How InnoDB flush the log buffer

When InnoDB flush the log buffer to the log file on disk, it locks the buffer with a mutex, flushes up it to a desired point, and then moves any remaining entries to the front of the buffer.

If you care more about performance than durability, you can change innodb_flush_log_at_trx_commit to control where and how often the log buffer is flushed.

0: write the log buffer to the log file and flush the log file every second, and do nothing at transaction commit.

1:write the log buffer to the log file and flush it to durable storage every time a transaction commits.

2: write the log buffer to the log file at every commit, but do not flush it.

In most operating systems, writing the buffer to the log simply moves the data from InnoDB’s memory buffer to the operating system’s cache, which is also in memory.

In contrast, flushing the log to durable storage means InnoDB asks the operating system to flush the data out of the cache and ensure it is written to the disk.

Sometime the disk controller or operating system can fask flush by put the data to yet another cache.

Setting innodb_flush_log_at_trx_commit anything other than 1 can cause you to lose transactions.

the best configuration for high performance transactional needs is to leave innodb_flush_log_at_trx_commit set to 1 and place the log files on a raid volumn backed by a battery backed cache.

PErconer Server extends … to make is a per-session variable, instead of global for a whole server.

# Other default tuning values # MySQL Server Instance Configuration File # ---------------------------------------------------------------------- # Generated by the MySQL Server Instance Configuration Wizard # # # Installation Instructions # ---------------------------------------------------------------------- # # On Linux you can copy this file to /etc/my.cnf to set global options, # mysql-data-dir/my.cnf to set server-specific options # (@localstatedir@ for this installation) or to # ~/.my.cnf to set user-specific options. # # On Windows, when MySQL has been installed using MySQL Installer you # should keep this file in the ProgramData directory of your server # (e.g. C:\ProgramData\MySQL\MySQL Server X.Y). To make sure the server # reads the config file, use the startup option "--defaults-file". # # To run the server from the command line, execute this in a # command line shell, e.g. # mysqld --defaults-file="C:\Program Files\MySQL\MySQL Server X.Y\my.ini" # # To install the server as a Windows service manually, execute this in a # command line shell, e.g. # mysqld --install MySQLXY --defaults-file="C:\Program Files\MySQL\MySQL Server X.Y\my.ini" # # And then execute this in a command line shell to start the server, e.g. # net start MySQLXY # # # Guidelines for editing this file # ---------------------------------------------------------------------- # # In this file, you can use all long options that the program supports. # If you want to know the options a program supports, start the program # with the "--help" option. # # More detailed information about the individual options can also be # found in the manual. # # For advice on how to change settings please see # https://dev.mysql.com/doc/refman/8.0/en/server-configuration-defaults.html # # # CLIENT SECTION # ---------------------------------------------------------------------- # # The following options will be read by MySQL client applications. # Note that only client applications shipped by MySQL are guaranteed # to read this section. If you want your own MySQL client program to # honor these values, you need to specify it as an option during the # MySQL client library initialization. # [client] # pipe= # socket=MYSQL port=3306 [mysql] no-beep # default-character-set= # SERVER SECTION # ---------------------------------------------------------------------- # # The following options will be read by the MySQL Server. Make sure that # you have installed the server correctly (see above) so it reads this # file. # [mysqld] port = 3306 bind-address = 0.0.0.0 # The next three options are mutually exclusive to SERVER_PORT below. # skip-networking # enable-named-pipe # shared-memory # shared-memory-base-name=MYSQL # The Pipe the MySQL Server will use. # socket=MYSQL # The access control granted to clients on the named pipe created by the MySQL Server. # named-pipe-full-access-group= # The TCP/IP Port the MySQL Server will listen on port=3306 # Path to installation directory. All paths are usually resolved relative to this. # basedir="D:/mysql" # Path to the database root datadir=D:/mysql\Data # The default character set that will be used when a new schema or table is # created and no character set is defined # character-set-server= # The default storage engine that will be used when create new tables when default-storage-engine=INNODB # The current server SQL mode, which can be set dynamically. # Modes affect the SQL syntax MySQL supports and the data validation checks it performs. This # makes it easier to use MySQL in different environments and to use MySQL together with other # database servers. sql-mode="ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_ENGINE_SUBSTITUTION" # General and Slow logging. log-output=FILE general-log=0 general_log_file="WIN-20240617SLP.log" slow-query-log=1 slow_query_log_file="WIN-20240617SLP-slow.log" long_query_time=10 # Error Logging. log-error="WIN-20240617SLP.err" # ***** Group Replication Related ***** # Specifies the base name to use for binary log files. With binary logging # enabled, the server logs all statements that change data to the binary # log, which is used for backup and replication. log-bin="WIN-20240617SLP-bin" # ***** Group Replication Related ***** # Specifies the server ID. For servers that are used in a replication topology, # you must specify a unique server ID for each replication server, in the # range from 1 to 2^32 − 1. "Unique" means that each ID must be different # from every other ID in use by any other source or replica. server-id=1 # Indicates how table and database names are stored on disk and used in MySQL. # Value 0 = Table and database names are stored on disk using the lettercase specified in the CREATE # TABLE or CREATE DATABASE statement. Name comparisons are case-sensitive. You should not # set this variable to 0 if you are running MySQL on a system that has case-insensitive file # names (such as Windows or macOS). If you force this variable to 0 with # --lower-case-table-names=0 on a case-insensitive file system and access MyISAM tablenames # using different lettercases, index corruption may result. # Value 1 = Table names are stored in lowercase on disk and name comparisons are not case-sensitive. # MySQL converts all table names to lowercase on storage and lookup. This behavior also applies # to database names and table aliases. # Value 2 = Table and database names are stored on disk using the lettercase specified in the CREATE TABLE # or CREATE DATABASE statement, but MySQL converts them to lowercase on lookup. Name comparisons # are not case-sensitive. This works only on file systems that are not case-sensitive! InnoDB # table names and view names are stored in lowercase, as for lower_case_table_names=1. lower_case_table_names=1 # This variable is used to limit the effect of data import and export operations, such as # those performed by the LOAD DATA and SELECT ... INTO OUTFILE statements and the # LOAD_FILE() function. These operations are permitted only to users who have the FILE privilege. secure-file-priv="D:/mysql/Uploads" # The maximum amount of concurrent sessions the MySQL server will # allow. One of these connections will be reserved for a user with # SUPER privileges to allow the administrator to login even if the # connection limit has been reached. max_connections=151 # The number of open tables for