github ssh 失败 ssh 失败 github 可能会屏蔽 22 的 ssh 端口，导致使用 ssh 协议拉取推送代码失败 解决方法为使用 443 端口，同时将 hostname 改为 ssh.github.com​ host github.com Hostname ssh.github.com...

0x01-8级锁的不对称性 2024-08-17 00:14:26 +0800 用于创建索引的 SHARE LOCK，虽然和修改时需要的 ROW EXCL 锁冲突，却不和自己冲突。虽然创建索引时不能插入数据，但是可以创建其他索引。 SHARE 这个名字非常贴切。 注意：create index 可以事务块中执行 test=# begin transaction; BEGIN test=*# insert into test values (1); INSERT 0 1 test=*# create index on test (a); CREATE INDEX test=*# commit; COMMIT 而为了不阻塞读写，持有 SHARE UPDATE EXCL 锁的行为， 例如 vacuum , create index concurrent ，大都不能在事务块中进行。原因可能是这些操作需要感知其他正在执行的事务的状态(status of running processes)，其行为超出了一般意义上 MVCC 的。

c - What does -fwrapv do? - Stack Overflow -fwrapv tells the compiler that overflow of signed integer arithmetic must be treated as well-defined behavior, even though it is undefined in the C standard. It has two meaning full results: INT_MAX + 1 is overflowed to INT_MIN correctly. This is almost the default behavior in gcc. Don’t let the compiler assume x + 1 > x. See the program below...

0x0 what is inode From https://en.wikipedia.org/wiki/Inode The inode (index node) is a data structure in a Unix-style file system that describes a file-system object such as a file or a directory. Each inode stores the attributes and disk block locations of the object’s data From https://www.redhat.com/sysadmin/inodes-linux-filesystem By definition, an inode is an index node. It serves as a unique identifier for a specific piece of metadata on a given filesystem. Each piece of metadata describes what we think of as a file....

Download through git See official docs for detail. Below is a simple example: export user=dev export src_dir=postgresql export build_dir=/home/${user}/build export data_dir=/home/${user}/data export superuser=postgres export defaultdb=test ${build_dir}/bin/pg_ctl -D ${data_dir} stop rm -rf ${build_dir} rm -rf ${data} cd ~ #start from home/${user} git clone https://git.postgresql.org/git/postgresql.git cd ${src_dir} git clean -xdf # may be too dangerous # delete for add some configures accordingly ./configure \ --prefix=${build_dir} \ --enable-cassert \ --with-tcl \ --with-perl \ --with-python \ --enable-debug \ --without-icu \ --with-openssl \ CC=/usr/bin/gcc \ CFLAGS='-O0 -pipe -Wall -g3' make -j8 && make install make -C contrib install ${build_dir}/bin/initdb --username=${superuser} --pgdata=${data_dir} ${build_dir}/bin/pg_ctl -D ${data_dir} -l ${data_dir}/logfile start ${build_dir}/bin/psql -U${superuser} postgres -c "create database ${defaultdb};" echo "----------------- all finished -----------------------" echo "use ************** " echo "[ ${build_dir}/bin/psql -U${superuser} ${defaultdb} ] " echo "to connect postgresql" cd ....