Presto UDAF 输出数组(array)

1.版本0.189之前的使用:

@OutputFunction("array(" + StandardTypes.BIGINT + ")") public static void output(SliceState state, BlockBuilder out) { // 获取状态 Slice slice = state.getSlice(); // 数据为空, 返回一个空数组 if (null == slice) { BlockBuilder blockBuilder = BigintType.BIGINT.createBlockBuilder(new BlockBuilderStatus(), 0); out.writeObject(blockBuilder.build()); out.closeEntry(); return; } // 构造结果: [A:100, B:50, C:10, ......] BlockBuilder blockBuilder = BigintType.BIGINT.createBlockBuilder(new BlockBuilderStatus(), slice.length() / 4); for (int index = 0; index < slice.length(); index += 4) { BigintType.BIGINT.writeLong(blockBuilder, slice.getInt(index)); } // 返回结果 out.writeObject(blockBuilder.build()); out.closeEntry(); }

 

2.版本0.189之后请使用：

@OutputFunction("array(bigint)") public static void output(@AggregationState SliceState state, BlockBuilder out) { // 获取状态 Slice slice = state.getSlice(); // 数据为空, 返回一个空数组 if (slice == null) { out.appendNull(); return; } // 构造结果: [A:100, B:50, C:10, ......] BlockBuilder blockBuilder = out.beginBlockEntry(); for (int index = 0; index < slice.length(); index += 4) { BIGINT.writeLong(blockBuilder, slice.getInt(index)); } //返回结果 out.closeEntry(); }

上面两段代码实现的逻辑相同