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sql-statement-drop-stats: fix STATS_META output after DROP STATS #21887

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sql-statement-drop-stats: fix STATS_META output after DROP STATS #21887

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11 changes: 10 additions & 1 deletion sql-statements/sql-statement-drop-stats.md
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Original file line number Diff line number Diff line change
Expand Up @@ -81,12 +81,21 @@ DROP STATS t;
Query OK, 0 rows affected (0.00 sec)
```

执行 `DROP STATS` 后，`SHOW STATS_META` 仍会返回该表的行数和修改计数。
`DROP STATS` 会清除 TopN、bucket 等直方图相关统计信息，但不会删除
`STATS_META` 中对应的记录。
Comment on lines +85 to +86

@coderabbitai coderabbitai Bot Aug 18, 2026

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🎯 Functional Correctness | 🟡 Minor | ⚡ Quick win

不要把 TopN 归入直方图。

TopN 与直方图是两类独立的统计信息。bucket 属于直方图。当前措辞会错误地将 TopN 归类为直方图。官方统计信息文档也将两者分开说明。(docs.pingcap.com)

As per path instructions: 对可以安全替换的连续 Markdown 行提供 committable suggestion。

Suggested change
`DROP STATS` 会清除 TopN、bucket 等直方图相关统计信息，但不会删除
`STATS_META` 中对应的记录。
`DROP STATS` 会清除 TopN、直方图 bucket 等统计信息，但不会删除
`STATS_META` 中对应的记录。

Source: Path instructions


```sql
SHOW STATS_META WHERE db_name='test' and table_name='t';
```

```
Empty set (0.00 sec)
+---------+------------+----------------+---------------------+--------------+-----------+
| Db_name | Table_name | Partition_name | Update_time | Modify_count | Row_count |
+---------+------------+----------------+---------------------+--------------+-----------+
| test | t | | 2020-05-25 20:34:33 | 0 | 0 |
+---------+------------+----------------+---------------------+--------------+-----------+
1 row in set (0.00 sec)
Comment on lines +93 to +98

@coderabbitai coderabbitai Bot Aug 18, 2026

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🎯 Functional Correctness | 🟡 Minor | ⚡ Quick win

🧩 Analysis chain

🏁 Script executed:

#!/bin/bash
set -e
printf '%s\n' '--- changed file context ---'
sed -n '70,110p' sql-statements/sql-statement-drop-stats.md
printf '%s\n' '--- SHOW STATS_META documentation references ---'
rg -n -C 4 'Last_analyze_time|SHOW STATS_META|Update_time|Modify_count|Row_count' sql-statements/sql-statement-show-stats-meta.md sql-statements
printf '%s\n' '--- repository version metadata ---'
rg -n 'TiDB v?[0-9]+\.[0-9]+|version|版本' README.md docs sql-statements 2>/dev/null | head -80 || true

Repository: pingcap/docs-cn

Length of output: 45540

🏁 Script executed:

#!/bin/bash
set -e
printf '%s\n' '--- branch and diff metadata ---'
git branch --show-current
git diff --stat
git diff -- sql-statements/sql-statement-drop-stats.md
printf '%s\n' '--- current branch version table ---'
sed -n '1,35p' README.md
printf '%s\n' '--- DROP STATS implementation references in tracked files ---'
rg -n -C 5 'LastAnalyzeTime|last_analyze_time|DropStats|DROP STATS|drop stats' --glob '*.{go,sql,md}' . | head -240

Repository: pingcap/docs-cn

Length of output: 12274

🌐 Web query:

site:github.com/pingcap/tidb "LastAnalyzeTime" "DROP STATS"

💡 Result:

The terms "LastAnalyzeTime" and "DROP STATS" are primarily associated with the TiDB distributed database system [1][2][3]. In TiDB: 1. DROP STATS: This is a SQL command used to remove collected table statistics from the system [4][5]. It is primarily used to clean up metadata when statistics become outdated, invalid, or are no longer needed [1][6]. The syntax typically takes the form DROP STATS <table_name> [5]. 2. LastAnalyzeTime: This is a field found in the mysql.stats_meta system table that records the timestamp of the last successful ANALYZE operation performed on a table [2][3][7]. It allows administrators to track when statistics were last refreshed [7]. Technical context regarding their interaction: - When DROP STATS is executed, the associated statistics are removed [6]. - Issues have historically been reported where a table's LastAnalyzeTime might persist or appear non-null even after stats have been dropped or if the table has never actually been analyzed [8]. - Developers often manage these behaviors to ensure that metadata consistency is maintained (e.g., ensuring LastAnalyzeTime reflects the actual state of statistical collection) [1][9][3]. For managing extended statistics specifically, newer versions of TiDB have shifted toward using ALTER TABLE... DROP TIDB_STATS to replace older, deprecated syntax, ensuring better consistency across the system [10].

