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The following commit(s) were added to refs/heads/main by this push:
new bc3ef405 fix: adjust TTL description in Operate-Metadata (#1064)
bc3ef405 is described below
commit bc3ef40522cac5b7675e4476d87bbbddad96cf11
Author: leto-b <[email protected]>
AuthorDate: Fri Apr 10 12:10:20 2026 +0800
fix: adjust TTL description in Operate-Metadata (#1064)
---
.../Tree/Basic-Concept/Operate-Metadata_apache.md | 17 ++++++++---------
.../Tree/Basic-Concept/Operate-Metadata_timecho.md | 17 ++++++++---------
.../V1.3.x/Basic-Concept/Operate-Metadata_apache.md | 17 ++++++++---------
.../V1.3.x/Basic-Concept/Operate-Metadata_timecho.md | 17 ++++++++---------
.../dev-1.3/Basic-Concept/Operate-Metadata_apache.md | 17 ++++++++---------
.../dev-1.3/Basic-Concept/Operate-Metadata_timecho.md | 17 ++++++++---------
.../latest/Basic-Concept/Operate-Metadata_apache.md | 17 ++++++++---------
.../latest/Basic-Concept/Operate-Metadata_timecho.md | 17 ++++++++---------
.../Tree/Basic-Concept/Operate-Metadata_apache.md | 16 ++++++++--------
.../Tree/Basic-Concept/Operate-Metadata_timecho.md | 16 ++++++++--------
.../V1.3.x/Basic-Concept/Operate-Metadata_apache.md | 16 ++++++++--------
.../V1.3.x/Basic-Concept/Operate-Metadata_timecho.md | 16 ++++++++--------
.../dev-1.3/Basic-Concept/Operate-Metadata_apache.md | 16 ++++++++--------
.../dev-1.3/Basic-Concept/Operate-Metadata_timecho.md | 16 ++++++++--------
.../latest/Basic-Concept/Operate-Metadata_apache.md | 16 ++++++++--------
.../latest/Basic-Concept/Operate-Metadata_timecho.md | 16 ++++++++--------
16 files changed, 128 insertions(+), 136 deletions(-)
diff --git a/src/UserGuide/Master/Tree/Basic-Concept/Operate-Metadata_apache.md
b/src/UserGuide/Master/Tree/Basic-Concept/Operate-Metadata_apache.md
index 10cf8b1c..da240ffd 100644
--- a/src/UserGuide/Master/Tree/Basic-Concept/Operate-Metadata_apache.md
+++ b/src/UserGuide/Master/Tree/Basic-Concept/Operate-Metadata_apache.md
@@ -244,15 +244,14 @@ The query results in each column are as follows:
### 1.6 TTL
-IoTDB supports device-level TTL settings, which means it is able to delete old
data automatically and periodically. The benefit of using TTL is that hopefully
you can control the total disk space usage and prevent the machine from running
out of disks. Moreover, the query performance may downgrade as the total number
of files goes up and the memory usage also increases as there are more files.
Timely removing such files helps to keep at a high query performance level and
reduce memory usage.
-
-The default unit of TTL is milliseconds. If the time precision in the
configuration file changes to another, the TTL is still set to milliseconds.
-
-When setting TTL, the system will look for all devices included in the set
path and set TTL for these devices. The system will delete expired data at the
device granularity. The expiration check here is based on the data point
timestamp, not the write time.
-After the device data expires, it will not be queryable. The data in the disk
file cannot be guaranteed to be deleted immediately, but it can be guaranteed
to be deleted eventually.
-However, due to operational costs, the expired data will not be physically
deleted right after expiring. The physical deletion is delayed until compaction.
-Therefore, before the data is physically deleted, if the TTL is reduced or
lifted, it may cause data that was previously invisible due to TTL to reappear.
-The system can only set up to 1000 TTL rules, and when this limit is reached,
some TTL rules need to be deleted before new rules can be set.
+IoTDB supports setting data retention time (TTL) at the device level, allowing
the system to automatically and periodically delete old data to effectively
control disk space and maintain high query performance and low memory usage.
TTL is set in milliseconds by default. Once data expires, it cannot be queried
or written, but physical deletion is delayed until compaction. Please note that
changes to TTL may temporarily affect data queryability, and if TTL is reduced
or removed, previously [...]
+
+Important notes:
+- TTL is set in milliseconds and is not affected by the time precision in the
configuration file.
+- Changes to TTL may affect data queryability.
+- The system will eventually remove expired data, but there may be a delay.
+- TTL determines data expiration based on the data point timestamp, not the
ingestion time.
+- The system supports setting up to 1000 TTL rules. When the limit is reached,
existing rules must be removed before new ones can be added.
#### TTL Path Rule
The path can only be prefix paths (i.e., the path cannot contain \* , except
\*\* in the last level).
diff --git
a/src/UserGuide/Master/Tree/Basic-Concept/Operate-Metadata_timecho.md
b/src/UserGuide/Master/Tree/Basic-Concept/Operate-Metadata_timecho.md
index 4be56beb..864a54c8 100644
--- a/src/UserGuide/Master/Tree/Basic-Concept/Operate-Metadata_timecho.md
+++ b/src/UserGuide/Master/Tree/Basic-Concept/Operate-Metadata_timecho.md
@@ -246,15 +246,14 @@ The query results in each column are as follows:
### 1.6 TTL
-IoTDB supports device-level TTL settings, which means it is able to delete old
data automatically and periodically. The benefit of using TTL is that hopefully
you can control the total disk space usage and prevent the machine from running
out of disks. Moreover, the query performance may downgrade as the total number
of files goes up and the memory usage also increases as there are more files.
Timely removing such files helps to keep at a high query performance level and
reduce memory usage.
-
-The default unit of TTL is milliseconds. If the time precision in the
configuration file changes to another, the TTL is still set to milliseconds.
-
-When setting TTL, the system will look for all devices included in the set
path and set TTL for these devices. The system will delete expired data at the
device granularity. The expiration check here is based on the data point
timestamp, not the write time.
