# 读取时合并（MoR）创建表示例
<a name="querying-hudi-merge-on-read-create-table-examples"></a>

Hudi 在元存储中为 MoR 创建了两个表：一个用于快照查询的表，一个用于读取优化查询的表。两个表都可查询。在 0.5.1 之前的 Hudi 版本中，用于读优化查询的表具有您在创建表时指定的名称。从 Hudi 版本 0.5.1 开始，表名将默认以 `_ro` 为后缀。用于快照查询的表的名称是指定的名称，其中附加了 `_rt`。

## 未分区的读取时合并（MoR）表
<a name="querying-hudi-nonpartitioned-merge-on-read-table"></a>

以下示例在 Athena 中创建了一个未分区的 MoR 表用于读取优化查询。请注意，读取优化查询使用输入格式 `HoodieParquetInputFormat`。

```
CREATE EXTERNAL TABLE `nonpartition_mor`(
  `_hoodie_commit_time` string, 
  `_hoodie_commit_seqno` string, 
  `_hoodie_record_key` string, 
  `_hoodie_partition_path` string, 
  `_hoodie_file_name` string, 
  `event_id` string, 
  `event_time` string, 
  `event_name` string, 
  `event_guests` int, 
  `event_type` string)
ROW FORMAT SERDE 
  'org.apache.hadoop.hive.ql.io.parquet.serde.ParquetHiveSerDe' 
STORED AS INPUTFORMAT 
  'org.apache.hudi.hadoop.HoodieParquetInputFormat' 
OUTPUTFORMAT 
  'org.apache.hadoop.hive.ql.io.parquet.MapredParquetOutputFormat' 
LOCATION
  's3://amzn-s3-demo-bucket/folder/nonpartition_mor/'
```

以下示例在 Athena 中创建了一个未分区的 MoR 表用于快照查询。对于快照查询，请使用输入格式 `HoodieParquetRealtimeInputFormat`。

```
CREATE EXTERNAL TABLE `nonpartition_mor_rt`(
  `_hoodie_commit_time` string, 
  `_hoodie_commit_seqno` string, 
  `_hoodie_record_key` string, 
  `_hoodie_partition_path` string, 
  `_hoodie_file_name` string, 
  `event_id` string, 
  `event_time` string, 
  `event_name` string, 
  `event_guests` int, 
  `event_type` string)
ROW FORMAT SERDE 
  'org.apache.hadoop.hive.ql.io.parquet.serde.ParquetHiveSerDe' 
STORED AS INPUTFORMAT 
  'org.apache.hudi.hadoop.realtime.HoodieParquetRealtimeInputFormat' 
OUTPUTFORMAT 
  'org.apache.hadoop.hive.ql.io.parquet.MapredParquetOutputFormat' 
LOCATION
  's3://amzn-s3-demo-bucket/folder/nonpartition_mor/'
```

## 已分区的读取时合并（MoR）表
<a name="querying-hudi-partitioned-merge-on-read-table"></a>

以下示例在 Athena 中创建了一个已分区的 MoR 表用于读取优化查询。

```
CREATE EXTERNAL TABLE `partition_mor`(
  `_hoodie_commit_time` string, 
  `_hoodie_commit_seqno` string, 
  `_hoodie_record_key` string, 
  `_hoodie_partition_path` string, 
  `_hoodie_file_name` string, 
  `event_id` string, 
  `event_time` string, 
  `event_name` string, 
  `event_guests` int)
PARTITIONED BY ( 
  `event_type` string)
ROW FORMAT SERDE 
  'org.apache.hadoop.hive.ql.io.parquet.serde.ParquetHiveSerDe' 
STORED AS INPUTFORMAT 
  'org.apache.hudi.hadoop.HoodieParquetInputFormat' 
OUTPUTFORMAT 
  'org.apache.hadoop.hive.ql.io.parquet.MapredParquetOutputFormat'
LOCATION
  's3://amzn-s3-demo-bucket/folder/partition_mor/'
```

以下 `ALTER TABLE ADD PARTITION` 示例将两个分区添加到了示例 `partition_mor` 表。

```
ALTER TABLE partition_mor ADD
  PARTITION (event_type = 'one') LOCATION 's3://amzn-s3-demo-bucket/folder/partition_mor/one/'
  PARTITION (event_type = 'two') LOCATION 's3://amzn-s3-demo-bucket/folder/partition_mor/two/'
```

以下示例在 Athena 中创建了一个已分区的 MoR 表用于快照查询。

```
CREATE EXTERNAL TABLE `partition_mor_rt`(
  `_hoodie_commit_time` string, 
  `_hoodie_commit_seqno` string, 
  `_hoodie_record_key` string, 
  `_hoodie_partition_path` string, 
  `_hoodie_file_name` string, 
  `event_id` string, 
  `event_time` string, 
  `event_name` string, 
  `event_guests` int)
PARTITIONED BY ( 
  `event_type` string)
ROW FORMAT SERDE 
  'org.apache.hadoop.hive.ql.io.parquet.serde.ParquetHiveSerDe'
STORED AS INPUTFORMAT 
  'org.apache.hudi.hadoop.realtime.HoodieParquetRealtimeInputFormat'
OUTPUTFORMAT 
  'org.apache.hadoop.hive.ql.io.parquet.MapredParquetOutputFormat'
LOCATION
  's3://amzn-s3-demo-bucket/folder/partition_mor/'
```

同样，以下 `ALTER TABLE ADD PARTITION` 示例将两个分区添加到了示例 `partition_mor_rt` 表。

```
ALTER TABLE partition_mor_rt ADD
  PARTITION (event_type = 'one') LOCATION 's3://amzn-s3-demo-bucket/folder/partition_mor/one/'
  PARTITION (event_type = 'two') LOCATION 's3://amzn-s3-demo-bucket/folder/partition_mor/two/'
```