all threads. Increasing this value increases the number # of file descriptors that mysqld requires. table_open_cache=4000 # Defines the maximum amount of memory that can be occupied by the TempTable # storage engine before it starts storing data on disk. temptable_max_ram=1G # Defines the maximum size of internal in-memory temporary tables created # by the MEMORY storage engine and, as of MySQL 8.0.28, the TempTable storage # engine. If an internal in-memory temporary table exceeds this size, it is # automatically converted to an on-disk internal temporary table. tmp_table_size=128M # The storage engine for in-memory internal temporary tables (see Section 8.4.4, "Internal # Temporary Table Use in MySQL"). Permitted values are TempTable (the default) and MEMORY. internal_tmp_mem_storage_engine=TempTable #*** MyISAM Specific options # The maximum size of the temporary file that MySQL is permitted to use while re-creating a # MyISAM index (during REPAIR TABLE, ALTER TABLE, or LOAD DATA). If the file size would be # larger than this value, the index is created using the key cache instead, which is slower. # The value is given in bytes. myisam_max_sort_file_size=2146435072 # The size of the buffer that is allocated when sorting MyISAM indexes during a REPAIR TABLE # or when creating indexes with CREATE INDEX or ALTER TABLE. myisam_sort_buffer_size=245M # Size of the Key Buffer, used to cache index blocks for MyISAM tables. # Do not set it larger than 30% of your available memory, as some memory # is also required by the OS to cache rows. Even if you're not using # MyISAM tables, you should still set it to 8-64M as it will also be # used for internal temporary disk tables. key_buffer_size=8M # Each thread that does a sequential scan for a MyISAM table allocates a buffer # of this size (in bytes) for each table it scans. If you do many sequential # scans, you might want to increase this value, which defaults to 131072. The # value of this variable should be a multiple of 4KB. If it is set to a value # that is not a multiple of 4KB, its value is rounded down to the nearest multiple # of 4KB. read_buffer_size=128K # This variable is used for reads from MyISAM tables, and, for any storage engine, # for Multi-Range Read optimization. read_rnd_buffer_size=256K #*** INNODB Specific options *** # innodb_data_home_dir= # Use this option if you have a MySQL server with InnoDB support enabled # but you do not plan to use it. This will save memory and disk space # and speed up some things. # skip-innodb # If set to 1, InnoDB will flush (fsync) the transaction logs to the # disk at each commit, which offers full ACID behavior. If you are # willing to compromise this safety, and you are running small # transactions, you may set this to 0 or 2 to reduce disk I/O to the # logs. Value 0 means that the log is only written to the log file and # the log file flushed to disk approximately once per second. Value 2 # means the log is written to the log file at each commit, but the log # file is only flushed to disk approximately once per second. innodb_flush_log_at_trx_commit=1 # The size in bytes of the buffer that InnoDB uses to write to the log files on # disk. The default value changed from 8MB to 16MB with the introduction of 32KB # and 64KB innodb_page_size values. A large log buffer enables large transactions # to run without the need to write the log to disk before the transactions commit. # Thus, if you have transactions that update, insert, or delete many rows, making # the log buffer larger saves disk I/O. innodb_log_buffer_size=16M # The size in bytes of the buffer pool, the memory area where InnoDB caches table # and index data. The default value is 134217728 bytes (128MB). The maximum value # depends on the CPU architecture; the maximum is 4294967295 (232-1) on 32-bit systems # and 18446744073709551615 (264-1) on 64-bit systems. On 32-bit systems, the CPU # architecture and