-After the device data expires, it will not be queryable. The data in the disk
file cannot be guaranteed to be deleted immediately, but it can be guaranteed
to be deleted eventually.
-However, due to operational costs, the expired data will not be physically
deleted right after expiring. The physical deletion is delayed until compaction.
-Therefore, before the data is physically deleted, if the TTL is reduced or
lifted, it may cause data that was previously invisible due to TTL to reappear.
-The system can only set up to 1000 TTL rules, and when this limit is reached,
some TTL rules need to be deleted before new rules can be set.
+IoTDB supports setting data retention time (TTL) at the device level, allowing
the system to automatically and periodically delete old data to effectively
control disk space and maintain high query performance and low memory usage.
TTL is set in milliseconds by default. Once data expires, it cannot be queried
or written, but physical deletion is delayed until compaction. Please note that
changes to TTL may temporarily affect data queryability, and if TTL is reduced
or removed, previously [...]
+
+Important notes:
+- TTL is set in milliseconds and is not affected by the time precision in the
configuration file.
+- Changes to TTL may affect data queryability.
+- The system will eventually remove expired data, but there may be a delay.
+- TTL determines data expiration based on the data point timestamp, not the
ingestion time.
+- The system supports setting up to 1000 TTL rules. When the limit is reached,
existing rules must be removed before new ones can be added.
#### TTL Path Rule
The path can only be prefix paths (i.e., the path cannot contain \* , except
\*\* in the last level).
diff --git a/src/UserGuide/V1.3.x/Basic-Concept/Operate-Metadata_apache.md
b/src/UserGuide/V1.3.x/Basic-Concept/Operate-Metadata_apache.md
index 9b9185dc..ee5d4535 100644
--- a/src/UserGuide/V1.3.x/Basic-Concept/Operate-Metadata_apache.md
+++ b/src/UserGuide/V1.3.x/Basic-Concept/Operate-Metadata_apache.md
@@ -244,15 +244,14 @@ The query results in each column are as follows:
### TTL
-IoTDB supports device-level TTL settings, which means it is able to delete old
data automatically and periodically. The benefit of using TTL is that hopefully
you can control the total disk space usage and prevent the machine from running
out of disks. Moreover, the query performance may downgrade as the total number
of files goes up and the memory usage also increases as there are more files.
Timely removing such files helps to keep at a high query performance level and
reduce memory usage.
-
-The default unit of TTL is milliseconds. If the time precision in the
configuration file changes to another, the TTL is still set to milliseconds.
-
-When setting TTL, the system will look for all devices included in the set
path and set TTL for these devices. The system will delete expired data at the
device granularity. The expiration check here is based on the data point
timestamp, not the write time.
-After the device data expires, it will not be queryable. The data in the disk
file cannot be guaranteed to be deleted immediately, but it can be guaranteed
to be deleted eventually.
-However, due to operational costs, the expired data will not be physically
deleted right after expiring. The physical deletion is delayed until compaction.
-Therefore, before the data is physically deleted, if the TTL is reduced or
lifted, it may cause data that was previously invisible due to TTL to reappear.
-The system can only set up to 1000 TTL rules, and when this limit is reached,
some TTL rules need to be deleted before new rules can be set.
+IoTDB supports setting data retention time (TTL) at the device level, allowing
the system to automatically and periodically delete old data to effectively
control disk space and maintain high query performance and low memory usage.
TTL is set in milliseconds by default. Once data expires, it cannot be queried
or written, but physical deletion is delayed until compaction. Please note that
changes to TTL may temporarily affect data queryability, and if TTL is reduced
or removed, previously [...]
+
+Important notes:
+- TTL is set in milliseconds and is not affected by the time precision in the
configuration file.
+- Changes to TTL may affect data queryability.
+- The system will eventually remove expired data, but there may be a delay.
+- TTL determines data expiration based on the data point timestamp, not the
ingestion time.
+- The system supports setting up to 1000 TTL rules. When the limit is reached,
existing rules must be removed before new ones can be added.
#### TTL Path Rule
The path can only be prefix paths (i.e., the path cannot contain \* , except
\*\* in the last level).
diff --git a/src/UserGuide/V1.3.x/Basic-Concept/Operate-Metadata_timecho.md
b/src/UserGuide/V1.3.x/Basic-Concept/Operate-Metadata_timecho.md
index af23e2d4..4522df58 100644
--- a/src/UserGuide/V1.3.x/Basic-Concept/Operate-Metadata_timecho.md
+++ b/src/UserGuide/V1.3.x/Basic-Concept/Operate-Metadata_timecho.md
@@ -244,15 +244,14 @@ The query results in each column are as follows:
### TTL
-IoTDB supports device-level TTL settings, which means it is able to delete old
data automatically and periodically. The benefit of using TTL is that hopefully
you can control the total disk space usage and prevent the machine from running
out of disks. Moreover, the query performance may downgrade as the total number
of files goes up and the memory usage also increases as there are more files.
Timely removing such files helps to keep at a high query performance level and
reduce memory usage.
-
-The default unit of TTL is milliseconds. If the time precision in the
configuration file changes to another, the TTL is still set to milliseconds.
-
-When setting TTL, the system will look for all devices included in the set
path and set TTL for these devices. The system will delete expired data at the
device granularity. The expiration check here is based on the data point
timestamp, not the write time.
-After the device data expires, it will not be queryable. The data in the disk
file cannot be guaranteed to be deleted immediately, but it can be guaranteed
to be deleted eventually.
-However, due to operational costs, the expired data will not be physically
deleted right after expiring. The physical deletion is delayed until compaction.
-Therefore, before the data is physically deleted, if the TTL is reduced or
lifted, it may cause data that was previously invisible due to TTL to reappear.
-The system can only set up to 1000 TTL rules, and when this limit is reached,
some TTL rules need to be deleted before new rules can be set.
+IoTDB supports setting data retention time (TTL) at the device level, allowing
the system to automatically and periodically delete old data to effectively
control disk space and maintain high query performance and low memory usage.
TTL is set in milliseconds by default. Once data expires, it cannot be queried
or written, but physical deletion is delayed until compaction. Please note that
changes to TTL may temporarily affect data queryability, and if TTL is reduced
or removed, previously [...]
