#### a).启动服务
sudo service clickhouse-server start
#### b).停止服务
sudo service clickhouse-server stop
Ⅳ).客户端访问
clickhouse-client
二.常用命令
Ⅰ).创建表
CREATE TABLE IF NOT EXISTS database.table_name ON cluster cluster_shardNum_replicasNum(
'id' UInt64,
'name' String,
'time' UInt64,
'age' UInt8,
'flag' UInt8
)
ENGINE = MergeTree
PARTITION BY toDate(time/1000)
ORDER BY (id,name)
SETTINGS index_granularity = 8192
Ⅱ).创建物化视图
CREATE MATERIALIZED VIEW database.view_name ON cluster cluster_shardNum_replicasNum
ENGINE = AggregatingMergeTree
PARTITION BY toYYYYMMDD(time)
ORDER BY (id,name)
AS SELECT
toStartOfHour(toDateTime(time/1000)) as time,
id,
name,
sumState( if (flag = 1, 1, 0)) AS successCount,
sumState( if (flag = 0, 1, 0)) AS faildCount,
sumState( if ((age < 10), 1, 0)) AS rang1Age,
sumState( if ((age > 10) AND (age < 20), 2, 0)) AS rang2Age,
sumState( if ((age > 20), 3, 0)) AS rang3Age,
maxState(age) AS maxAge,
minState(age) AS minAge
FROM datasource.table_name
GROUP BY time,id,name
Ⅲ).插入数据
a).普通数据插入
INSERT INTO database.table_name(id, name, age, flag) VALUES(1, 'test', 15, 0)
b).Json数据插入
INSERT INTO database.table_name FORMAT JSONEachRow{"id":"1", "name":"test", "age":"11", "flag":"1"}
Ⅳ).查询数据
a).表数据查询
SELECT * FROM database.table_name WHERE id=1
b).物化视图查询
SELECT id, name, sumMerge(successCount), sumMerge(faildCount), sumMerge(rang1Age), sumMerge(rang2Age), maxMerge(maxAge), minMerge(minAge)
FROM database.view_name
WHERE id=1
GROUP BY id, name
Ⅴ).创建NESTED表
CREATE TABLE IF NOT EXISTS database.table_name(
'id' UInt64,
'name' String,
'time' UInt64,
'age' UInt8,
'flag' UInt8
nested_table_name Nested (
sequence UInt32,
id UInt64,
name String,
time UInt64,
age UInt8,
flag UInt8
socketAddr String,
socketRemotePort UInt32,
socketLocalPort UInt32,
eventTime UInt64,
exceptionClassName String,
hashCode Int32,
nextSpanId UInt64
))
ENGINE = MergeTree
PARTITION BY toDate (time / 1000)
ORDER BY (id, name, time)
SETTINGS index_granularity = 8192
Ⅵ).NESTED表数据查询
SELECT table1.*,table1.id FROM nest.table_name AS table1 array JOIN nested_table_name AS table2
SELECT
id,
dictGet('name', 'name', toUInt64(name)) AS name,
dictGetString('url', 'url', tuple(url)) AS url
FROM table_name
Ⅸ).导入数据
clickhouse-client --query="INSERT INTO database.table_name FORMAT CSVWithNames" < /path/import_filename.csv
Ⅹ).导出数据
clickhouse-client --query="SELECT * FROM database.table_name FORMAT CSV" sed 's/"//g' > /path/export_filename.csv
Ⅺ).查看partition状态
SELECT table, name, partition，active FROM system.parts WHERE database='database_name'
Ⅻ).清理partition
ALTER TABLE database.table_name ON cluster cluster_shardNum_replicasNum detach partition 'partition_id'
XIII).查看列的压缩率
SELECT
database,
table,
name,
formatReadableSize(sum(data_compressed_bytes) AS c) AS comp,
formatReadableSize(sum(data_uncompressed_bytes) AS r) AS raw,
c/r AS comp_ratio
FROM system.columns
WHERE database='database_name'
AND table='table_name'
GROUP BY name
XIV).查看物化视图的磁盘占用
clickhouse-client --query="SELECT partition,count(*) AS partition_num, formatReadableSize(sum(bytes)) AS disk_size FROM system.columns WHERE database='database_name' " --external --?le=***.sql --name=parts --structure='table String, name String, partition UInt64, engine String' -h hostname
#!/bin/bash
#
# Script to start LVS DR real server.
# description: LVS DR real server
#
#. /etc/rc.d/init.d/functions
VIP=10.10.6.252
host='/bin/hostname'
case "$1" in
sta
大多数java开发者使用的都是eclipse，今天感兴趣去eclipse官网搜了一下eclipse.ini的配置，供大家参考，我会把关键的部分给大家用中文解释一下。还是推荐有问题不会直接搜谷歌，看官方文档，这样我们会知道问题的真面目是什么，对问题也有一个全面清晰的认识。
Overview
1、Eclipse.ini的作用
Eclipse startup is controlled by th
import java.util.Arrays;
/**
* 最早是在陈利人老师的微博看到这道题：
* #面试题#An array with n elements which is K most sorted，就是每个element的初始位置和它最终的排序后的位置的距离不超过常数K
* 设计一个排序算法。It should be faster than O(n*lgn)。
原网页被墙，放这里备用。 MySQLdb User's Guide
Contents
Introduction
Installation
_mysql
MySQL C API translation
MySQL C API function mapping
Some _mysql examples
MySQLdb
