Multiversion concurrency control (MVCC)

这里的版本号可以任何属性，只要当一次数据修改操作被执行后，这个属性一定会被改变即可，比如数据被修改的次数、版本号、时间戳（timestamp）。

Posted by Wei on 2023-07-18, Last Modified on 2025-08-11

【macOS】搜索不出来存在的文件

Posted by Wei on 2023-05-06, Last Modified on 2025-08-11

Context

$ pip3 install numpy
===>  _PYTHON_HOST_PLATFORM=x86_64-pc-linux-gnu /home/spksrc/py310.6/spksrc/spk/bazarr/work-x64-6.1/crossenv/cross/bin/pip wheel --disable-pip-version-check --no-binary :all: --cache-dir /home/spksrc/py310.6/spksrc/spk/bazarr/../../distrib/pip --no-deps --wheel-dir /home/spksrc/py310.6/spksrc/spk/bazarr/work-x64-6.1/wheelhouse --no-build-isolation greenlet==1.1.2
Collecting greenlet==1.1.2
  Using cached greenlet-1.1.2.tar.gz (91 kB)
  Preparing metadata (setup.py): started
  Preparing metadata (setup.py): finished with status 'done'
Building wheels for collected packages: greenlet
  Building wheel for greenlet (setup.py): started
  Building wheel for greenlet (setup.py): finished with status 'done'
  Created wheel for greenlet: filename=greenlet-1.1.2-cp310-cp310-linux_x86_64.whl size=142558 sha256=d3ac376cd9b322f76ee60208a103be9f52d989d3b3a8a1185fb9857c4a28de25
  Stored in directory: /home/spksrc/py310.6/spksrc/distrib/pip/wheels/51/01/b7/16995feb30f4eed2504aed2260a4058a1164472c9be5ab44b1
Successfully built greenlet
make[3]: Leaving directory '/home/spksrc/py310.6/spksrc/spk/bazarr'
===>  [numpy]           
make[3]: Entering directory '/home/spksrc/py310.6/spksrc/spk/bazarr'
===>  _PYTHON_HOST_PLATFORM=x86_64-pc-linux-gnu /home/spksrc/py310.6/spksrc/spk/bazarr/work-x64-6.1/crossenv/cross/bin/pip wheel --disable-pip-version-check --no-binary :all: --cache-dir /home/spksrc/py310.6/spksrc/spk/bazarr/../../distrib/pip --no-deps --wheel-dir /home/spksrc/py310.6/spksrc/spk/bazarr/work-x64-6.1/wheelhouse --no-build-isolation numpy==1.22.4
Collecting numpy==1.22.4
  Using cached numpy-1.22.4.zip (11.5 MB)
  Preparing metadata (pyproject.toml): started
  Preparing metadata (pyproject.toml): finished with status 'error'
  error: subprocess-exited-with-error
  