+
+Important notes:
+- TTL is set in milliseconds and is not affected by the time precision in the
configuration file.
+- Changes to TTL may affect data queryability.
+- The system will eventually remove expired data, but there may be a delay.
+- TTL determines data expiration based on the data point timestamp, not the
ingestion time.
+- The system supports setting up to 1000 TTL rules. When the limit is reached,
existing rules must be removed before new ones can be added.
#### TTL Path Rule
The path can only be prefix paths (i.e., the path cannot contain \* , except
\*\* in the last level).
diff --git a/src/UserGuide/dev-1.3/Basic-Concept/Operate-Metadata_apache.md
b/src/UserGuide/dev-1.3/Basic-Concept/Operate-Metadata_apache.md
index c9a6065a..7a655cc9 100644
--- a/src/UserGuide/dev-1.3/Basic-Concept/Operate-Metadata_apache.md
+++ b/src/UserGuide/dev-1.3/Basic-Concept/Operate-Metadata_apache.md
@@ -244,15 +244,14 @@ The query results in each column are as follows:
### TTL
-IoTDB supports device-level TTL settings, which means it is able to delete old
data automatically and periodically. The benefit of using TTL is that hopefully
you can control the total disk space usage and prevent the machine from running
out of disks. Moreover, the query performance may downgrade as the total number
of files goes up and the memory usage also increases as there are more files.
Timely removing such files helps to keep at a high query performance level and
reduce memory usage.
-
-The default unit of TTL is milliseconds. If the time precision in the
configuration file changes to another, the TTL is still set to milliseconds.
-
-When setting TTL, the system will look for all devices included in the set
path and set TTL for these devices. The system will delete expired data at the
device granularity. The expiration check here is based on the data point
timestamp, not the write time.
-After the device data expires, it will not be queryable. The data in the disk
file cannot be guaranteed to be deleted immediately, but it can be guaranteed
to be deleted eventually.
-However, due to operational costs, the expired data will not be physically
deleted right after expiring. The physical deletion is delayed until compaction.
-Therefore, before the data is physically deleted, if the TTL is reduced or
lifted, it may cause data that was previously invisible due to TTL to reappear.
-The system can only set up to 1000 TTL rules, and when this limit is reached,
some TTL rules need to be deleted before new rules can be set.
+IoTDB supports setting data retention time (TTL) at the device level, allowing
the system to automatically and periodically delete old data to effectively
control disk space and maintain high query performance and low memory usage.
TTL is set in milliseconds by default. Once data expires, it cannot be queried
or written, but physical deletion is delayed until compaction. Please note that
changes to TTL may temporarily affect data queryability, and if TTL is reduced
or removed, previously [...]
+
+Important notes:
+- TTL is set in milliseconds and is not affected by the time precision in the
configuration file.
+- Changes to TTL may affect data queryability.
+- The system will eventually remove expired data, but there may be a delay.
+- TTL determines data expiration based on the data point timestamp, not the
ingestion time.
+- The system supports setting up to 1000 TTL rules. When the limit is reached,
existing rules must be removed before new ones can be added.
#### TTL Path Rule
The path can only be prefix paths (i.e., the path cannot contain \* , except
\*\* in the last level).
diff --git a/src/UserGuide/dev-1.3/Basic-Concept/Operate-Metadata_timecho.md
b/src/UserGuide/dev-1.3/Basic-Concept/Operate-Metadata_timecho.md
index af23e2d4..4522df58 100644
--- a/src/UserGuide/dev-1.3/Basic-Concept/Operate-Metadata_timecho.md
+++ b/src/UserGuide/dev-1.3/Basic-Concept/Operate-Metadata_timecho.md
@@ -244,15 +244,14 @@ The query results in each column are as follows:
### TTL
-IoTDB supports device-level TTL settings, which means it is able to delete old
data automatically and periodically. The benefit of using TTL is that hopefully
you can control the total disk space usage and prevent the machine from running
out of disks. Moreover, the query performance may downgrade as the total number
of files goes up and the memory usage also increases as there are more files.
Timely removing such files helps to keep at a high query performance level and
reduce memory usage.
-
-The default unit of TTL is milliseconds. If the time precision in the
configuration file changes to another, the TTL is still set to milliseconds.
-
-When setting TTL, the system will look for all devices included in the set
path and set TTL for these devices. The system will delete expired data at the
device granularity. The expiration check here is based on the data point
timestamp, not the write time.
-After the device data expires, it will not be queryable. The data in the disk
file cannot be guaranteed to be deleted immediately, but it can be guaranteed
to be deleted eventually.
-However, due to operational costs, the expired data will not be physically
deleted right after expiring. The physical deletion is delayed until compaction.
-Therefore, before the data is physically deleted, if the TTL is reduced or
lifted, it may cause data that was previously invisible due to TTL to reappear.
-The system can only set up to 1000 TTL rules, and when this limit is reached,
some TTL rules need to be deleted before new rules can be set.
+IoTDB supports setting data retention time (TTL) at the device level, allowing
the system to automatically and periodically delete old data to effectively
control disk space and maintain high query performance and low memory usage.
TTL is set in milliseconds by default. Once data expires, it cannot be queried
or written, but physical deletion is delayed until compaction. Please note that
changes to TTL may temporarily affect data queryability, and if TTL is reduced
or removed, previously [...]
+
+Important notes:
+- TTL is set in milliseconds and is not affected by the time precision in the
configuration file.
+- Changes to TTL may affect data queryability.
+- The system will eventually remove expired data, but there may be a delay.
+- TTL determines data expiration based on the data point timestamp, not the
ingestion time.
+- The system supports setting up to 1000 TTL rules. When the limit is reached,
existing rules must be removed before new ones can be added.
