GreptimeTeam · xtang · Oct 12, 2023 · Oct 12, 2023 · Oct 12, 2023 · Oct 12, 2023
@@ -45,14 +45,14 @@ Creates a new table in the `db` database or the current database in use:
 ```sql
 CREATE TABLE [IF NOT EXISTS] [db.]table_name
 (
-    name1 [type1] [NULL|NOT NULL] [DEFAULT expr1] [TIME INDEX] [PRIMARY KEY] COMMENT comment,
-    name2 [type2] [NULL|NOT NULL] [DEFAULT expr2] [TIME INDEX] [PRIMARY KEY] COMMENT comment,
-    ...,
-    [TIME INDEX (name)],
-    [PRIMARY KEY(name1, name2,...)]
-) ENGINE = engine WITH([ttl | regions] = expr, ...)
+    column1 type1 [NULL | NOT NULL] [DEFAULT expr1] [TIME INDEX] [PRIMARY KEY] [COMMENT comment1],
+    column2 type2 [NULL | NOT NULL] [DEFAULT expr2] [TIME INDEX] [PRIMARY KEY] [COMMENT comment2],
+    ...
+    [TIME INDEX (column)],
+    [PRIMARY KEY(column1, column2, ...)]
+) ENGINE = engine WITH([TTL | REGIONS] = expr, ...)
 [
-  PARTITION BY RANGE COLUMNS(name1, name2, ...) (
+  PARTITION BY RANGE COLUMNS(column1, column2, ...) (
     PARTITION r0 VALUES LESS THAN (expr1),
     PARTITION r1 VALUES LESS THAN (expr2),
     ...
@@ -61,7 +61,7 @@ CREATE TABLE [IF NOT EXISTS] [db.]table_name
 ```
 
 The table schema is specified by the brackets before the `ENGINE`. The table schema is a list of column definitions and table constraints.
-A column definition includes the column `name`, `type`, and options such as nullable or default values, etc. Please see below.
+A column definition includes the column `column_name`, `type`, and options such as nullable or default values, etc. Please see below.
 
 ### Table constraints
 
@@ -155,34 +155,35 @@ TODO by MichaelScofield
 Creates a new file external table in the `db` database or the current database in use:
 
 ```sql
-CREATE EXTERNAL TABLE [IF NOT EXISTS] [<database>.]<table_name>
+CREATE EXTERNAL TABLE [IF NOT EXISTS] [db.]table_name
 [
  (
-    <col_name> <col_type> [NULL | NOT NULL] [COMMENT "<comment>"]
- )
-]
-[ WITH
- (
-   LOCATION = 'url'
-   [,FORMAT =  { csv | json | parquet } ]
-   [,PATTERN = '<regex_pattern>' ]
-   [,ENDPOINT = '<uri>' ]
-   [,ACCESS_KEY_ID = '<key_id>' ]
-   [,SECRET_ACCESS_KEY = '<access_key>' ]
-   [,SESSION_TOKEN = '<token>' ]
-   [,REGION = '<region>' ]
-   [,ENABLE_VIRTUAL_HOST_STYLE = '<boolean>']
-   ..
+    column1 type1 [NULL | NOT NULL] [DEFAULT expr1] [TIME INDEX] [PRIMARY KEY] [COMMENT comment1],
+    column2 type2 [NULL | NOT NULL] [DEFAULT expr2] [TIME INDEX] [PRIMARY KEY] [COMMENT comment2],
+    ...
+    [TIME INDEX (column)],
+    [PRIMARY KEY(column1, column2, ...)]
  )
-]
+] WITH (
+  LOCATION = url,
+  FORMAT =  { 'CSV' | 'JSON' | 'PARQUET' | 'ORC' }
+  [,PATTERN = regex_pattern ]
+  [,REGION = region ]
+  [,ENDPOINT = uri ]
+  [,ACCESS_KEY_ID = key_id ]
+  [,SECRET_ACCESS_KEY = access_key ]
+  [,ENABLE_VIRTUAL_HOST_STYLE = { TRUE | FALSE }]
+  [,SESSION_TOKEN = token ]
+  ...
+)
 ```
 
