mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-09-20 16:50:48 +00:00
82 lines
5.1 KiB
Markdown
82 lines
5.1 KiB
Markdown
---
|
|
slug: /en/operations/system-tables/part_log
|
|
---
|
|
# part_log
|
|
|
|
The `system.part_log` table is created only if the [part_log](../../operations/server-configuration-parameters/settings.md#server_configuration_parameters-part-log) server setting is specified.
|
|
|
|
This table contains information about events that occurred with [data parts](../../engines/table-engines/mergetree-family/custom-partitioning-key.md) in the [MergeTree](../../engines/table-engines/mergetree-family/mergetree.md) family tables, such as adding or merging data.
|
|
|
|
The `system.part_log` table contains the following columns:
|
|
|
|
- `query_id` ([String](../../sql-reference/data-types/string.md)) — Identifier of the `INSERT` query that created this data part.
|
|
- `event_type` ([Enum8](../../sql-reference/data-types/enum.md)) — Type of the event that occurred with the data part. Can have one of the following values:
|
|
- `NewPart` — Inserting of a new data part.
|
|
- `MergeParts` — Merging of data parts.
|
|
- `DownloadParts` — Downloading a data part.
|
|
- `RemovePart` — Removing or detaching a data part using [DETACH PARTITION](../../sql-reference/statements/alter/partition.md#alter_detach-partition).
|
|
- `MutatePart` — Mutating of a data part.
|
|
- `MovePart` — Moving the data part from the one disk to another one.
|
|
- `merge_reason` ([Enum8](../../sql-reference/data-types/enum.md)) — The reason for the event with type `MERGE_PARTS`. Can have one of the following values:
|
|
- `NotAMerge` — The current event has the type other than `MERGE_PARTS`.
|
|
- `RegularMerge` — Some regular merge.
|
|
- `TTLDeleteMerge` — Cleaning up expired data.
|
|
- `TTLRecompressMerge` — Recompressing data part with the.
|
|
- `merge_algorithm` ([Enum8](../../sql-reference/data-types/enum.md)) — Merge algorithm for the event with type `MERGE_PARTS`. Can have one of the following values:
|
|
- `Undecided`
|
|
- `Horizontal`
|
|
- `Vertical`
|
|
- `event_date` ([Date](../../sql-reference/data-types/date.md)) — Event date.
|
|
- `event_time` ([DateTime](../../sql-reference/data-types/datetime.md)) — Event time.
|
|
- `event_time_microseconds` ([DateTime64](../../sql-reference/data-types/datetime64.md)) — Event time with microseconds precision.
|
|
- `duration_ms` ([UInt64](../../sql-reference/data-types/int-uint.md)) — Duration.
|
|
- `database` ([String](../../sql-reference/data-types/string.md)) — Name of the database the data part is in.
|
|
- `table` ([String](../../sql-reference/data-types/string.md)) — Name of the table the data part is in.
|
|
- `part_name` ([String](../../sql-reference/data-types/string.md)) — Name of the data part.
|
|
- `partition_id` ([String](../../sql-reference/data-types/string.md)) — ID of the partition that the data part was inserted to. The column takes the `all` value if the partitioning is by `tuple()`.
|
|
- `path_on_disk` ([String](../../sql-reference/data-types/string.md)) — Absolute path to the folder with data part files.
|
|
- `rows` ([UInt64](../../sql-reference/data-types/int-uint.md)) — The number of rows in the data part.
|
|
- `size_in_bytes` ([UInt64](../../sql-reference/data-types/int-uint.md)) — Size of the data part in bytes.
|
|
- `merged_from` ([Array(String)](../../sql-reference/data-types/array.md)) — An array of names of the parts which the current part was made up from (after the merge).
|
|
- `bytes_uncompressed` ([UInt64](../../sql-reference/data-types/int-uint.md)) — Size of uncompressed bytes.
|
|
- `read_rows` ([UInt64](../../sql-reference/data-types/int-uint.md)) — The number of rows was read during the merge.
|
|
- `read_bytes` ([UInt64](../../sql-reference/data-types/int-uint.md)) — The number of bytes was read during the merge.
|
|
- `peak_memory_usage` ([Int64](../../sql-reference/data-types/int-uint.md)) — The maximum difference between the amount of allocated and freed memory in context of this thread.
|
|
- `error` ([UInt16](../../sql-reference/data-types/int-uint.md)) — The code number of the occurred error.
|
|
- `exception` ([String](../../sql-reference/data-types/string.md)) — Text message of the occurred error.
|
|
|
|
The `system.part_log` table is created after the first inserting data to the `MergeTree` table.
|
|
|
|
**Example**
|
|
|
|
``` sql
|
|
SELECT * FROM system.part_log LIMIT 1 FORMAT Vertical;
|
|
```
|
|
|
|
``` text
|
|
Row 1:
|
|
──────
|
|
query_id: 983ad9c7-28d5-4ae1-844e-603116b7de31
|
|
event_type: NewPart
|
|
merge_reason: NotAMerge
|
|
merge_algorithm: Undecided
|
|
event_date: 2021-02-02
|
|
event_time: 2021-02-02 11:14:28
|
|
event_time_microseconds: 2021-02-02 11:14:28.861919
|
|
duration_ms: 35
|
|
database: default
|
|
table: log_mt_2
|
|
part_name: all_1_1_0
|
|
partition_id: all
|
|
path_on_disk: db/data/default/log_mt_2/all_1_1_0/
|
|
rows: 115418
|
|
size_in_bytes: 1074311
|
|
merged_from: []
|
|
bytes_uncompressed: 0
|
|
read_rows: 0
|
|
read_bytes: 0
|
|
peak_memory_usage: 0
|
|
error: 0
|
|
exception:
|
|
```
|