Sh-Zh-7 commented on code in PR #14213: URL: https://github.com/apache/iotdb/pull/14213#discussion_r1915327778
########## iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/execution/operator/process/window/function/value/LagFunction.java: ########## @@ -0,0 +1,93 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, + * software distributed under the License is distributed on an + * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + * KIND, either express or implied. See the License for the + * specific language governing permissions and limitations + * under the License. + */ + +package org.apache.iotdb.db.queryengine.execution.operator.process.window.function.value; + +import org.apache.iotdb.db.queryengine.execution.operator.process.window.function.WindowFunction; +import org.apache.iotdb.db.queryengine.execution.operator.process.window.partition.Partition; + +import org.apache.tsfile.block.column.ColumnBuilder; + +public class LagFunction implements WindowFunction { + private final int channel; + private final Integer offset; + private final Object defaultVal; + private final boolean ignoreNull; + + public LagFunction(int channel, Integer offset, Object defaultVal, boolean ignoreNull) { + this.channel = channel; + this.offset = offset == null ? 1 : offset; + this.defaultVal = defaultVal; + this.ignoreNull = ignoreNull; + } + + @Override + public void reset() {} + + @Override + public void transform( + Partition partition, + ColumnBuilder builder, + int index, + int frameStart, + int frameEnd, + int peerGroupStart, + int peerGroupEnd) { + int pos; + if (ignoreNull) { + int nonNullCount = 0; + pos = index - 1; + while (pos >= 0) { + if (!partition.isNull(channel, pos)) { + nonNullCount++; + if (nonNullCount == offset) { + break; + } + } + + pos--; + } + } else { + pos = index - offset; + } + + if (pos >= 0) { + if (!partition.isNull(channel, pos)) { + partition.writeTo(builder, channel, pos); + } else { + builder.appendNull(); + } + } else if (defaultVal != null) { + // TODO: Replace write object Review Comment: Default value's type must be consistent with input's data type, it can be any data types. Personally I dont like `writeObject`, but it is convenient to do so. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
