Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

op-guide: fix variable description #670

Merged
merged 1 commit into from
Oct 16, 2018
Merged

op-guide: fix variable description #670

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
7 changes: 4 additions & 3 deletions op-guide/history-read.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -10,7 +10,8 @@ This document describes how TiDB reads data from the history versions, how TiDB

## Feature description

TiDB implements a feature to read history data using the standard SQL interface directly without special clients or drivers. By using this feature,
TiDB implements a feature to read history data using the standard SQL interface directly without special clients or drivers. By using this feature:

- Even when data is updated or removed, its history versions can be read using the SQL interface.
- Even if the table structure changes after the data is updated, TiDB can use the old structure to read the history data.

Expand Down Expand Up @@ -107,7 +108,7 @@ Pay special attention to the following two variables:
Query OK, 0 rows affected (0.00 sec)
```

> **Note:** You should use `@@` instead of `@` before `tidb_snapshot` because `@@` is used to denote the global variable while `@` is used to denote the session variable.
> **Note:** You should use `@@` instead of `@` before `tidb_snapshot` because `@@` is used to denote the system variable while `@` is used to denote the user variable.

**Result:** The read from the following statement is the data before the update operation, which is the history data.

Expand Down Expand Up @@ -142,4 +143,4 @@ Pay special attention to the following two variables:
3 rows in set (0.00 sec)
```

> **Note:** You should use `@@` instead of `@` before `tidb_snapshot` because `@@` is used to denote the global variable while `@` is used to denote the session variable.
> **Note:** You should use `@@` instead of `@` before `tidb_snapshot` because `@@` is used to denote the system variable while `@` is used to denote the user variable.