Citations:

🌐 Web query:

site:docs.pingcap.com/tidb/stable "DROP STATS" "Last_analyze_time"

💡 Result:

There is no SQL command "DROP STATS Last_analyze_time". Based on standard database documentation (specifically TiDB, which utilizes both "DROP STATS" and "Last_analyze_time" terminology), these are two distinct concepts [1][2]. 1. DROP STATS: This is a valid SQL command used to delete the statistics of a specified table or its partitions [1]. The correct syntax for this command is: DROP STATS TableName; [1] 2. Last_analyze_time: This is not a command but a column name returned by the "SHOW STATS_META" statement [2]. It displays the timestamp of the last time a table was analyzed [2]. It appears you may have conflated a command with a metadata field. To manage table statistics, you can either drop them using DROP STATS [1] or view their current metadata, including the last analyze time, using: SHOW STATS_META; [2]

Citations:

🏁 Script executed:

#!/bin/bash
set -e
tmpdir="$(mktemp -d)"
trap 'rm -rf "$tmpdir"' EXIT
curl -fsSL 'https://api.github.com/repos/pingcap/tidb/git/trees/master?recursive=1' \
  | jq -r '.tree[] | select(.type=="blob" and (.path|test("\\.(go|sql)$"))) | .path' \
  | rg 'statistics|executor|infoschema|parser' > "$tmpdir/paths"
printf '%s\n' '--- candidate source paths ---'
cat "$tmpdir/paths" | rg 'stats|statistics|infoschema' | head -120
printf '%s\n' '--- relevant current source lines ---'
while IFS= read -r path; do
  body="$(curl -fsSL "https://raw.githubusercontent.com/pingcap/tidb/master/$path" || true)"
  if printf '%s' "$body" | rg -q 'LastAnalyzeTime|last_analyze_time|DropStats'; then
    printf '%s\n' "### $path"
    printf '%s' "$body" | rg -n -C 5 'LastAnalyzeTime|last_analyze_time|DropStats' | head -160
  fi
done < <(rg 'stats|statistics' "$tmpdir/paths" | head -80)

Repository: pingcap/docs-cn

Length of output: 5471

🏁 Script executed:

#!/bin/bash
set -e
for path in \
  pkg/executor/show_stats.go \
  pkg/executor/infoschema_reader.go \
  pkg/parser/ast/stats.go \
  pkg/statistics/handle/handle.go \
  pkg/statistics/handle/storage.go
do
  body="$(curl -fsSL "https://raw.githubusercontent.com/pingcap/tidb/master/$path" || true)"
  if printf '%s' "$body" | rg -q 'LastAnalyzeTime|last_analyze_time|DropStats|DROP STATS'; then
    printf '%s\n' "### $path"
    printf '%s' "$body" | rg -n -C 8 'LastAnalyzeTime|last_analyze_time|DropStats|DROP STATS' | head -240
  fi
done

Repository: pingcap/docs-cn

Length of output: 2140

🏁 Script executed:

#!/bin/bash
set -e
curl -fsSL 'https://api.github.com/repos/pingcap/tidb/git/trees/master?recursive=1' |
  jq -r '.tree[] | select(.type=="blob") | .path' |
  rg '(^|/)(stats|statistics|analyze|infoschema|executor)([^/]*)(\.go|\.sql)$|stats_meta|statsmeta' |
  head -240

Repository: pingcap/docs-cn

Length of output: 4444

🏁 Script executed:

#!/bin/bash
set -e
for path in \
  pkg/ddl/executor.go \
  pkg/statistics/handle/storage/stats_read_writer.go \
  pkg/statistics/analyze.go \
  pkg/executor/analyze.go \
  pkg/infoschema/infoschema.go
do
  body="$(curl -fsSL "https://raw.githubusercontent.com/pingcap/tidb/master/$path")"
  printf '%s\n' "### $path"
  printf '%s' "$body" |
    rg -n -i -C 8 'drop stats|last[_a-z]*analy|stats_meta|statsmeta|analyze_time' |
    head -260 || true
done