#### TTL Path Rule
The path can only be prefix paths (i.e., the path cannot contain \* , except
\*\* in the last level).
diff --git a/src/UserGuide/latest/Basic-Concept/Operate-Metadata_apache.md
b/src/UserGuide/latest/Basic-Concept/Operate-Metadata_apache.md
index 10cf8b1c..da240ffd 100644
--- a/src/UserGuide/latest/Basic-Concept/Operate-Metadata_apache.md
+++ b/src/UserGuide/latest/Basic-Concept/Operate-Metadata_apache.md
@@ -244,15 +244,14 @@ The query results in each column are as follows:
### 1.6 TTL
-IoTDB supports device-level TTL settings, which means it is able to delete old
data automatically and periodically. The benefit of using TTL is that hopefully
you can control the total disk space usage and prevent the machine from running
out of disks. Moreover, the query performance may downgrade as the total number
of files goes up and the memory usage also increases as there are more files.
Timely removing such files helps to keep at a high query performance level and
reduce memory usage.
-
-The default unit of TTL is milliseconds. If the time precision in the
configuration file changes to another, the TTL is still set to milliseconds.
-
-When setting TTL, the system will look for all devices included in the set
path and set TTL for these devices. The system will delete expired data at the
device granularity. The expiration check here is based on the data point
timestamp, not the write time.
-After the device data expires, it will not be queryable. The data in the disk
file cannot be guaranteed to be deleted immediately, but it can be guaranteed
to be deleted eventually.
-However, due to operational costs, the expired data will not be physically
deleted right after expiring. The physical deletion is delayed until compaction.
-Therefore, before the data is physically deleted, if the TTL is reduced or
lifted, it may cause data that was previously invisible due to TTL to reappear.
-The system can only set up to 1000 TTL rules, and when this limit is reached,
some TTL rules need to be deleted before new rules can be set.
+IoTDB supports setting data retention time (TTL) at the device level, allowing
the system to automatically and periodically delete old data to effectively
control disk space and maintain high query performance and low memory usage.
TTL is set in milliseconds by default. Once data expires, it cannot be queried
or written, but physical deletion is delayed until compaction. Please note that
changes to TTL may temporarily affect data queryability, and if TTL is reduced
or removed, previously [...]
+
+Important notes:
+- TTL is set in milliseconds and is not affected by the time precision in the
configuration file.
+- Changes to TTL may affect data queryability.
+- The system will eventually remove expired data, but there may be a delay.
+- TTL determines data expiration based on the data point timestamp, not the
ingestion time.
+- The system supports setting up to 1000 TTL rules. When the limit is reached,
existing rules must be removed before new ones can be added.
#### TTL Path Rule
The path can only be prefix paths (i.e., the path cannot contain \* , except
\*\* in the last level).
diff --git a/src/UserGuide/latest/Basic-Concept/Operate-Metadata_timecho.md
b/src/UserGuide/latest/Basic-Concept/Operate-Metadata_timecho.md
index 4be56beb..864a54c8 100644
--- a/src/UserGuide/latest/Basic-Concept/Operate-Metadata_timecho.md
+++ b/src/UserGuide/latest/Basic-Concept/Operate-Metadata_timecho.md
@@ -246,15 +246,14 @@ The query results in each column are as follows:
### 1.6 TTL
-IoTDB supports device-level TTL settings, which means it is able to delete old
data automatically and periodically. The benefit of using TTL is that hopefully
you can control the total disk space usage and prevent the machine from running
out of disks. Moreover, the query performance may downgrade as the total number
of files goes up and the memory usage also increases as there are more files.
Timely removing such files helps to keep at a high query performance level and
reduce memory usage.
-
-The default unit of TTL is milliseconds. If the time precision in the
configuration file changes to another, the TTL is still set to milliseconds.
-
-When setting TTL, the system will look for all devices included in the set
path and set TTL for these devices. The system will delete expired data at the
device granularity. The expiration check here is based on the data point
timestamp, not the write time.
-After the device data expires, it will not be queryable. The data in the disk
file cannot be guaranteed to be deleted immediately, but it can be guaranteed
to be deleted eventually.
-However, due to operational costs, the expired data will not be physically
deleted right after expiring. The physical deletion is delayed until compaction.
-Therefore, before the data is physically deleted, if the TTL is reduced or
lifted, it may cause data that was previously invisible due to TTL to reappear.
-The system can only set up to 1000 TTL rules, and when this limit is reached,
some TTL rules need to be deleted before new rules can be set.
+IoTDB supports setting data retention time (TTL) at the device level, allowing
the system to automatically and periodically delete old data to effectively
control disk space and maintain high query performance and low memory usage.
TTL is set in milliseconds by default. Once data expires, it cannot be queried
or written, but physical deletion is delayed until compaction. Please note that
changes to TTL may temporarily affect data queryability, and if TTL is reduced
or removed, previously [...]
+
+Important notes:
+- TTL is set in milliseconds and is not affected by the time precision in the
configuration file.
+- Changes to TTL may affect data queryability.
+- The system will eventually remove expired data, but there may be a delay.
+- TTL determines data expiration based on the data point timestamp, not the
ingestion time.
+- The system supports setting up to 1000 TTL rules. When the limit is reached,
existing rules must be removed before new ones can be added.
#### TTL Path Rule
The path can only be prefix paths (i.e., the path cannot contain \* , except
\*\* in the last level).
