ClickHouse/docs/en/operations/system-tables/merges.md

slug
/en/operations/system-tables/merges

merges

Contains information about merges and part mutations currently in process for tables in the MergeTree family.

Columns:

• database (String) — The name of the database the table is in.
• table (String) — Table name.
• elapsed (Float64) — The time elapsed (in seconds) since the merge started.
• progress (Float64) — The percentage of completed work from 0 to 1.
• num_parts (UInt64) — The number of pieces to be merged.
• result_part_name (String) — The name of the part that will be formed as the result of merging.
• is_mutation (UInt8) — 1 if this process is a part mutation.
• total_size_bytes_compressed (UInt64) — The total size of the compressed data in the merged chunks.
• total_size_marks (UInt64) — The total number of marks in the merged parts.
• bytes_read_uncompressed (UInt64) — Number of bytes read, uncompressed.
• rows_read (UInt64) — Number of rows read.
• bytes_written_uncompressed (UInt64) — Number of bytes written, uncompressed.
• rows_written (UInt64) — Number of rows written.
• memory_usage (UInt64) — Memory consumption of the merge process.
• thread_id (UInt64) — Thread ID of the merge process.
• merge_type — The type of current merge. Empty if it's an mutation.
• merge_algorithm — The algorithm used in current merge. Empty if it's an mutation.