Repository: pingcap/docs-cn

Length of output: 13338

🏁 Script executed:

#!/bin/bash
set -e
printf '%s\n' '--- DDL and SHOW-related source paths ---'
curl -fsSL 'https://api.github.com/repos/pingcap/tidb/git/trees/master?recursive=1' |
  jq -r '.tree[] | select(.type=="blob") | .path' |
  rg '(^|/)(ddl|executor|statistics|infoschema)/.*(stats|ddl|show|meta).*\.go$|(^|/)ddl/.*\.go$' |
  head -320

Repository: pingcap/docs-cn

Length of output: 10672

🏁 Script executed:

#!/bin/bash
set -e
for path in \
  pkg/executor/show_stats.go \
  pkg/executor/ddl.go \
  pkg/statistics/handle/ddl/ddl.go \
  pkg/ddl/stat.go
do
  body="$(curl -fsSL "https://raw.githubusercontent.com/pingcap/tidb/master/$path")"
  printf '%s\n' "### $path"
  printf '%s' "$body" |
    rg -n -i -C 12 'last[_a-z]*analy|stats_meta|statsmeta|dropstats|drop stats|delete.*stats|truncate.*stats' |
    head -360 || true
done

Repository: pingcap/docs-cn

Length of output: 5981

🏁 Script executed:

#!/bin/bash
set -e
for path in \
  pkg/statistics/handle/ddl/ddl.go \
  pkg/statistics/handle/storage/stats_read_writer.go \
  pkg/executor/ddl.go \
  pkg/ddl/stat.go
do
  body="$(curl -fsSL "https://raw.githubusercontent.com/pingcap/tidb/master/$path")"
  printf '%s\n' "### $path"
  printf '%s' "$body" |
    rg -n -i -C 10 'delete|remove|clear|reset|pseudo|analy[sz]|lastanaly|stats.*storage|storage.*stats' |
    head -420 || true
done

Repository: pingcap/docs-cn

Length of output: 16785

🏁 Script executed:

#!/bin/bash
set -e
curl -sS -D /tmp/tidb-search-headers \
  'https://api.github.com/search/code?q=DropStatsStmt+repo%3Apingcap%2Ftidb' \
  -o /tmp/tidb-search-body
printf '%s\n' '--- response status ---'
head -1 /tmp/tidb-search-headers
printf '%s\n' '--- response body ---'
cat /tmp/tidb-search-body
rm -f /tmp/tidb-search-headers /tmp/tidb-search-body

Repository: pingcap/docs-cn

Length of output: 336

🌐 Web query:

site:github.com/pingcap/tidb/issues "DROP STATS" "Last_analyze_time"

💡 Result:

There is no standard SQL command known as DROP STATS. Based on the provided search results, the term Last_analyze_time is a column found in database statistics metadata tables (such as mysql.stats_meta in TiDB), which tracks when a table's statistics were last updated via an ANALYZE operation [1][2]. The search results discuss the behavior, maintenance, and potential bugs regarding statistics collection and metadata, but do not contain any evidence of a command to drop statistics or interact with the Last_analyze_time column using a DROP STATS syntax [3][1][2]. If you are attempting to remove statistics, you should check your specific database management system's documentation for commands like ANALYZE (to update/refresh) or specific administrative procedures for managing or deleting statistics metadata.

Citations:

🌐 Web query:

site:github.com/pingcap/docs-cn "DROP STATS" "Last_analyze_time"

💡 Result:

The command DROP STATS is a specific SQL statement used in TiDB to delete table statistics [1][2]. There is no standard command or system variable named Last_analyze_time that is used with DROP STATS. It appears the user may be confusing the DROP STATS command with metadata or status monitoring commands [3]. In TiDB, you can view information about statistics and analyze jobs using: 1. SHOW ANALYZE STATUS: To see the status of statistics collection tasks, including start and end times [3]. 2. Information Schema tables: Such as the ANALYZE_STATUS table, which contains metadata about analyze jobs [3]. If the intention is to delete statistics for a table, the correct syntax is: DROP STATS TableName; [2] To delete statistics for specific partitions or global statistics in a partitioned table, you can use: DROP STATS TableName PARTITION PartitionNameList; [2] DROP STATS TableName GLOBAL; [2][4] If you are looking for the last time a table was analyzed, this information is typically found in the system tables (like mysql.stats_meta) or viewed via statistics-related inspection tools provided by the database, rather than through a DROP command.

