# [Known Issues] 在某些版本中不带 time 字段查询 slow_query 表返回结果不正确 

## Key Words

information_schema.slow_query, time, 结果不一致

## Description

查看 tidb-slow.log 信息

```sql
# Time: 2022-04-21T14:44:54.103041447+08:00
# Txn_start_ts: 432674816242745346
# Query_time: 59.251052432
# Parse_time: 0
# Compile_time: 21.36997765
# Rewrite_time: 2.107040149
# Optimize_time: 12.866449698
# Wait_TS: 1.485568827
# Cop_time: 8.619838386 Request_count: 1 Total_keys: 1 Rocksdb_block_cache_hit_count: 3
# Index_names: [bind_info:time_index]
# Is_internal: true
# Digest: caf0da652413a857b1ded77811703043e52753ca8a466e20e89c6b74d9662783
# Stats: bind_info:pseudo
# Num_cop_tasks: 1
# Cop_proc_avg: 0 Cop_proc_addr: 172.16.6.173:40161
# Cop_wait_avg: 0 Cop_wait_addr: 172.16.6.173:40161
# Mem_max: 186
# Prepared: false
# Plan_from_cache: false
# Plan_from_binding: false
# Has_more_results: false
# KV_total: 4.032247202
# PD_total: 0.108570401
# Backoff_total: 0
# Write_sql_response_total: 0
# Result_rows: 0
# Succ: true
# IsExplicitTxn: false
# Plan: tidb_decode_plan('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')
# Plan_digest: c338c3017eb2e4980cb49c8f804fea1fb7c1104aede2385f12909cdd376799b3
SELECT original_sql, bind_sql, default_db, status, create_time, update_time, charset, collation, source  FROM mysql.bind_info WHERE update_time > '0000-00-00 00:00:00' ORDER BY update_time, create_time;
```

查询以下 SQL 结果为 1, 不符合预期, time 列为 2022-04-21T14:44:54 查询结果应该为 0

```sql
select count(digest) from information_schema.SLOW_QUERY where time>'2022-04-29 17:50:00';
```

查询以下 SQL 结果为 0, 符合预期

```sql
select time, digest from information_schema.SLOW_QUERY where time>'2022-04-29 17:50:00';
```

## Root Cause

当输出列包含 time 列时, 过滤条件中的 time>'2022-04-29 17:50:00' 才生效, 否则查询结果和全表扫描结果一致.

BUG 记录在 [Issue 34320](https://github.com/pingcap/tidb/issues/34320)

## Diagnostic Steps

查询 information_schema.slow_query 表两次, 验证包含 time 列是否输出一致, 类似如下查询

查询以下 SQL 结果为 1, 不符合预期, time 列为 2022-04-21T14:44:54 查询结果应该为 0

```sql
select count(digest) from information_schema.SLOW_QUERY where time>'2022-04-29 17:50:00';
```

查询以下 SQL 结果为 0, 符合预期

```sql
select time, digest from information_schema.SLOW_QUERY where time>'2022-04-29 17:50:00';
```

## Resolution

升级到 v5.3.2, v5.4.3 及之后版本修复

## Workaround

在查询条件中包含 time 列, 举例

```sql
select time, digest from information_schema.SLOW_QUERY where time>'2022-04-29 17:50:00';
```

## Affected Versions

v5.4.0 - v5.4.2

v5.3.0 - v5.3.1

v5.2.x