operating system may impose a lower practical maximum size than the # stated maximum. When the size of the buffer pool is greater than 1GB, setting # innodb_buffer_pool_instances to a value greater than 1 can improve the scalability on # a busy server. innodb_buffer_pool_size=128M # Defines the amount of disk space occupied by redo log files. This variable supersedes the # innodb_log_files_in_group and innodb_log_file_size variables. innodb_redo_log_capacity=100M # Defines the maximum number of threads permitted inside of InnoDB. A value # of 0 (the default) is interpreted as infinite concurrency (no limit). This # variable is intended for performance tuning on high concurrency systems. # InnoDB tries to keep the number of threads inside InnoDB less than or equal to # the innodb_thread_concurrency limit. Once the limit is reached, additional threads # are placed into a "First In, First Out" (FIFO) queue for waiting threads. Threads # waiting for locks are not counted in the number of concurrently executing threads. innodb_thread_concurrency=25 # The increment size (in MB) for extending the size of an auto-extend InnoDB system tablespace file when it becomes full. innodb_autoextend_increment=64 # The number of regions that the InnoDB buffer pool is divided into. # For systems with buffer pools in the multi-gigabyte range, dividing the buffer pool into separate instances can improve concurrency, # by reducing contention as different threads read and write to cached pages. innodb_buffer_pool_instances=8 # Determines the number of threads that can enter InnoDB concurrently. innodb_concurrency_tickets=5000 # Specifies how long in milliseconds (ms) a block inserted into the old sublist must stay there after its first access before # it can be moved to the new sublist. innodb_old_blocks_time=1000 # When this variable is enabled, InnoDB updates statistics during metadata statements. innodb_stats_on_metadata=0 # When innodb_file_per_table is enabled (the default in 5.6.6 and higher), InnoDB stores the data and indexes for each newly created table # in a separate .ibd file, rather than in the system tablespace. innodb_file_per_table=1 # Use the following list of values: 0 for crc32, 1 for strict_crc32, 2 for innodb, 3 for strict_innodb, 4 for none, 5 for strict_none. innodb_checksum_algorithm=0 # If this is set to a nonzero value, all tables are closed every flush_time seconds to free up resources and # synchronize unflushed data to disk. # This option is best used only on systems with minimal resources. flush_time=0 # The minimum size of the buffer that is used for plain index scans, range index scans, and joins that do not use # indexes and thus perform full table scans. join_buffer_size=256K # The maximum size of one packet or any generated or intermediate string, or any parameter sent by the # mysql_stmt_send_long_data() C API function. max_allowed_packet=64M # If more than this many successive connection requests from a host are interrupted without a successful connection, # the server blocks that host from performing further connections. max_connect_errors=100 # The number of file descriptors available to mysqld from the operating system # Try increasing the value of this option if mysqld gives the error "Too many open files". open_files_limit=8161 # If you see many sort_merge_passes per second in SHOW GLOBAL STATUS output, you can consider increasing the # sort_buffer_size value to speed up ORDER BY or GROUP BY operations that cannot be improved with query optimization # or improved indexing. sort_buffer_size=256K # Specify the maximum size of a row-based binary log event, in bytes. # Rows are grouped into events smaller than this size if possible. The value should be a multiple of 256. binlog_row_event_max_size=8K # If the value of this variable is greater than 0, a replica synchronizes its master.info file to disk. # (using fdatasync()) after every sync_source_info events. sync_source_info=10000 # If the value of this variable is greater than 0, the MySQL server synchronizes its relay log to disk. # (using fdatasync()) after every sync_relay_log writes to the relay log. sync_relay_log=10000 # Load mysql plugins at start."plugin_x ; plugin_y". # plugin_load # The TCP/IP Port the MySQL Server X Protocol will listen on. 这就是配置文件内容
10-03