  × Preparing metadata (pyproject.toml) did not run successfully.
  │ exit code: 1
  ╰─> [75 lines of output]
      Running from numpy source directory.
      running dist_info
      running build_src
      INFO: build_src
      creating /tmp/pip-modern-metadata-8a5sb6si/numpy.egg-info
      writing /tmp/pip-modern-metadata-8a5sb6si/numpy.egg-info/PKG-INFO
      writing dependency_links to /tmp/pip-modern-metadata-8a5sb6si/numpy.egg-info/dependency_links.txt
      writing entry points to /tmp/pip-modern-metadata-8a5sb6si/numpy.egg-info/entry_points.txt
      writing top-level names to /tmp/pip-modern-metadata-8a5sb6si/numpy.egg-info/top_level.txt
      writing manifest file '/tmp/pip-modern-metadata-8a5sb6si/numpy.egg-info/SOURCES.txt'
      /home/spksrc/py310.6/spksrc/spk/bazarr/work-x64-6.1/crossenv/build/lib/python3.10/site-packages/setuptools/command/egg_info.py:643: SetuptoolsDeprecationWarning: Custom 'build_py' does not implement 'get_data_files_without_manifest'.
      Please extend command classes from setuptools instead of distutils.
        warnings.warn(
      INFO: unifing config_cc, config, build_clib, build_ext, build commands --compiler options
      INFO: unifing config_fc, config, build_clib, build_ext, build commands --fcompiler options
      Traceback (most recent call last):
        File "/home/spksrc/py310.6/spksrc/spk/bazarr/work-x64-6.1/crossenv/build/lib/python3.10/site-packages/pip/_vendor/pep517/in_process/_in_process.py", line 363, in <module>
          main()
        File "/home/spksrc/py310.6/spksrc/spk/bazarr/work-x64-6.1/crossenv/build/lib/python3.10/site-packages/pip/_vendor/pep517/in_process/_in_process.py", line 345, in main
          json_out['return_val'] = hook(**hook_input['kwargs'])
        File "/home/spksrc/py310.6/spksrc/spk/bazarr/work-x64-6.1/crossenv/build/lib/python3.10/site-packages/pip/_vendor/pep517/in_process/_in_process.py", line 164, in prepare_metadata_for_build_wheel
          return hook(metadata_directory, config_settings)
        File "/home/spksrc/py310.6/spksrc/spk/bazarr/work-x64-6.1/crossenv/build/lib/python3.10/site-packages/setuptools/build_meta.py", line 369, in prepare_metadata_for_build_wheel
          self.run_setup()
        File "/home/spksrc/py310.6/spksrc/spk/bazarr/work-x64-6.1/crossenv/build/lib/python3.10/site-packages/setuptools/build_meta.py", line 474, in run_setup
          super(_BuildMetaLegacyBackend,
        File "/home/spksrc/py310.6/spksrc/spk/bazarr/work-x64-6.1/crossenv/build/lib/python3.10/site-packages/setuptools/build_meta.py", line 334, in run_setup
          exec(code, locals())
        File "<string>", line 461, in <module>
        File "<string>", line 453, in setup_package
        File "/home/spksrc/py310.6/spksrc/spk/bazarr/work-x64-6.1/crossenv/build/lib/python3.10/site-packages/setuptools/__init__.py", line 87, in setup
          return distutils.core.setup(**attrs)
        File "/home/spksrc/py310.6/spksrc/spk/bazarr/work-x64-6.1/crossenv/build/lib/python3.10/site-packages/setuptools/_distutils/core.py", line 185, in setup
          return run_commands(dist)
        File "/home/spksrc/py310.6/spksrc/spk/bazarr/work-x64-6.1/crossenv/build/lib/python3.10/site-packages/setuptools/_distutils/core.py", line 201, in run_commands
          dist.run_commands()
        File "/home/spksrc/py310.6/spksrc/spk/bazarr/work-x64-6.1/crossenv/build/lib/python3.10/site-packages/setuptools/_distutils/dist.py", line 973, in run_commands
          self.run_command(cmd)
        File "/home/spksrc/py310.6/spksrc/spk/bazarr/work-x64-6.1/crossenv/build/lib/python3.10/site-packages/setuptools/dist.py", line 1217, in run_command
