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Merge pull request #26167 from taosdata/docs/dclow-compress-30 

docs: correct float compression description for 3.0
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wade zhang 2024-06-18 10:27:05 +08:00 committed by GitHub
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12
docs/en/21-tdinternal/08-compress.md
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@ -1,12 +1,8 @@
---
title: Configurable Column Compression
description: Configurable column storage compression method
---
# Configurable Storage Compression
Since TDengine 3.3.0.0, more advanced compression feature is introduced, you can specify compression or not, the compression method and compression level for each column.
## Compression Terminology Definition
@ -34,14 +30,12 @@ In this article, it specifically refers to the level within the secondary compre
| Data Type | Optional Encoding Algorithm | Default Encoding Algorithm | Optional Compression Algorithm|Default Compression Algorithm| Default Compression Level|
| :-----------:|:----------:|:-------:|:-------:|:----------:|:----:|
tinyint/untinyint/smallint/usmallint/int/uint | simple8b| simple8b | lz4/zlib/zstd/xz| lz4 | medium|
| tinyint/untinyint/smallint/usmallint/int/uint | simple8b| simple8b | lz4/zlib/zstd/xz| lz4 | medium|
| bigint/ubigint/timestamp | simple8b/delta-i | delta-i |lz4/zlib/zstd/xz | lz4| medium|
|float/double | delta-d|delta-d |lz4/zlib/zstd/xz/tsz|tsz| medium|
|float/double | delta-d|delta-d |lz4/zlib/zstd/xz/tsz|lz4| medium|
|binary/nchar| disabled| disabled|lz4/zlib/zstd/xz| lz4| medium|
|bool| bit-packing| bit-packing| lz4/zlib/zstd/xz| lz4| medium|
Note: For floating point types, if configured as tsz, its precision is determined by the global configuration of taosd. If configured as tsz, but the lossy compression flag is not configured, lz4 is used for compression by default.
## SQL
### Create Table with Compression
@ -76,7 +70,7 @@ ALTER TABLE [db_name.]tabName MODIFY COLUMN colName [ENCODE 'ecode_type'] [COMPR
- Change the compression method of the column
### View Compression Dethod
### View Compression Method
```sql
DESCRIBE [dbname.]tabName

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docs/zh/21-tdinternal/08-compress.md
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@ -3,8 +3,6 @@ title: 可配置压缩算法
description: 可配置压缩算法
---
# 可配置存储压缩
从 TDengine 3.3.0.0 版本开始，TDengine 提供了更高级的压缩功能，用户可以在建表时针对每一列配置是否进行压缩、以及使用的压缩算法和压缩级别。
## 压缩术语定义
@ -30,16 +28,14 @@ description: 可配置压缩算法
- 各个数据类型的默认压缩算法列表和适用范围
| 数据类型 | 可选编码算法 | 编码算法默认值 | 可选压缩算法|可选压缩算法| 压缩等级默认值|
| 数据类型 | 可选编码算法 | 编码算法默认值 | 可选压缩算法|压缩算法默认值| 压缩等级默认值|
| :-----------:|:----------:|:-------:|:-------:|:----------:|:----:|
tinyint/untinyint/smallint/usmallint/int/uint | simple8b| simple8b | lz4/zlib/zstd/xz| lz4 | medium|
| tinyint/untinyint/smallint/usmallint/int/uint | simple8b| simple8b | lz4/zlib/zstd/xz| lz4 | medium|
| bigint/ubigint/timestamp | simple8b/delta-i | delta-i |lz4/zlib/zstd/xz | lz4| medium|
|float/double | delta-d|delta-d |lz4/zlib/zstd/xz/tsz|tsz| medium|
|float/double | delta-d|delta-d |lz4/zlib/zstd/xz/tsz|lz4| medium|
|binary/nchar| disabled| disabled|lz4/zlib/zstd/xz| lz4| medium|
|bool| bit-packing| bit-packing| lz4/zlib/zstd/xz| lz4| medium|
注意: 针对浮点类型，如果配置为tsz, 其精度由taosd的全局配置决定，如果配置为tsz, 但是没有配置有损压缩标志, 则使用lz4进行压缩
## SQL 语法
### 建表时指定压缩