2025-09-15T08:21:09.471534Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details). 2025-09-15T08:21:09.471574Z 0 [Warning] 'NO_ZERO_DATE', 'NO_ZERO_IN_DATE' and 'ERROR_FOR_DIVISION_BY_ZERO' sql modes should be used with strict mode. They will be merged with strict mode in a future release. 2025-09-15T08:21:09.732610Z 0 [Warning] InnoDB: New log files created, LSN=45790 2025-09-15 16:21:09 0xe5c InnoDB: Assertion failure in thread 3676 in file fsp0fsp.cc line 3301 InnoDB: Failing assertion: !is_system_tablespace(space->id) InnoDB: We intentionally generate a memory trap. InnoDB: Submit a detailed bug report to http://bugs.mysql.com. InnoDB: If you get repeated assertion failures or crashes, even InnoDB: immediately after the mysqld startup, there may be InnoDB: corruption in the InnoDB tablespace. Please refer to InnoDB: http://dev.mysql.com/doc/refman/5.7/en/forcing-innodb-recovery.html InnoDB: about forcing recovery. 08:21:09 UTC - mysqld got exception 0x80000003 ; This could be because you hit a bug. It is also possible that this binary or one of the libraries it was linked against is corrupt, improperly built, or misconfigured. This error can also be caused by malfunctioning hardware. Attempting to collect some information that could help diagnose the problem. As this is a crash and something is definitely wrong, the information collection process might fail. key_buffer_size=8388608 read_buffer_size=65536 max_used_connections=0 max_threads=151 thread_count=0 connection_count=0 It is possible that mysqld could use up to key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 58352 K bytes of memory Hope that's ok; if not, decrease some variables in the equation. Thread pointer: 0x0 Attempting backtrace. You can use the following information to find out where mysqld died. If you see no messages after this, something went terribly wrong... 7ff7bf8beeb2 mysqld.exe!my_errno() 7ffc8fbaec9d MSVCR120.dll!raise() 7ffc8fbb4874 MSVCR120.dll!abort() 7ff7bf9da744 mysqld.exe!?reserve@?$vector@EV?$allocator@E@std@@@std@@QEAAX_K@Z() 7ff7bf9f2255 mysqld.exe!?reserve@?$vector@EV?$allocator@E@std@@@std@@QEAAX_K@Z() 7ff7bf9f21f1 mysqld.exe!?reserve@?$vector@EV?$allocator@E@std@@@std@@QEAAX_K@Z() 7ff7bf9ec9d6 mysqld.exe!?reserve@?$vector@EV?$allocator@E@std@@@std@@QEAAX_K@Z() 7ff7bf9ec7d1 mysqld.exe!?reserve@?$vector@EV?$allocator@E@std@@@std@@QEAAX_K@Z() 7ff7bfb15217 mysqld.exe!?reserve@?$vector@EV?$allocator@E@std@@@std@@QEAAX_K@Z() 7ff7bf989b56 mysqld.exe!?reserve@?$vector@EV?$allocator@E@std@@@std@@QEAAX_K@Z() 7ff7bf8f8b00 mysqld.exe!?reserve@?$vector@EV?$allocator@E@std@@@std@@QEAAX_K@Z() 7ff7bf18457e mysqld.exe!?ha_initialize_handlerton@@YAHPEAUst_plugin_int@@@Z() 7ff7bf2806d8 mysqld.exe!?plugin_foreach_with_mask@@YA_NPEAVTHD@@PEAP6AD0PEAUst_plugin_int@@PEAX@ZHI2@Z() 7ff7bf281c40 mysqld.exe!?plugin_register_builtin_and_init_core_se@@YA_NPEAHPEAPEAD@Z() 7ff7bf137303 mysqld.exe!?init_connection_acceptor@?$Connection_acceptor@VShared_mem_listener@@@@QEAA_NXZ() 7ff7bf13c4d5 mysqld.exe!?win_main@@YAHHPEAPEAD@Z() 7ff7bf139cb5 mysqld.exe!?mysql_service@@YAHPEAX@Z() 7ff7bf13a06c mysqld.exe!?mysqld_main@@YAHHPEAPEAD@Z() 7ff7bfc2eef7 mysqld.exe!my_wildcmp_mb() 7ffca5217034 KERNEL32.DLL!BaseThreadInitThunk() 7ffca62bcec1 ntdll.dll!RtlUserThreadStart() The manual page at http://dev.mysql.com/doc/mysql/en/crashing.html contains information that should help you find out what is causing the crash. 2025-09-15T08:25:20.003827Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details). 