          super().run_command(command)
        File "/home/spksrc/py310.6/spksrc/spk/bazarr/work-x64-6.1/crossenv/build/lib/python3.10/site-packages/setuptools/_distutils/dist.py", line 992, in run_command
          cmd_obj.run()
        File "/home/spksrc/py310.6/spksrc/spk/bazarr/work-x64-6.1/crossenv/build/lib/python3.10/site-packages/setuptools/command/dist_info.py", line 96, in run
          self.egg_info.run()
        File "/tmp/pip-wheel-zx645048/numpy_62d5a1a8355144f781d4c843ede91f36/numpy/distutils/command/egg_info.py", line 25, in run
          _egg_info.run(self)
        File "/home/spksrc/py310.6/spksrc/spk/bazarr/work-x64-6.1/crossenv/build/lib/python3.10/site-packages/setuptools/command/egg_info.py", line 308, in run
          self.find_sources()
        File "/home/spksrc/py310.6/spksrc/spk/bazarr/work-x64-6.1/crossenv/build/lib/python3.10/site-packages/setuptools/command/egg_info.py", line 316, in find_sources
          mm.run()
        File "/home/spksrc/py310.6/spksrc/spk/bazarr/work-x64-6.1/crossenv/build/lib/python3.10/site-packages/setuptools/command/egg_info.py", line 560, in run
          self.add_defaults()
        File "/home/spksrc/py310.6/spksrc/spk/bazarr/work-x64-6.1/crossenv/build/lib/python3.10/site-packages/setuptools/command/egg_info.py", line 597, in add_defaults
          sdist.add_defaults(self)
        File "/home/spksrc/py310.6/spksrc/spk/bazarr/work-x64-6.1/crossenv/build/lib/python3.10/site-packages/setuptools/command/sdist.py", line 107, in add_defaults
          self._add_defaults_build_sub_commands()
        File "/home/spksrc/py310.6/spksrc/spk/bazarr/work-x64-6.1/crossenv/build/lib/python3.10/site-packages/setuptools/command/sdist.py", line 127, in _add_defaults_build_sub_commands
          self.filelist.extend(chain.from_iterable(files))
        File "/home/spksrc/py310.6/spksrc/spk/bazarr/work-x64-6.1/crossenv/build/lib/python3.10/site-packages/setuptools/command/egg_info.py", line 503, in extend
          self.files.extend(filter(self._safe_path, paths))
        File "/home/spksrc/py310.6/spksrc/spk/bazarr/work-x64-6.1/crossenv/build/lib/python3.10/site-packages/setuptools/command/sdist.py", line 126, in <genexpr>
          files = (c.get_source_files() for c in cmds if hasattr(c, "get_source_files"))
        File "/home/spksrc/py310.6/spksrc/spk/bazarr/work-x64-6.1/crossenv/build/lib/python3.10/site-packages/setuptools/command/sdist.py", line 125, in <genexpr>
          cmds = (self.get_finalized_command(c) for c in missing_cmds)
        File "/home/spksrc/py310.6/spksrc/spk/bazarr/work-x64-6.1/crossenv/build/lib/python3.10/site-packages/setuptools/_distutils/cmd.py", line 306, in get_finalized_command
          cmd_obj.ensure_finalized()
        File "/home/spksrc/py310.6/spksrc/spk/bazarr/work-x64-6.1/crossenv/build/lib/python3.10/site-packages/setuptools/_distutils/cmd.py", line 109, in ensure_finalized
          self.finalize_options()
        File "/tmp/pip-wheel-zx645048/numpy_62d5a1a8355144f781d4c843ede91f36/numpy/distutils/command/config_compiler.py", line 69, in finalize_options
          v = getattr(c, a)
        File "/home/spksrc/py310.6/spksrc/spk/bazarr/work-x64-6.1/crossenv/build/lib/python3.10/site-packages/Cython/Distutils/old_build_ext.py", line 157, in __getattr__
          return _build_ext.build_ext.__getattr__(self, name)
        File "/home/spksrc/py310.6/spksrc/spk/bazarr/work-x64-6.1/crossenv/build/lib/python3.10/site-packages/setuptools/_distutils/cmd.py", line 105, in __getattr__
          raise AttributeError(attr)
      AttributeError: fcompiler. Did you mean: 'compiler'?
      [end of output]
  