diff --git
a/src/zh/UserGuide/Master/Tree/Basic-Concept/Operate-Metadata_apache.md
b/src/zh/UserGuide/Master/Tree/Basic-Concept/Operate-Metadata_apache.md
index 720669e6..7d3cc162 100644
--- a/src/zh/UserGuide/Master/Tree/Basic-Concept/Operate-Metadata_apache.md
+++ b/src/zh/UserGuide/Master/Tree/Basic-Concept/Operate-Metadata_apache.md
@@ -148,14 +148,14 @@ It costs 0.002s
### 1.5 数据保留时间（TTL）
-IoTDB 支持对 device 级别设置数据保留时间（TTL），这使得 IoTDB 可以定期、自动地删除一定时间之前的数据。合理使用 TTL可以帮助您控制
IoTDB
占用的总磁盘空间以避免出现磁盘写满等异常。并且，随着文件数量的增多，查询性能往往随之下降，内存占用也会有所提高。及时地删除一些较老的文件有助于使查询性能维持在一个较高的水平和减少内存资源的占用。
-
-TTL的默认单位为毫秒，如果配置文件中的时间精度修改为其他单位，设置ttl时仍然使用毫秒单位。
-
-当设置 TTL 时，系统会根据设置的路径寻找所包含的所有 device，并为这些 device 设置 TTL
时间，系统会按设备粒度对过期数据进行删除。请注意，此处是否过期判断依据的是数据点时间，不是写入时间。
-当设备数据过期后，将不能被查询到，但磁盘文件中的数据不能保证立即删除（会在一定时间内删除），但可以保证最终被删除。
-考虑到操作代价，系统不会立即物理删除超过 TTL 的数据，而是通过合并来延迟地物理删除。因此，在数据被物理删除前，如果调小或者解除 TTL，可能会导致之前因
TTL 而不可见的数据重新出现。
-系统中仅能设置至多 1000 条 TTL 规则，达到该上限时，需要先删除部分 TTL 规则才能设置新的规则
+IoTDB 支持对设备（device）级别设置数据保留时间（TTL），允许系统自动定期删除旧数据，以有效控制磁盘空间并维护高性能查询和低内存占用。TTL
默认以毫秒为单位，数据过期后不可查询且禁止写入，但物理删除会延迟至压缩时。需注意，TTL 变更可能导致短暂数据可查询性变化，且若调小或解除 TTL，之前因
TTL 不可见的数据可能重新出现。
+
+注意事项：
+- TTL 设置为毫秒，不受配置文件时间精度影响。
+- TTL 变更可能影响数据的可查询性。
+- 系统最终会移除过期数据，但存在延迟。
+- TTL 判断数据是否过期依据的是数据点时间，非写入时间。
+- 系统最多支持设置 1000 条 TTL 规则，达到上限需先删除部分规则才能设置新规则。
#### TTL Path 规则
设置的路径 path 只支持前缀路径（即路径中间不能带 \* ， 且必须以 \*\* 结尾），该路径会匹配到设备，也允许用户指定不带星的 path 为具体的
database 或 device，当 path 不带 \* 时，会检查是否匹配到 database，若匹配到 database，则会同时设置 path 和
path.\*\*。
diff --git
a/src/zh/UserGuide/Master/Tree/Basic-Concept/Operate-Metadata_timecho.md
b/src/zh/UserGuide/Master/Tree/Basic-Concept/Operate-Metadata_timecho.md
index a9335e01..d51bd853 100644
--- a/src/zh/UserGuide/Master/Tree/Basic-Concept/Operate-Metadata_timecho.md
+++ b/src/zh/UserGuide/Master/Tree/Basic-Concept/Operate-Metadata_timecho.md
@@ -147,14 +147,14 @@ It costs 0.002s
### 1.5 数据保留时间（TTL）
-IoTDB 支持对 device 级别设置数据保留时间（TTL），这使得 IoTDB 可以定期、自动地删除一定时间之前的数据。合理使用 TTL可以帮助您控制
IoTDB
占用的总磁盘空间以避免出现磁盘写满等异常。并且，随着文件数量的增多，查询性能往往随之下降，内存占用也会有所提高。及时地删除一些较老的文件有助于使查询性能维持在一个较高的水平和减少内存资源的占用。
-
-TTL的默认单位为毫秒，如果配置文件中的时间精度修改为其他单位，设置ttl时仍然使用毫秒单位。
-
-当设置 TTL 时，系统会根据设置的路径寻找所包含的所有 device，并为这些 device 设置 TTL
时间，系统会按设备粒度对过期数据进行删除。请注意，此处是否过期判断依据的是数据点时间，不是写入时间。
-当设备数据过期后，将不能被查询到，但磁盘文件中的数据不能保证立即删除（会在一定时间内删除），但可以保证最终被删除。
-考虑到操作代价，系统不会立即物理删除超过 TTL 的数据，而是通过合并来延迟地物理删除。因此，在数据被物理删除前，如果调小或者解除 TTL，可能会导致之前因
TTL 而不可见的数据重新出现。
-系统中仅能设置至多 1000 条 TTL 规则，达到该上限时，需要先删除部分 TTL 规则才能设置新的规则
+IoTDB 支持对设备（device）级别设置数据保留时间（TTL），允许系统自动定期删除旧数据，以有效控制磁盘空间并维护高性能查询和低内存占用。TTL
默认以毫秒为单位，数据过期后不可查询且禁止写入，但物理删除会延迟至压缩时。需注意，TTL 变更可能导致短暂数据可查询性变化，且若调小或解除 TTL，之前因
TTL 不可见的数据可能重新出现。
+
+注意事项：
+- TTL 设置为毫秒，不受配置文件时间精度影响。
+- TTL 变更可能影响数据的可查询性。
+- 系统最终会移除过期数据，但存在延迟。
+- TTL 判断数据是否过期依据的是数据点时间，非写入时间。
+- 系统最多支持设置 1000 条 TTL 规则，达到上限需先删除部分规则才能设置新规则。
#### TTL Path 规则
设置的路径 path 只支持前缀路径（即路径中间不能带 \* ， 且必须以 \*\* 结尾），该路径会匹配到设备，也允许用户指定不带星的 path 为具体的
database 或 device，当 path 不带 \* 时，会检查是否匹配到 database，若匹配到 database，则会同时设置 path 和
