zhjwpku

-- Set number of shard
ALTER DATABASE citus SET citus.shard_count = 64;

-- distribute the table
SELECT create_distributed_table('github_events', 'repo_id');

-- undo that and make it local again
SELECT undistribute_table('github_events');

-- change distribution column

zhjwpku

Electron apps

• Marp: Markdown presentation ecosystem.

• muryoimpl/slippr: markdown presentation app by Electron

• joe-re/cafe-pitch Markdown-driven presentation tool built on Electron.

Slide deck frameworks supporting Markdown source

zhjwpku

sudo apt update
sudo apt upgrade
sudo apt install -y zsh neovim

## set ecs-user / hellogpdb
sudo passwd ecs-user

## make ecs can access github
sudo bash -c bash
echo "140.82.114.4   github.com" >> /etc/hosts

zhjwpku

CREATE TABLE customer_zlib (
    c_custkey integer NOT NULL,
    c_name character varying(25) NOT NULL,
    c_address character varying(40) NOT NULL,
    c_nationkey integer NOT NULL,
    c_phone character(15) NOT NULL,
    c_acctbal numeric(15,2) NOT NULL,
    c_mktsegment character(10) NOT NULL,
    c_comment character varying(117) NOT NULL
) with (appendoptimized=true, compresstype=zlib, orientation=column) distributed by (c_custkey);

zhjwpku

CREATE TABLE customer_zstd (
    c_custkey integer NOT NULL,
    c_name character varying(25) NOT NULL,
    c_address character varying(40) NOT NULL,
    c_nationkey integer NOT NULL,
    c_phone character(15) NOT NULL,
    c_acctbal numeric(15,2) NOT NULL,
    c_mktsegment character(10) NOT NULL,
    c_comment character varying(117) NOT NULL
) with (appendoptimized=true, compresstype=zstd, orientation=column) distributed by (c_custkey);

zhjwpku

CREATE TABLE customer_lz4 (
    c_custkey integer NOT NULL,
    c_name character varying(25) NOT NULL,
    c_address character varying(40) NOT NULL,
    c_nationkey integer NOT NULL,
    c_phone character(15) NOT NULL,
    c_acctbal numeric(15,2) NOT NULL,
    c_mktsegment character(10) NOT NULL,
    c_comment character varying(117) NOT NULL
) with (appendoptimized=true, compresstype=lz4, compresslevel = 1, orientation=column) distributed by (c_custkey);

zhjwpku

create extension pg_buffercache;

-- 查看哪个数据库占用的缓存最多
select datname, count(*), count(*) filter (where isdirty = true) as dirty
  from pg_buffercache as b, pg_database as d
  where d.oid = b.reldatabase
  group by rollup (1);

-- 查看指定数据库中哪张表占用的缓存最多
select relname, relkind, count(*), count(*) filter (where isdirty = true) as dirty

zhjwpku

public class MaxNumString {
    public int Continumax(String intputStr,  StringBuffer outputStr){
        int maxlength=0;
        StringBuffer maxNumberStr = null;

        int nowlength=0;
        StringBuffer nowNumberStr = null;


        for(int i=0;i<intputStr.length();i++){

zhjwpku

import java.util.Scanner;

public class Jiepijiu {
    public static void main(String [] args) {
        int w[] = new int[10010];
        int lastw[] = new int[10010];
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int m = scanner.nextInt();
        int time = 0;

zhjwpku

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Josephus {
    public static List<Integer> getResult(int n, int m) {
        List<Integer> circle = new ArrayList<>();

        for (int i = 1; i <= n; i++) {
            circle.add(i);