Engine void MaterializeMetadata::transaction(const MySQLReplication::Position & position, const std::function & fun) { String persistent_tmp_path = persistent_path + ".tmp"; { out); out.next(); out.sync(); out.close(); } commitMetadata(std::move(fun), persistent_tmp_path, persistent_path); } Select history data MaterializeMySQL Database iterator->second, query_context, database_name, comment); /// create table. auto out = std::make_shared(getTableOutput(database_name, table_name, query_context));

медленные за счет дополнительных фетчей из памяти Метод цепочек 13 13 Метод цепочек 14 14 Пример: std::unordered_map 1. Стабильность указателей на ключ, значение 2. Возможность хранить большие объекты Хеш-таблица Время ClickHouse HashMap 7.366 сек. Google DenseMap 10.089 сек. Abseil HashMap 9.011 сек. std::unordered_map 44.758 сек. Бенчмарки 28 28 perf stat -e cache-misses:u ./integer_hash_tables_and_hashes Cache misses ClickHouse HashMap 329,664,616 Google DenseMap 383,350,820 Abseil HashMap 415,869,669 std::unordered_map 1,939,811,017 Бенчмарки 29 29 http://norvig.com/21-days.html#answers Бенчмарки

26 Going Further Begin Content Area = 16,30 27 Inline C++ in SQL SELECT udsf(' std::string udsf(std::string s) { return "hello, " + s; } ', 'world') • Compiled and linked

例例⼦子 ● CREATE OR REPLACE FUNCTION r_norm(n integer, mean float8, std_dev float8) RETURNS float8[ ] AS $$ x<-rnorm(n,mean,std_dev) return(x) $$ LANGUAGE 'plr'; ● CREATE TABLE test_norm_var

record Student std = (Student) session.selectOne("Student.getById", 1); System.out.println("Details of the student after update operation" ); System.out.println(std.toString());

Missing aliases: INSTR() for positionCaseInsensitive(), STR_TO_DATE() for parseDateTimeOrNull(), STD() for stddevPop(), … Different convenience vs. type-safety philosophies in ClickHouse / MySQL. -

SACC2017 网络模块--Pink class MyPbConn : public pink::PbConn { Public: MyPbConn(int fd, std::string ip_port, pink::Thread* self_thread_ptr = NULL) : pink::PbConn(fd, ip_port) { res_ =

111111111111127,1.14814814814815,1.01851851851852} r2 | 0.968612680477111 std_err | {1.49587911309236,0.207043331249903,0.346449758034495} t_stats rnorm(). CREATE OR REPLACE FUNCTION r_norm(n integer, mean float8, std_dev float8) RETURNS float8[ ] AS $$ x<-rnorm(n,mean,std_dev) return(x) $$ LANGUAGE 'plr'; The following CREATE TABLE command Greenplum will accept POSIX-style time zone specifications of the form STDoffset or STDoffsetDST, where STD is a zone abbreviation, offset is a numeric offset in hours west from UTC, and DST is an optional

{0.111111111111127,1.14814814814815,1.01851851851852} r2 | 0.968612680477111 std_err | {1.49587911309236,0.207043331249903,0.346449758034495} t_stats rnorm(). CREATE OR REPLACE FUNCTION r_norm(n integer, mean float8, std_dev float8) RETURNS float8[ ] AS $$ x<-rnorm(n,mean,std_dev) return(x) $$ LANGUAGE 'plr'; The following CREATE TABLE command Greenplum will accept POSIX-style time zone specifications of the form STDoffset or STDoffsetDST, where STD is a zone abbreviation, offset is a numeric offset in hours west from UTC, and DST is an optional

111111111111127,1.14814814814815,1.01851851851852} r2 | 0.968612680477111 std_err | {1.49587911309236,0.207043331249903,0.346449758034495} t_stats rnorm(). CREATE OR REPLACE FUNCTION r_norm(n integer, mean float8, std_dev float8) RETURNS float8[ ] AS $$ x<-rnorm(n,mean,std_dev) return(x) $$ LANGUAGE 'plr'; The following CREATE TABLE command Greenplum will accept POSIX-style time zone specifications of the form STDoffset or STDoffsetDST, where STD is a zone abbreviation, offset is a numeric offset in hours west from UTC, and DST is an optional