  note: This error originates from a subprocess, and is likely not a problem with pip.
error: metadata-generation-failed

× Encountered error while generating package metadata.
╰─> See above for output.

note: This is an issue with the package mentioned above, not pip.
hint: See above for details.
make[3]: *** [../../mk/spksrc.wheel.mk:139: cross-compile-wheel-numpy] Error 1
make[3]: Leaving directory '/home/spksrc/py310.6/spksrc/spk/bazarr'
make[2]: *** [../../mk/spksrc.wheel.mk:81: build_wheel_target] Error 1
make[2]: Leaving directory '/home/spksrc/py310.6/spksrc/spk/bazarr'
make[1]: *** [../../mk/spksrc.spk.mk:603: build-arch-x64-6.1] Error 1
make[1]: Leaving directory '/home/spksrc/py310.6/spksrc/spk/bazarr'
make: *** [../../mk/spksrc.spk.mk:597: arch-x64-6.1] Error 2

...

Posted by Wei on 2023-04-06, Last Modified on 2025-08-11

Via `.gitconfig`

Globally

So, for example if your proxy server configuration is as follows:

Server: myproxyserver
Port: 8080
Username: mydomain\myusername
Password: mypassword

...

Posted by Wei on 2023-04-03, Last Modified on 2025-08-11

【Golang】泛型（Generics）

...

Posted by Wei on 2023-04-02, Last Modified on 2025-08-11

Undo Logs

An undo log is a collection of undo log records associated with a single read-write transaction. An undo log record contains information about how to undo the latest change by a transaction to a clustered index record. If another transaction needs to see the original data as part of a consistent read operation, the unmodified data is retrieved from undo log records. Undo logs exist within undo log segments, which are contained within rollback segments. Rollback segments reside in undo tablespaces and in the global temporary tablespace.

Undo logs that reside in the global temporary tablespace are used for transactions that modify data in user-defined temporary tables. These undo logs are not redo-logged, as they are not required for crash recovery. They are used only for rollback while the server is running. This type of undo log benefits performance by avoiding redo logging I/O.

...

Posted by Wei on 2023-03-29, Last Modified on 2025-08-11

【Database】Write-ahead Logging (Redo Logs)

Write-Ahead Logging (WAL)

Write-Ahead Logging (WAL) is a standard method for ensuring data integrity. A detailed description can be found in most (if not all) books about transaction processing. Briefly, WAL’s central concept is that changes to data files (where tables and indexes reside) must be written only after those changes have been logged, that is, after log records describing the changes have been flushed to permanent storage. If we follow this procedure, we do not need to flush data pages to disk on every transaction commit, because we know that in the event of a crash we will be able to recover the database using the log: any changes that have not been applied to the data pages can be redone from the log records. (This is roll-forward recovery, also known as REDO.)

...

Posted by Wei on 2023-03-29, Last Modified on 2025-08-11

Two-phase Commit in MySQL

The two-phase commit in MySQL is not a two-phase commit of a distributed transaction, but a two-phase commit between redo and Binlog after the Binlog is turned on.

Overall, two-phase commit:

prepare phase - call MYSQL_BIN_LOG::prepare
1. redo log prepare - innobase_xa_prepare, i.e., the transaction is fully recorded in the redo log and syncs the redo log file to disk (as necessary)

commit phase
1. innodb释放锁，释放回滚段，设置提交状态
2. write Binlog- call MYSQL_BIN_LOG::commit
3. redo log commit - innobase_commit

...

Posted by Wei on 2023-03-27, Last Modified on 2025-08-11

西维蜀黍

【Concurrent Control】MVCC

Multiversion concurrency control (MVCC)

【macOS】搜索不出来存在的文件

【Python】pip 安装 numpy 失败

Context

【Git】设置代理

Via `.gitconfig`

Globally

【Golang】泛型（Generics）

【MySQL】Logs - Undo Logs

Undo Logs

【Database】Write-ahead Logging (Redo Logs)

Write-Ahead Logging (WAL)

【Kafka】Transactional Messages

【Kafka】Exactly Once

【MySQL】MySQL 中的两阶段提交

Two-phase Commit in MySQL

FEATURED TAGS

ABOUT ME

FRIENDS

【Concurrent Control】MVCC

Multiversion concurrency control (MVCC)

【macOS】搜索不出来存在的文件

【Python】pip 安装 numpy 失败

Context

【Git】设置代理

Via .gitconfig

Globally

【Golang】泛型（Generics）

【MySQL】Logs - Undo Logs

Undo Logs

【Database】Write-ahead Logging (Redo Logs)

Write-Ahead Logging (WAL)

【Kafka】Transactional Messages

【Kafka】Exactly Once

【MySQL】MySQL 中的两阶段提交

Two-phase Commit in MySQL

FEATURED TAGS

ABOUT ME

FRIENDS

Via `.gitconfig`