path.\*\*。
diff --git a/src/zh/UserGuide/V1.3.x/Basic-Concept/Operate-Metadata_apache.md
b/src/zh/UserGuide/V1.3.x/Basic-Concept/Operate-Metadata_apache.md
index ebc6a423..f6d8cb6e 100644
--- a/src/zh/UserGuide/V1.3.x/Basic-Concept/Operate-Metadata_apache.md
+++ b/src/zh/UserGuide/V1.3.x/Basic-Concept/Operate-Metadata_apache.md
@@ -147,14 +147,14 @@ It costs 0.002s
### 数据保留时间（TTL）
-IoTDB 支持对 device 级别设置数据保留时间（TTL），这使得 IoTDB 可以定期、自动地删除一定时间之前的数据。合理使用 TTL可以帮助您控制
IoTDB
占用的总磁盘空间以避免出现磁盘写满等异常。并且，随着文件数量的增多，查询性能往往随之下降，内存占用也会有所提高。及时地删除一些较老的文件有助于使查询性能维持在一个较高的水平和减少内存资源的占用。
-
-TTL的默认单位为毫秒，如果配置文件中的时间精度修改为其他单位，设置ttl时仍然使用毫秒单位。
-
-当设置 TTL 时，系统会根据设置的路径寻找所包含的所有 device，并为这些 device 设置 TTL
时间，系统会按设备粒度对过期数据进行删除。请注意，此处是否过期判断依据的是数据点时间，不是写入时间。
-当设备数据过期后，将不能被查询到，但磁盘文件中的数据不能保证立即删除（会在一定时间内删除），但可以保证最终被删除。
-考虑到操作代价，系统不会立即物理删除超过 TTL 的数据，而是通过合并来延迟地物理删除。因此，在数据被物理删除前，如果调小或者解除 TTL，可能会导致之前因
TTL 而不可见的数据重新出现。
-系统中仅能设置至多 1000 条 TTL 规则，达到该上限时，需要先删除部分 TTL 规则才能设置新的规则
+IoTDB 支持对设备（device）级别设置数据保留时间（TTL），允许系统自动定期删除旧数据，以有效控制磁盘空间并维护高性能查询和低内存占用。TTL
默认以毫秒为单位，数据过期后不可查询且禁止写入，但物理删除会延迟至压缩时。需注意，TTL 变更可能导致短暂数据可查询性变化，且若调小或解除 TTL，之前因
TTL 不可见的数据可能重新出现。
+
+注意事项：
+- TTL 设置为毫秒，不受配置文件时间精度影响。
+- TTL 变更可能影响数据的可查询性。
+- 系统最终会移除过期数据，但存在延迟。
+- TTL 判断数据是否过期依据的是数据点时间，非写入时间。
+- 系统最多支持设置 1000 条 TTL 规则，达到上限需先删除部分规则才能设置新规则。
#### TTL Path 规则
设置的路径 path 只支持前缀路径（即路径中间不能带 \* ， 且必须以 \*\* 结尾），该路径会匹配到设备，也允许用户指定不带星的 path 为具体的
database 或 device，当 path 不带 \* 时，会检查是否匹配到 database，若匹配到 database，则会同时设置 path 和
path.\*\*。
diff --git a/src/zh/UserGuide/V1.3.x/Basic-Concept/Operate-Metadata_timecho.md
b/src/zh/UserGuide/V1.3.x/Basic-Concept/Operate-Metadata_timecho.md
index 46439f87..133e5748 100644
--- a/src/zh/UserGuide/V1.3.x/Basic-Concept/Operate-Metadata_timecho.md
+++ b/src/zh/UserGuide/V1.3.x/Basic-Concept/Operate-Metadata_timecho.md
@@ -146,14 +146,14 @@ It costs 0.002s
### 数据保留时间（TTL）
-IoTDB 支持对 device 级别设置数据保留时间（TTL），这使得 IoTDB 可以定期、自动地删除一定时间之前的数据。合理使用 TTL
可以帮助您控制 IoTDB
占用的总磁盘空间以避免出现磁盘写满等异常。并且，随着文件数量的增多，查询性能往往随之下降，内存占用也会有所提高。及时地删除一些较老的文件有助于使查询性能维持在一个较高的水平和减少内存资源的占用。
-
-TTL的默认单位为毫秒，如果配置文件中的时间精度修改为其他单位，设置ttl时仍然使用毫秒单位。
-
-当设置 TTL 时，系统会根据设置的路径寻找所包含的所有 device，并为这些 device 设置 TTL
时间，系统会按设备粒度对过期数据进行删除。请注意，此处是否过期判断依据的是数据点时间，不是写入时间。
-当设备数据过期后，将不能被查询到，但磁盘文件中的数据不能保证立即删除（会在一定时间内删除），但可以保证最终被删除。
-考虑到操作代价，系统不会立即物理删除超过 TTL 的数据，而是通过合并来延迟地物理删除。因此，在数据被物理删除前，如果调小或者解除 TTL，可能会导致之前因
TTL 而不可见的数据重新出现。
-系统中仅能设置至多 1000 条 TTL 规则，达到该上限时，需要先删除部分 TTL 规则才能设置新的规则
+IoTDB 支持对设备（device）级别设置数据保留时间（TTL），允许系统自动定期删除旧数据，以有效控制磁盘空间并维护高性能查询和低内存占用。TTL
默认以毫秒为单位，数据过期后不可查询且禁止写入，但物理删除会延迟至压缩时。需注意，TTL 变更可能导致短暂数据可查询性变化，且若调小或解除 TTL，之前因
TTL 不可见的数据可能重新出现。
+
+注意事项：
+- TTL 设置为毫秒，不受配置文件时间精度影响。
+- TTL 变更可能影响数据的可查询性。
+- 系统最终会移除过期数据，但存在延迟。
+- TTL 判断数据是否过期依据的是数据点时间，非写入时间。
+- 系统最多支持设置 1000 条 TTL 规则，达到上限需先删除部分规则才能设置新规则。
#### TTL Path 规则
设置的路径 path 只支持前缀路径（即路径中间不能带 \* ， 且必须以 \*\* 结尾），该路径会匹配到设备，也允许用户指定不带星的 path 为具体的
database 或 device，当 path 不带 \* 时，会检查是否匹配到 database，若匹配到 database，则会同时设置 path 和
