Clickhouse: Question: How to speed-up deletion of inactive parts ?

[healiseu]

Hi, in the system I build (associative-semiotic-hypergraph) performance is significantly better if I optimize my tables. But after optimization, the size of data is doubled.

I have read the relevant part of documentation where it says that:

"Inactive parts are, for example, source parts remaining after merging to a larger part – these parts are deleted approximately 10 minutes after merging."

How is it possible to speed-up deletion ?

Relevant Issues: #745
Relevant posts: If we drop and create the same partition, do we need to wait for the drop to succeed, before creating the same partition?

[alex-zaitsev]

It is controlled by merge tree setting old_parts_lifetime. Default is 480s, or 8 mins. You can change it at server level or per table.

[healiseu]

@alex-zaitsev I have used a SETTINGS directive in CREATE TABLE e.g.

CREATE TABLE Test (   
    dim3 UInt16,
    dim2 UInt16,
    dim1 UInt16,

    val  Float32,
    sel  UInt8)

 ENGINE = MergeTree()
 PARTITION BY (dim3, dim2)
 ORDER BY (dim3, dim2, dim1)
 SETTINGS old_parts_lifetime = 120
''');

It works. How can I view the settings of this table ;

[alex-zaitsev]

@healiseu

SHOW CREATE TABLE.

Only overrides are shown. Global settings can be viewed in system.merge_tree_settings table (as of 18.10.3 release and later)

[healiseu]

OK thanks Alex, issue is closed