemote.COMMAND_COMMIT的是在集群环境下,通过org.h2.engine.SessionRemote.autoCommitIfCluster()触发 if (commit == null) { commit = session.prepareLocal("COMMIT"); } int old = session.getModificationId(); commit.executeUpdate(); transfer.writeInt(getState(old)).flush(); break; } case SessionRemote.COMMAND_GET_META_DATA: { int id = transfer.readInt(); int objectId = transfer.readInt(); Command command = (Command) cache.getObject(id, false); ResultInterface result = command.getMetaData(); cache.addObject(objectId, result); int columnCount = result.getVisibleColumnCount(); transfer.writeInt(SessionRemote.STATUS_OK).writeInt(columnCount).writeInt(0); for (int i = 0; i < columnCount; i++) { ResultColumn.writeColumn(transfer, result, i); } transfer.flush(); break; } case SessionRemote.COMMAND_EXECUTE_QUERY: { int id = transfer.readInt(); int objectId = transfer.readInt(); int maxRows = transfer.readInt(); int fetchSize = transfer.readInt(); Command command = (Command) cache.getObject(id, false); setParameters(command); int old = session.getModificationId(); ResultInterface result; synchronized (session) { result = command.executeQuery(maxRows, false); } cache.addObject(objectId, result); int columnCount = result.getVisibleColumnCount(); int state = getState(old); transfer.writeInt(state).writeInt(columnCount); int rowCount = result.getRowCount(); transfer.writeInt(rowCount); for (int i = 0; i < columnCount; i++) { ResultColumn.writeColumn(transfer, result, i); } int fetch = Math.min(rowCount, fetchSize); for (int i = 0; i < fetch; i++) { sendRow(result); } transfer.flush(); break; } case SessionRemote.COMMAND_EXECUTE_UPDATE: { int id = transfer.readInt(); Command command = (Command) cache.getObject(id, false); // if(command!=null)throw new Error(); setParameters(command); int old = session.getModificationId(); int updateCount; synchronized (session) { updateCount = command.executeUpdate(); } int status; if (session.isClosed()) { status = SessionRemote.STATUS_CLOSED; } else { status = getState(old); } transfer.writeInt(status).writeInt(updateCount).writeBoolean(session.getAutoCommit()); transfer.flush(); break; } case SessionRemote.COMMAND_CLOSE: { int id = transfer.readInt(); Command command = (Command) cache.getObject(id, true); if (command != null) { command.close(); cache.freeObject(id); } break; } case SessionRemote.RESULT_FETCH_ROWS: { int id = transfer.readInt(); int count = transfer.readInt(); ResultInterface result = (ResultInterface) cache.getObject(id, false); transfer.writeInt(SessionRemote.STATUS_OK); for (int i = 0; i < count; i++) { sendRow(result); } transfer.flush(); break; } case SessionRemote.RESULT_RESET: { int id = transfer.readInt(); ResultInterface result = (ResultInterface) cache.getObject(id, false); result.reset(); break; } case SessionRemote.RESULT_CLOSE: { int id = transfer.readInt(); ResultInterface result = (ResultInterface) cache.getObject(id, true); if (result != null) { result.close(); cache.freeObject(id); } break; } case SessionRemote.CHANGE_ID: { int oldId = transfer.readInt(); int newId = transfer.readInt(); Object obj = cache.getObject(oldId, false); cache.freeObject(oldId); cache.addObject(newId, obj); break; } case SessionRemote.SESSION_SET_ID: { sessionId = transfer.readString(); transfer.writeInt(SessionRemote.STATUS_OK).flush(); break; } case SessionRemote.SESSION_SET_AUTOCOMMIT: { boolean autoCommit = transfer.readBoolean(); session.setAutoCommit(autoCommit); transfer.writeInt(SessionRemote.STATUS_OK).flush(); break; } case SessionRemote.SESSION_HAS_PENDING_TRANSACTION: { transfer .writeInt(SessionRemote.STATUS_OK) .writeInt(session.hasPendingTransaction() ? 