Clickhouse：列INDEX的值为0 1

如何解决Clickhouse：列INDEX的值为0 1

我试图提高查询的性能，该查询在UInt8列上包含WHERE子句，该子句仅包含0或1作为可能的值。我试图分解该问题，以确保没有其他因素（分区，PK ..）引起该问题。我创建了一个简单的表 index_text ，其中只有1列，并且有一组像这样的indizes：

CREATE TABLE default.index_text (
  `columnX` UInt8,INDEX indexX1 columnX TYPE minmax GRANULARITY 1,INDEX indexX2 columnX TYPE
  set(0) GRANULARITY 1,INDEX indexX3 columnX TYPE
  set(1) GRANULARITY 1
) ENGINE = MergeTree()
ORDER BY
  tuple() SETTINGS index_granularity = 8192

在那之后，我用约25百万个随机值（0或1）填充了表格。我希望印度人会在此查询上放下颗粒，但事实并非如此：

SELECT COUNT(*) FROM index_text WHERE columnX = 0

SELECT COUNT(*)
FROM index_text
WHERE columnX = 0

[JWDebian] 2020.10.19 07:48:26.511085 [ 584 ] {af7615f0-f32b-47c5-87a2-e8acc8e27f5e} <Debug> executeQuery: (from [::1]:40088) SELECT COUNT(*) FROM index_text WHERE columnX = 0
[JWDebian] 2020.10.19 07:48:26.511384 [ 584 ] {af7615f0-f32b-47c5-87a2-e8acc8e27f5e} <Trace> ContextAccess (default): Access granted: SELECT(columnX) ON default.index_text
[JWDebian] 2020.10.19 07:48:26.511440 [ 584 ] {af7615f0-f32b-47c5-87a2-e8acc8e27f5e} <Debug> default.index_text (SelectExecutor): Key condition: unknown
[JWDebian] 2020.10.19 07:48:26.512611 [ 584 ] {af7615f0-f32b-47c5-87a2-e8acc8e27f5e} <Debug> default.index_text (SelectExecutor): Index `indexX1` has dropped 0 / 3050 granules.
[JWDebian] 2020.10.19 07:48:26.522601 [ 584 ] {af7615f0-f32b-47c5-87a2-e8acc8e27f5e} <Debug> default.index_text (SelectExecutor): Index `indexX2` has dropped 0 / 3050 granules.
[JWDebian] 2020.10.19 07:48:26.523699 [ 584 ] {af7615f0-f32b-47c5-87a2-e8acc8e27f5e} <Debug> default.index_text (SelectExecutor): Index `indexX3` has dropped 0 / 3050 granules.
[JWDebian] 2020.10.19 07:48:26.523722 [ 584 ] {af7615f0-f32b-47c5-87a2-e8acc8e27f5e} <Debug> default.index_text (SelectExecutor): Selected 1 parts by date,1 parts by key,3050 marks by primary key,3050 marks to read from 1 ranges
[JWDebian] 2020.10.19 07:48:26.523764 [ 584 ] {af7615f0-f32b-47c5-87a2-e8acc8e27f5e} <Trace> default.index_text (SelectExecutor): Reading approx. 24985600 rows with 2 streams
[JWDebian] 2020.10.19 07:48:26.523823 [ 584 ] {af7615f0-f32b-47c5-87a2-e8acc8e27f5e} <Trace> InterpreterSelectQuery: FetchColumns -> Complete
[JWDebian] 2020.10.19 07:48:26.525061 [ 620 ] {af7615f0-f32b-47c5-87a2-e8acc8e27f5e} <Trace> AggregatingTransform: Aggregating
[JWDebian] 2020.10.19 07:48:26.525087 [ 620 ] {af7615f0-f32b-47c5-87a2-e8acc8e27f5e} <Trace> Aggregator: Aggregation method: without_key
[JWDebian] 2020.10.19 07:48:26.530850 [ 621 ] {af7615f0-f32b-47c5-87a2-e8acc8e27f5e} <Trace> AggregatingTransform: Aggregating
[JWDebian] 2020.10.19 07:48:26.530893 [ 621 ] {af7615f0-f32b-47c5-87a2-e8acc8e27f5e} <Trace> Aggregator: Aggregation method: without_key
[JWDebian] 2020.10.19 07:48:26.598438 [ 620 ] {af7615f0-f32b-47c5-87a2-e8acc8e27f5e} <Trace> AggregatingTransform: Aggregated. 6509826 to 1 rows (from 6.21 MiB) in 0.074525217 sec. (87350648.03635526 rows/sec.,83.30 MiB/sec.)
[JWDebian] 2020.10.19 07:48:26.598976 [ 621 ] {af7615f0-f32b-47c5-87a2-e8acc8e27f5e} <Trace> AggregatingTransform: Aggregated. 6109074 to 1 rows (from 5.83 MiB) in 0.075064427 sec. (81384408.62274216 rows/sec.,77.61 MiB/sec.)
[JWDebian] 2020.10.19 07:48:26.598994 [ 621 ] {af7615f0-f32b-47c5-87a2-e8acc8e27f5e} <Trace> Aggregator: Merging aggregated data
┌──COUNT()─┐
│ 12618900 │
└──────────┘
[JWDebian] 2020.10.19 07:48:26.599322 [ 584 ] {af7615f0-f32b-47c5-87a2-e8acc8e27f5e} <Information> executeQuery: Read 24979658 rows,23.82 MiB in 0.088181578 sec.,283275243 rows/sec.,270.15 MiB/sec.
[JWDebian] 2020.10.19 07:48:26.599356 [ 584 ] {af7615f0-f32b-47c5-87a2-e8acc8e27f5e} <Debug> MemoryTracker: Peak memory usage (for query): 0.00 B.

我在这里做错了什么？对INDEX有概念上的误解？ INDEX的类型/参数错误？我正在使用ClickHouse服务器版本20.9.2修订版54439，因此我猜 allow_experimental_data_skipping_indices 设置不再重要。无奈之下，我将其设置为1，并在填充后查询了O PTIMIZE TABLE index_text FINAL ，但是结果是相同的。