path.\*\*。
diff --git a/src/zh/UserGuide/dev-1.3/Basic-Concept/Operate-Metadata_apache.md
b/src/zh/UserGuide/dev-1.3/Basic-Concept/Operate-Metadata_apache.md
index ebc6a423..f6d8cb6e 100644
--- a/src/zh/UserGuide/dev-1.3/Basic-Concept/Operate-Metadata_apache.md
+++ b/src/zh/UserGuide/dev-1.3/Basic-Concept/Operate-Metadata_apache.md
@@ -147,14 +147,14 @@ It costs 0.002s
### 数据保留时间（TTL）
-IoTDB 支持对 device 级别设置数据保留时间（TTL），这使得 IoTDB 可以定期、自动地删除一定时间之前的数据。合理使用 TTL可以帮助您控制
IoTDB
占用的总磁盘空间以避免出现磁盘写满等异常。并且，随着文件数量的增多，查询性能往往随之下降，内存占用也会有所提高。及时地删除一些较老的文件有助于使查询性能维持在一个较高的水平和减少内存资源的占用。
-
-TTL的默认单位为毫秒，如果配置文件中的时间精度修改为其他单位，设置ttl时仍然使用毫秒单位。
-
-当设置 TTL 时，系统会根据设置的路径寻找所包含的所有 device，并为这些 device 设置 TTL
时间，系统会按设备粒度对过期数据进行删除。请注意，此处是否过期判断依据的是数据点时间，不是写入时间。
-当设备数据过期后，将不能被查询到，但磁盘文件中的数据不能保证立即删除（会在一定时间内删除），但可以保证最终被删除。
-考虑到操作代价，系统不会立即物理删除超过 TTL 的数据，而是通过合并来延迟地物理删除。因此，在数据被物理删除前，如果调小或者解除 TTL，可能会导致之前因
TTL 而不可见的数据重新出现。
-系统中仅能设置至多 1000 条 TTL 规则，达到该上限时，需要先删除部分 TTL 规则才能设置新的规则
+IoTDB 支持对设备（device）级别设置数据保留时间（TTL），允许系统自动定期删除旧数据，以有效控制磁盘空间并维护高性能查询和低内存占用。TTL
默认以毫秒为单位，数据过期后不可查询且禁止写入，但物理删除会延迟至压缩时。需注意，TTL 变更可能导致短暂数据可查询性变化，且若调小或解除 TTL，之前因
TTL 不可见的数据可能重新出现。
+
+注意事项：
+- TTL 设置为毫秒，不受配置文件时间精度影响。
+- TTL 变更可能影响数据的可查询性。
+- 系统最终会移除过期数据，但存在延迟。
+- TTL 判断数据是否过期依据的是数据点时间，非写入时间。
+- 系统最多支持设置 1000 条 TTL 规则，达到上限需先删除部分规则才能设置新规则。
#### TTL Path 规则
设置的路径 path 只支持前缀路径（即路径中间不能带 \* ， 且必须以 \*\* 结尾），该路径会匹配到设备，也允许用户指定不带星的 path 为具体的
database 或 device，当 path 不带 \* 时，会检查是否匹配到 database，若匹配到 database，则会同时设置 path 和
path.\*\*。
diff --git a/src/zh/UserGuide/dev-1.3/Basic-Concept/Operate-Metadata_timecho.md
b/src/zh/UserGuide/dev-1.3/Basic-Concept/Operate-Metadata_timecho.md
index 46439f87..133e5748 100644
--- a/src/zh/UserGuide/dev-1.3/Basic-Concept/Operate-Metadata_timecho.md
+++ b/src/zh/UserGuide/dev-1.3/Basic-Concept/Operate-Metadata_timecho.md
@@ -146,14 +146,14 @@ It costs 0.002s
### 数据保留时间（TTL）
-IoTDB 支持对 device 级别设置数据保留时间（TTL），这使得 IoTDB 可以定期、自动地删除一定时间之前的数据。合理使用 TTL
可以帮助您控制 IoTDB
占用的总磁盘空间以避免出现磁盘写满等异常。并且，随着文件数量的增多，查询性能往往随之下降，内存占用也会有所提高。及时地删除一些较老的文件有助于使查询性能维持在一个较高的水平和减少内存资源的占用。
-
-TTL的默认单位为毫秒，如果配置文件中的时间精度修改为其他单位，设置ttl时仍然使用毫秒单位。
-
-当设置 TTL 时，系统会根据设置的路径寻找所包含的所有 device，并为这些 device 设置 TTL
时间，系统会按设备粒度对过期数据进行删除。请注意，此处是否过期判断依据的是数据点时间，不是写入时间。
-当设备数据过期后，将不能被查询到，但磁盘文件中的数据不能保证立即删除（会在一定时间内删除），但可以保证最终被删除。
-考虑到操作代价，系统不会立即物理删除超过 TTL 的数据，而是通过合并来延迟地物理删除。因此，在数据被物理删除前，如果调小或者解除 TTL，可能会导致之前因
TTL 而不可见的数据重新出现。
-系统中仅能设置至多 1000 条 TTL 规则，达到该上限时，需要先删除部分 TTL 规则才能设置新的规则
+IoTDB 支持对设备（device）级别设置数据保留时间（TTL），允许系统自动定期删除旧数据，以有效控制磁盘空间并维护高性能查询和低内存占用。TTL
默认以毫秒为单位，数据过期后不可查询且禁止写入，但物理删除会延迟至压缩时。需注意，TTL 变更可能导致短暂数据可查询性变化，且若调小或解除 TTL，之前因
TTL 不可见的数据可能重新出现。
+
+注意事项：
+- TTL 设置为毫秒，不受配置文件时间精度影响。
+- TTL 变更可能影响数据的可查询性。
+- 系统最终会移除过期数据，但存在延迟。
+- TTL 判断数据是否过期依据的是数据点时间，非写入时间。
+- 系统最多支持设置 1000 条 TTL 规则，达到上限需先删除部分规则才能设置新规则。
#### TTL Path 规则
设置的路径 path 只支持前缀路径（即路径中间不能带 \* ， 且必须以 \*\* 结尾），该路径会匹配到设备，也允许用户指定不带星的 path 为具体的
database 或 device，当 path 不带 \* 时，会检查是否匹配到 database，若匹配到 database，则会同时设置 path 和