 ### Table options
 
 | Option     | Description                                                                     | Required     |
 | ---------- | ------------------------------------------------------------------------------- | ------------ |
 | `LOCATION` | External files locations, e.g., `s3://<bucket>[<path>]`, `/<path>/[<filename>]` | **Required** |
-| `FORMAT`   | Target file(s) format, e.g., JSON, CSV, Parquet                                 | **Required** |
+| `FORMAT`   | Target file(s) format, e.g., JSON, CSV, Parquet, ORC                            | **Required** |
 | `PATTERN`  | Use regex to match files. e.g., `*_today.parquet`                               | Optional     |
 
 #### S3
@@ -198,21 +199,21 @@ CREATE EXTERNAL TABLE [IF NOT EXISTS] [<database>.]<table_name>
 
 ### Time Index Column
 
-When creating an external table using the `CREATE EXTERNAL TABLE` statement, you are required to use the `TIME INDEX` constraint to specify a time index column.
+When creating an external table using the `CREATE EXTERNAL TABLE` statement, you are required to use the `TIME INDEX` constraint to specify a Time Index column.
 
 ### Examples
 
-You can create an external table without any columns definitions:
+You can create an external table without columns definitions, the column definitions will be automatically inferred:
 
 ```sql
 CREATE EXTERNAL TABLE IF NOT EXISTS city WITH (location='/var/data/city.csv',format='csv');
 ```
 
-In this example, since we have not explicitly defined the columns of the table, the `CREATE EXTERNAL TABLE` statement will infer the `Time Index` column according to the following rules:
+In this example, we did not explicitly define the columns of the table. To satisfy the requirement that the external table must specify a **Time Index** column, the `CREATE EXTERNAL TABLE` statement will infer the Time Index column according to the following rules:
 
-1. If the `Time Index` column can be inferred from the file metadata, then that column will be used as the `Time Index` column.
-2. If there is a column named `greptime_timestamp` (the type of this column must be `TIMESTAMP`, otherwise, an error will be thrown), then this column will be used as the `Time Index` column.
-3. Otherwise, a column named `greptime_timestamp` will be automatically created as the `Time Index` column, and a `DEFAULT '1970-01-01 00:00:00+0000'` constraint will be added.
+1. If the Time Index column can be inferred from the file metadata, then that column will be used as the Time Index column.
+2. If there is a column named `greptime_timestamp` (the type of this column must be `TIMESTAMP`, otherwise, an error will be thrown), then this column will be used as the Time Index column.
+3. Otherwise, a column named `greptime_timestamp` will be automatically created as the Time Index column, and a `DEFAULT '1970-01-01 00:00:00+0000'` constraint will be added.
 
