data parts in the MergeTree family tables, such as adding or merging data.
system.part_log table contains the following columns:
query_id(String) — Identifier of the
INSERTquery that created this data part.
event_type(Enum8) — Type of the event that occurred with the data part. Can have one of the following values:
NEW_PART— Inserting of a new data part.
MERGE_PARTS— Merging of data parts.
DOWNLOAD_PART— Downloading a data part.
REMOVE_PART— Removing or detaching a data part using DETACH PARTITION.
MUTATE_PART— Mutating of a data part.
MOVE_PART— Moving the data part from the one disk to another one.
event_date(Date) — Event date.
event_time(DateTime) — Event time.
event_time_microseconds(DateTime64) — Event time with microseconds precision.
duration_ms(UInt64) — Duration.
database(String) — Name of the database the data part is in.
table(String) — Name of the table the data part is in.
part_name(String) — Name of the data part.
partition_id(String) — ID of the partition that the data part was inserted to. The column takes the
allvalue if the partitioning is by
path_on_disk(String) — Absolute path to the folder with data part files.
rows(UInt64) — The number of rows in the data part.
size_in_bytes(UInt64) — Size of the data part in bytes.
merged_from(Array(String)) — An array of names of the parts which the current part was made up from (after the merge).
bytes_uncompressed(UInt64) — Size of uncompressed bytes.
read_rows(UInt64) — The number of rows was read during the merge.
read_bytes(UInt64) — The number of bytes was read during the merge.
peak_memory_usage(Int64) — The maximum difference between the amount of allocated and freed memory in context of this thread.
error(UInt16) — The code number of the occurred error.
exception(String) — Text message of the occurred error.
system.part_log table is created after the first inserting data to the
SELECT * FROM system.part_log LIMIT 1 FORMAT Vertical;
Row 1: ────── query_id: 983ad9c7-28d5-4ae1-844e-603116b7de31 event_type: NewPart 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:
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