path.\*\*。
diff --git a/src/zh/UserGuide/latest/Basic-Concept/Operate-Metadata_apache.md
b/src/zh/UserGuide/latest/Basic-Concept/Operate-Metadata_apache.md
index 720669e6..7d3cc162 100644
--- a/src/zh/UserGuide/latest/Basic-Concept/Operate-Metadata_apache.md
+++ b/src/zh/UserGuide/latest/Basic-Concept/Operate-Metadata_apache.md
@@ -148,14 +148,14 @@ It costs 0.002s
### 1.5 数据保留时间（TTL）
-IoTDB 支持对 device 级别设置数据保留时间（TTL），这使得 IoTDB 可以定期、自动地删除一定时间之前的数据。合理使用 TTL可以帮助您控制
IoTDB
占用的总磁盘空间以避免出现磁盘写满等异常。并且，随着文件数量的增多，查询性能往往随之下降，内存占用也会有所提高。及时地删除一些较老的文件有助于使查询性能维持在一个较高的水平和减少内存资源的占用。
-
-TTL的默认单位为毫秒，如果配置文件中的时间精度修改为其他单位，设置ttl时仍然使用毫秒单位。
-
-当设置 TTL 时，系统会根据设置的路径寻找所包含的所有 device，并为这些 device 设置 TTL
时间，系统会按设备粒度对过期数据进行删除。请注意，此处是否过期判断依据的是数据点时间，不是写入时间。
-当设备数据过期后，将不能被查询到，但磁盘文件中的数据不能保证立即删除（会在一定时间内删除），但可以保证最终被删除。
-考虑到操作代价，系统不会立即物理删除超过 TTL 的数据，而是通过合并来延迟地物理删除。因此，在数据被物理删除前，如果调小或者解除 TTL，可能会导致之前因
TTL 而不可见的数据重新出现。
-系统中仅能设置至多 1000 条 TTL 规则，达到该上限时，需要先删除部分 TTL 规则才能设置新的规则
+IoTDB 支持对设备（device）级别设置数据保留时间（TTL），允许系统自动定期删除旧数据，以有效控制磁盘空间并维护高性能查询和低内存占用。TTL
默认以毫秒为单位，数据过期后不可查询且禁止写入，但物理删除会延迟至压缩时。需注意，TTL 变更可能导致短暂数据可查询性变化，且若调小或解除 TTL，之前因
TTL 不可见的数据可能重新出现。
+
+注意事项：
+- TTL 设置为毫秒，不受配置文件时间精度影响。
+- TTL 变更可能影响数据的可查询性。
+- 系统最终会移除过期数据，但存在延迟。
+- TTL 判断数据是否过期依据的是数据点时间，非写入时间。
+- 系统最多支持设置 1000 条 TTL 规则，达到上限需先删除部分规则才能设置新规则。
#### TTL Path 规则
设置的路径 path 只支持前缀路径（即路径中间不能带 \* ， 且必须以 \*\* 结尾），该路径会匹配到设备，也允许用户指定不带星的 path 为具体的
database 或 device，当 path 不带 \* 时，会检查是否匹配到 database，若匹配到 database，则会同时设置 path 和
path.\*\*。
diff --git a/src/zh/UserGuide/latest/Basic-Concept/Operate-Metadata_timecho.md
b/src/zh/UserGuide/latest/Basic-Concept/Operate-Metadata_timecho.md
index 6c26fe73..776ace71 100644
--- a/src/zh/UserGuide/latest/Basic-Concept/Operate-Metadata_timecho.md
+++ b/src/zh/UserGuide/latest/Basic-Concept/Operate-Metadata_timecho.md
@@ -147,14 +147,14 @@ It costs 0.002s
### 1.5 数据保留时间（TTL）
-IoTDB 支持对 device 级别设置数据保留时间（TTL），这使得 IoTDB 可以定期、自动地删除一定时间之前的数据。合理使用 TTL可以帮助您控制
IoTDB
占用的总磁盘空间以避免出现磁盘写满等异常。并且，随着文件数量的增多，查询性能往往随之下降，内存占用也会有所提高。及时地删除一些较老的文件有助于使查询性能维持在一个较高的水平和减少内存资源的占用。
-
-TTL的默认单位为毫秒，如果配置文件中的时间精度修改为其他单位，设置ttl时仍然使用毫秒单位。
-
-当设置 TTL 时，系统会根据设置的路径寻找所包含的所有 device，并为这些 device 设置 TTL
时间，系统会按设备粒度对过期数据进行删除。请注意，此处是否过期判断依据的是数据点时间，不是写入时间。
-当设备数据过期后，将不能被查询到，但磁盘文件中的数据不能保证立即删除（会在一定时间内删除），但可以保证最终被删除。
-考虑到操作代价，系统不会立即物理删除超过 TTL 的数据，而是通过合并来延迟地物理删除。因此，在数据被物理删除前，如果调小或者解除 TTL，可能会导致之前因
TTL 而不可见的数据重新出现。
-系统中仅能设置至多 1000 条 TTL 规则，达到该上限时，需要先删除部分 TTL 规则才能设置新的规则
+IoTDB 支持对设备（device）级别设置数据保留时间（TTL），允许系统自动定期删除旧数据，以有效控制磁盘空间并维护高性能查询和低内存占用。TTL
默认以毫秒为单位，数据过期后不可查询且禁止写入，但物理删除会延迟至压缩时。需注意，TTL 变更可能导致短暂数据可查询性变化，且若调小或解除 TTL，之前因
TTL 不可见的数据可能重新出现。
+
+注意事项：
+- TTL 设置为毫秒，不受配置文件时间精度影响。
+- TTL 变更可能影响数据的可查询性。
+- 系统最终会移除过期数据，但存在延迟。
+- TTL 判断数据是否过期依据的是数据点时间，非写入时间。
+- 系统最多支持设置 1000 条 TTL 规则，达到上限需先删除部分规则才能设置新规则。
#### TTL Path 规则
设置的路径 path 只支持前缀路径（即路径中间不能带 \* ， 且必须以 \*\* 结尾），该路径会匹配到设备，也允许用户指定不带星的 path 为具体的
database 或 device，当 path 不带 \* 时，会检查是否匹配到 database，若匹配到 database，则会同时设置 path 和
path.\*\*。
