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Merged
merged 5 commits into from
Apr 16, 2019
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Sql/transaction: changes on variables #1036

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2855bbd
fix the format error
huangxiuyan Apr 11, 2019
42052c6
Revert "fix the format error"
huangxiuyan Apr 11, 2019
2d9016c
sysbench-v4: fix a format error
huangxiuyan Apr 11, 2019
c563602
sql: changes on varaibles
huangxiuyan Apr 11, 2019
aeae05b
one quick grammatical error
huangxiuyan Apr 16, 2019
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4 changes: 3 additions & 1 deletion benchmark/sysbench-v4.md
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Expand Up @@ -13,8 +13,10 @@ This test aims to test the performance of TiDB 3.0 Beta on NVMe SSD.

## Test version, time, and place

TiDB version: 3.0 Beta
TiDB version: 3.0 Beta

Time: February, 2019

Place: Beijing

## Test environment
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7 changes: 2 additions & 5 deletions sql/transaction-isolation.md
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Expand Up @@ -54,9 +54,7 @@ The MySQL Repeatable Read isolation level is not the snapshot isolation level. T

## Transaction retry

Transactions that fail may automatically be retried by TiDB, which may lead to lost updates. This feature can be disabled by setting both `tidb_disable_txn_auto_retry=TRUE` and `tidb_retry_limit = 0`.

In addition, you can control the number of retries by configuring the `retry-limit` parameter:
Transactions that fail may automatically be retried by TiDB, which may lead to lost updates. This feature can be disabled by setting `tidb_retry_limit = 0`.

```
[performance]
Expand Down Expand Up @@ -97,10 +95,9 @@ Example 2:

Under the automatic retry mechanism of TiDB, all the executed statements for the first time are re-executed again. Whether the subsequent statements are to be executed or not depends on the results of the previous statements, automatic retry can violate snapshot isolation, causing lost updates.

To disable the automatic retry of explicit transactions, configure the `tidb_disable_txn_auto_retry` and `tidb_retry_limit` variables:
To disable the automatic retry of explicit transactions, configure the `tidb_retry_limit` variable:

```sql
SET GLOBAL tidb_disable_txn_auto_retry = TRUE;
SET GLOBAL tidb_retry_limit = 0;
```

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2 changes: 1 addition & 1 deletion sql/transaction-model.md
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Expand Up @@ -16,7 +16,7 @@ Similarly, functions such as `GET_LOCK()` and `RELEASE_LOCK()` and statements su

### Transaction retry

By default, transactions that fail may automatically be retried by TiDB, which may lead to lost updates. This feature can be disabled by setting both `tidb_disable_txn_auto_retry = TRUE` and `tidb_retry_limit = 0`.
By default, transactions that fail may automatically be retried by TiDB, which may lead to lost updates. This feature can be disabled by setting `tidb_retry_limit = 0`.

### Large transactions

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