 Or
 
@@ -227,4 +228,4 @@ CREATE EXTERNAL TABLE city (
 ) WITH (location='/var/data/city.csv', format='csv');
 ```
 
-In this example, we explicitly defined the `ts` column as the `Time Index` column. If there is no suitable `Time Index` column in the file, you can also create a placeholder column and add a `DEFAULT <expr>` constraint.
+In this example, we explicitly defined the `ts` column as the Time Index column. If there is no suitable Time Index column in the file, you can also create a placeholder column and add a `DEFAULT expr` constraint.
@@ -2,7 +2,7 @@
 
 ## Query on a file
 
-Currently, we support queries on `Parquet`, `CSV`, and `NDJson` format file(s).
+Currently, we support queries on `Parquet`, `CSV`, `ORC`, and `NDJson` format file(s).
 
 We use the [Taxi Zone Lookup Table](https://d37ci6vzurychx.cloudfront.net/misc/taxi+_zone_lookup.csv) data as an example.
 

@@ -45,14 +45,14 @@ CREATE DATABASE IF NOT EXISTS test;
 ```sql
 CREATE TABLE [IF NOT EXISTS] [db.]table_name
 (
-    name1 [type1] [NULL|NOT NULL] [DEFAULT expr1] [TIME INDEX] [PRIMARY KEY] COMMENT comment,
-    name2 [type2] [NULL|NOT NULL] [DEFAULT expr2] [TIME INDEX] [PRIMARY KEY] COMMENT comment,
-    ...,
-    [TIME INDEX (name)],
-    [PRIMARY KEY(name1, name2,...)]
-) ENGINE = engine WITH([ttl | regions] = expr, ...)
+    column1 type1 [NULL | NOT NULL] [DEFAULT expr1] [TIME INDEX] [PRIMARY KEY] [COMMENT comment1],
+    column2 type2 [NULL | NOT NULL] [DEFAULT expr2] [TIME INDEX] [PRIMARY KEY] [COMMENT comment2],
+    ...
+    [TIME INDEX (column)],
+    [PRIMARY KEY(column1, column2, ...)]
+) ENGINE = engine WITH([TTL | REGIONS] = expr, ...)
 [
-  PARTITION BY RANGE COLUMNS(name1, name2, ...) (
+  PARTITION BY RANGE COLUMNS(column1, column2, ...) (
     PARTITION r0 VALUES LESS THAN (expr1),
     PARTITION r1 VALUES LESS THAN (expr2),
     ...
@@ -158,34 +158,35 @@ TODO by MichaelScofield
 在 `db` 或当前数据库中创建新的文件外部表：
 
 ```sql
-CREATE EXTERNAL TABLE [IF NOT EXISTS] [<database>.]<table_name>
+CREATE EXTERNAL TABLE [IF NOT EXISTS] [db.]table_name
 [
  (
-    <col_name> <col_type> [NULL | NOT NULL] [COMMENT "<comment>"]
- )
-]
-[ WITH
- (
-   LOCATION = 'url'
-   [,FORMAT =  { csv | json | parquet } ]
-   [,PATTERN = '<regex_pattern>' ]
-   [,ENDPOINT = '<uri>' ]
-   [,ACCESS_KEY_ID = '<key_id>' ]
-   [,SECRET_ACCESS_KEY = '<access_key>' ]
-   [,SESSION_TOKEN = '<token>' ]
-   [,REGION = '<region>' ]
-   [,ENABLE_VIRTUAL_HOST_STYLE = '<boolean>']
-   ..
+    column1 type1 [NULL | NOT NULL] [DEFAULT expr1] [TIME INDEX] [PRIMARY KEY] [COMMENT comment1],
+    column2 type2 [NULL | NOT NULL] [DEFAULT expr2] [TIME INDEX] [PRIMARY KEY] [COMMENT comment2],
+    ...
+    [TIME INDEX (column)],
+    [PRIMARY KEY(column1, column2, ...)]
  )
-]
+] WITH (
+  LOCATION = url,
+  FORMAT =  { 'CSV' | 'JSON' | 'PARQUET' | 'ORC' }
+  [,PATTERN = regex_pattern ]
+  [,REGION = region ]
+  [,ENDPOINT = uri ]
+  [,ACCESS_KEY_ID = key_id ]
+  [,SECRET_ACCESS_KEY = access_key ]
+  [,ENABLE_VIRTUAL_HOST_STYLE = { TRUE | FALSE }]
+  [,SESSION_TOKEN = token ]
+  ...
+)
 ```
 
 ### 表选项
 
 | 选项       | 描述                                                               | 是否必需 |
 | ---------- | ------------------------------------------------------------------ | -------- |
 | `LOCATION` | 外部表的位置，例如 `s3://<bucket>[<path>]`, `/<path>/[<filename>]` | **是**   |
-| `FORMAT`   | 目标文件的格式，例如 JSON，CSV，Parquet                            | **是**   |
+| `FORMAT`   | 目标文件的格式，例如 JSON，CSV，Parquet, ORC                         | **是**   |
 | `PATTERN`  | 使用正则来匹配文件，例如 `*_today.parquet`                         | 可选     |
 