1 : 0) .flush(); break; } case SessionRemote.LOB_READ: { long lobId = transfer.readLong(); byte[] hmac; CachedInputStream in; boolean verifyMac; if (clientVersion >= Constants.TCP_PROTOCOL_VERSION_11) { if (clientVersion >= Constants.TCP_PROTOCOL_VERSION_12) { hmac = transfer.readBytes(); verifyMac = true; } else { hmac = null; verifyMac = false; } in = lobs.get(lobId); if (in == null && verifyMac) { in = new CachedInputStream(null); lobs.put(lobId, in); } } else { verifyMac = false; hmac = null; in = lobs.get(lobId); } long offset = transfer.readLong(); int length = transfer.readInt(); if (verifyMac) { transfer.verifyLobMac(hmac, lobId); } if (in == null) { throw DbException.get(ErrorCode.OBJECT_CLOSED); } if (in.getPos() != offset) { LobStorageInterface lobStorage = session.getDataHandler().getLobStorage(); InputStream lobIn = lobStorage.getInputStream(lobId, hmac, -1); in = new CachedInputStream(lobIn); lobs.put(lobId, in); lobIn.skip(offset); } // limit the buffer size length = Math.min(16 * Constants.IO_BUFFER_SIZE, length); byte[] buff = new byte[length]; length = IOUtils.readFully(in, buff, 0, length); transfer.writeInt(SessionRemote.STATUS_OK); transfer.writeInt(length); transfer.writeBytes(buff, 0, length); transfer.flush(); break; } default: trace("Unknown operation: " + operation); closeSession(); close(); } }
public Cursor find(Session session, SearchRow first, SearchRow last) { if (recursive) { if (view.getRecursiveResult() != null) { ResultInterface r = view.getRecursiveResult(); r.reset(); return new ViewCursor(table, r); } if (query == null) { query = (Query) createSession.prepare(querySQL, true); planSQL = query.getPlanSQL(); } if (!(query instanceof SelectUnion)) { throw DbException.get(ErrorCode.SYNTAX_ERROR_2, "recursive queries without UNION ALL"); } SelectUnion union = (SelectUnion) query; if (union.getUnionType() != SelectUnion.UNION_ALL) { throw DbException.get(ErrorCode.SYNTAX_ERROR_2, "recursive queries without UNION ALL"); } Query left = union.getLeft(); ResultInterface r = left.query(0); LocalResult result = union.getEmptyResult(); while (r.next()) { result.addRow(r.currentRow()); } Query right = union.getRight(); r.reset(); view.setRecursiveResult(r); while (true) { r = right.query(0); if (r.getRowCount() == 0) { break; } while (r.next()) { result.addRow(r.currentRow()); } r.reset(); view.setRecursiveResult(r); } return new ViewCursor(table, result); } ArrayList<Parameter> paramList = query.getParameters(); for (int i = 0; originalParameters != null && i < originalParameters.size(); i++) { Parameter orig = originalParameters.get(i); int idx = orig.getIndex(); Value value = orig.getValue(session); setParameter(paramList, idx, value); } int len; if (first != null) { len = first.getColumnCount(); } else if (last != null) { len = last.getColumnCount(); } else { len = 0; } int idx = originalParameters == null ? 0 : originalParameters.size(); idx += view.getParameterOffset(); for (int i = 0; i < len; i++) { if (first != null) { Value v = first.getValue(i); if (v != null) { int x = idx++; setParameter(paramList, x, v); } } // for equality, only one parameter is used (first == last) if (last != null && indexMasks[i] != IndexCondition.EQUALITY) { Value v = last.getValue(i); if (v != null) { int x = idx++; setParameter(paramList, x, v); } } } ResultInterface result = query.query(0); return new ViewCursor(table, result); }