Citations:

🌐 Web query:

site:docs.pingcap.com "DROP STATS" "Last_analyze_time" "NULL"

💡 Result:

There is no standard SQL command DROP STATS Last_analyze_time NULL. The DROP STATS statement in TiDB is used to delete all statistics for a specified table, not to reset individual metadata fields like Last_analyze_time [1][2][3]. If you are using TiDB and want to remove statistics for a table, the correct syntax is: DROP STATS TableName; [1][3] Regarding the Last_analyze_time field seen in SHOW STATS_META: - This field is system-generated and reflects the last time an ANALYZE operation was performed on the table [4][5][6]. - When no ANALYZE has been performed, or if statistics have been cleared, this value may appear as NULL [7]. - There is no direct command to manually set or "drop" this specific metadata field to NULL while retaining other statistics [1][8]. If your goal is to have Last_analyze_time appear as NULL, executing DROP STATS on the table will typically remove its statistics record entirely [1][3], which effectively removes the Last_analyze_time value along with all other stats data [7].

Citations:

🏁 Script executed:

#!/bin/bash
set -e
tmpdir="$(mktemp -d)"
trap 'rm -rf "$tmpdir"' EXIT
curl -fsSL 'https://codeload.github.com/pingcap/tidb/tar.gz/refs/heads/master' |
  tar -xz -C "$tmpdir"
root="$(find "$tmpdir" -mindepth 1 -maxdepth 1 -type d | head -1)"
printf '%s\n' '--- DropStatsStmt references ---'
rg -n -C 10 'DropStatsStmt|dropStats|DROP STATS|DropStats' "$root/pkg" | head -400
printf '%s\n' '--- stats metadata deletion/reset references ---'
rg -n -i -C 10 'last_analyze_time|lastanaly|delete from mysql\.stats_meta|stats_meta.*delete|delete.*stats_meta|truncate.*stats' "$root/pkg" | head -400

Repository: pingcap/docs-cn

Length of output: 50371

🏁 Script executed:

#!/bin/bash
set -e
tmpdir="$(mktemp -d)"
trap 'rm -rf "$tmpdir"' EXIT
curl -fsSL 'https://codeload.github.com/pingcap/tidb/tar.gz/refs/heads/master' |
  tar -xz -C "$tmpdir"
root="$(find "$tmpdir" -mindepth 1 -maxdepth 1 -type d | head -1)"
printf '%s\n' '--- executeDropStats ---'
sed -n '3530,3605p' "$root/pkg/executor/simple.go"
printf '%s\n' '--- soft-delete storage logic ---'
sed -n '125,180p' "$root/pkg/statistics/handle/storage/gc.go"
printf '%s\n' '--- stats load reset logic ---'
sed -n '500,550p' "$root/pkg/statistics/handle/storage/read.go"

Repository: pingcap/docs-cn

Length of output: 7250

补充 Last_analyze_time 列。

DROP STATS 后，SHOW STATS_META 仍返回七列；未分析统计信息时，Last_analyze_time 为 NULL。

Suggested change
+---------+------------+----------------+---------------------+--------------+-----------+
| Db_name | Table_name | Partition_name | Update_time | Modify_count | Row_count |
+---------+------------+----------------+---------------------+--------------+-----------+
| test | t | | 2020-05-25 20:34:33 | 0 | 0 |
+---------+------------+----------------+---------------------+--------------+-----------+
1 row in set (0.00 sec)
+---------+------------+----------------+---------------------+--------------+-----------+---------------------+
| Db_name | Table_name | Partition_name | Update_time | Modify_count | Row_count | Last_analyze_time |
+---------+------------+----------------+---------------------+--------------+-----------+---------------------+
| test | t | | 2020-05-25 20:34:33 | 0 | 0 | NULL |
+---------+------------+----------------+---------------------+--------------+-----------+---------------------+
1 row in set (0.00 sec)

Source: Path instructions

```

## MySQL 兼容性
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