 #### S3
@@ -205,13 +206,13 @@ CREATE EXTERNAL TABLE [IF NOT EXISTS] [<database>.]<table_name>
 
 ### 示例
 
-你可以在创建表时不带有列定义：
+你可以在创建外部表时不带有列定义，列定义将会被自动推断：
 
 ```sql
 CREATE EXTERNAL TABLE IF NOT EXISTS city WITH (location='/var/data/city.csv',format='csv');
 ```
 
-在这个例子中，我们没有明确定义表的列，因此 `CREATE EXTERNAL TABLE` 语句会由下列规则推断出时间索引列：
+在这个例子中，我们没有明确定义表的列，为满足外边表必须指定**时间索引列**的要求，`CREATE EXTERNAL TABLE` 语句会依据下述规则推断出时间索引列：
 
 1. 如果可以从文件元数据中推断出时间索引列，那么就用该列作为时间索引列。
 2. 如果存在名为 `greptime_timestamp` 的列（该列的类型必须为 `TIMESTAMP`，否则将抛出错误），那么就用该列作为时间索引列。
@@ -230,4 +231,4 @@ CREATE EXTERNAL TABLE city (
 ) WITH (location='/var/data/city.csv', format='csv');
 ```
 
-在这个例子中，我们明确定义了 `ts` 列作为时间索引列。如果在文件中没有适合的时间索引列，你也可以创建一个占位符列，并添加 `DEFAULT <expr>` 约束。
+在这个例子中，我们明确定义了 `ts` 列作为时间索引列。如果在文件中没有适合的时间索引列，你也可以创建一个占位符列，并添加 `DEFAULT expr` 约束。
@@ -2,7 +2,7 @@
 
 ## 对文件进行查询
 
-目前，我们支持 `Parquet`、`CSV` 和 `NDJson` 格式文件的查询。
+目前，我们支持 `Parquet`、`CSV`、`ORC` 和 `NDJson` 格式文件的查询。
 
 以 [Taxi Zone Lookup Table](https://d37ci6vzurychx.cloudfront.net/misc/taxi+_zone_lookup.csv) 数据为例。
 
@@ -36,7 +36,7 @@ DESC TABLE taxi_zone_lookup;
 ```
 
 :::tip 注意
-在这里，你可能会注意到出现了一个 `greptime_timestamp` 列，这个列作为表的时间索引列，在文件中并不存在。这是因为在创建外部表时，我们没有指定时间索引列，`greptime_timestamp` 列为被自动添加作为时间索引列，并且默认值为 `1970-01-01 00:00:00+0000`。你可以在 [create](../reference/sql/create.md#create-external-table) 文档中查找更多详情。
+在这里，你可能会注意到出现了一个 `greptime_timestamp` 列，这个列作为表的时间索引列，在文件中并不存在。这是因为在创建外部表时，我们没有指定时间索引列，`greptime_timestamp` 列被自动添加作为时间索引列，并且默认值为 `1970-01-01 00:00:00+0000`。你可以在 [create](../reference/sql/create.md#create-external-table) 文档中查找更多详情。
 :::
 
 现在就可以查询外部表了：
@@ -115,5 +115,5 @@ SELECT * FROM yellow_tripdata LIMIT 5;
 ```
 
 :::tip 注意
-查询结果中包含 `greptime_timestamp` 列的值，尽管它在原始文件中并不存在。所有这个列的值均为 `1970-01-01 00:00:00+0000`，这是因为我们在创建外部表时，自动添加列 `greptime_timestamp`，并且默认值为 `1970-01-01 00:00:00+0000`。你可以在 [create](../reference/sql/create.md#create-external-table) 文档中查找更多详情。
+查询结果中包含 `greptime_timestamp` 列的值，尽管它在原始文件中并不存在。这个列的所有值均为 `1970-01-01 00:00:00+0000`，这是因为我们在创建外部表时，自动添加列 `greptime_timestamp`，并且默认值为 `1970-01-01 00:00:00+0000`。你可以在 [create](../reference/sql/create.md#create-external-table) 文档中查找更多详情。
 :::