2025-09-15T08:25:20.003875Z 0 [Warning] 'NO_ZERO_DATE', 'NO_ZERO_IN_DATE' and 'ERROR_FOR_DIVISION_BY_ZERO' sql modes should be used with strict mode. They will be merged with strict mode in a future release. 2025-09-15T08:25:20.016963Z 0 [Note] D:\work\w\sql\mysql\mysql-5.7.29.0\exe\MySQL Server 5.7\bin\mysqld (mysqld 5.7.29-log) starting as process 2468 ... 2025-09-15T08:25:20.020077Z 0 [Note] InnoDB: Mutexes and rw_locks use Windows interlocked functions 2025-09-15T08:25:20.020351Z 0 [Note] InnoDB: Uses event mutexes 2025-09-15T08:25:20.020517Z 0 [Note] InnoDB: _mm_lfence() and _mm_sfence() are used for memory barrier 2025-09-15T08:25:20.020741Z 0 [Note] InnoDB: Compressed tables use zlib 1.2.11 2025-09-15T08:25:20.020936Z 0 [Note] InnoDB: Adjusting innodb_buffer_pool_instances from 8 to 1 since innodb_buffer_pool_size is less than 1024 MiB 2025-09-15T08:25:20.021453Z 0 [Note] InnoDB: Number of pools: 1 2025-09-15T08:25:20.021704Z 0 [Note] InnoDB: Not using CPU crc32 instructions 2025-09-15T08:25:20.022836Z 0 [Note] InnoDB: Initializing buffer pool, total size = 8M, instances = 1, chunk size = 8M 2025-09-15T08:25:20.023428Z 0 [Note] InnoDB: Completed initialization of buffer pool 2025-09-15T08:25:20.040506Z 0 [ERROR] InnoDB: Header page consists of zero bytes in datafile: .\ibdata1, Space ID:0, Flags: 0. Please refer to http://dev.mysql.com/doc/refman/5.7/en/innodb-troubleshooting-datadict.html for how to resolve the issue. 2025-09-15T08:25:20.041009Z 0 [ERROR] InnoDB: Corrupted page [page id: space=0, page number=0] of datafile '.\ibdata1' could not be found in the doublewrite buffer. 2025-09-15T08:25:20.041364Z 0 [ERROR] InnoDB: Plugin initialization aborted with error Data structure corruption 2025-09-15T08:25:20.374320Z 0 [ERROR] Plugin 'InnoDB' init function returned error. 2025-09-15T08:25:20.374601Z 0 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed. 2025-09-15T08:25:20.374824Z 0 [ERROR] Failed to initialize builtin plugins. 2025-09-15T08:25:20.375005Z 0 [ERROR] Aborting 2025-09-15T08:25:20.375139Z 0 [Note] Binlog end 2025-09-15T08:25:20.375322Z 0 [Note] Shutting down plugin 'CSV' 2025-09-15T08:25:20.375648Z 0 [Note] D:\work\w\sql\mysql\mysql-5.7.29.0\exe\MySQL Server 5.7\bin\mysqld: Shutdown complete 2025-09-15T08:25:35.643857Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details). 2025-09-15T08:25:35.643902Z 0 [Warning] 'NO_ZERO_DATE', 'NO_ZERO_IN_DATE' and 'ERROR_FOR_DIVISION_BY_ZERO' sql modes should be used with strict mode. They will be merged with strict mode in a future release. 2025-09-15T08:25:35.644796Z 0 [Note] D:\work\w\sql\mysql\mysql-5.7.29.0\exe\MySQL Server 5.7\bin\mysqld (mysqld 5.7.29-log) starting as process 9380 ... 2025-09-15T08:25:35.647922Z 0 [Note] InnoDB: Mutexes and rw_locks use Windows interlocked functions 2025-09-15T08:25:35.648178Z 0 [Note] InnoDB: Uses event mutexes 2025-09-15T08:25:35.648349Z 0 [Note] InnoDB: _mm_lfence() and _mm_sfence() are used for memory barrier 2025-09-15T08:25:35.648579Z 0 [Note] InnoDB: Compressed tables use zlib 1.2.11 2025-09-15T08:25:35.648778Z 0 [Note] InnoDB: Adjusting innodb_buffer_pool_instances from 8 to 1 since innodb_buffer_pool_size is less than 1024 MiB 2025-09-15T08:25:35.649296Z 0 [Note] InnoDB: Number of pools: 1 2025-09-15T08:25:35.649543Z 0 [Note] InnoDB: Not using CPU crc32 instructions 2025-09-15T08:25:35.650683Z 0 [Note] InnoDB: Initializing buffer pool, total size = 8M, instances = 1, chunk size = 8M 2025-09-15T08:25:35.651269Z 0 [Note] InnoDB: Completed initialization of buffer pool 2025-09-15T08:25:35.665915Z 0 [ERROR] InnoDB: Header page consists of zero bytes in datafile: .\ibdata1, Space ID:0, Flags: 0. Please refer to http://dev.mysql.com/doc/refman/5.7/en/innodb-troubleshooting-datadict.html for how to resolve the issue. 2025-09-15T08:25:35.666408Z 0 [ERROR] InnoDB: Corrupted page [page id: space=0, page number=0] of datafile '.\ibdata1' could not be found in the doublewrite buffer. 2025-09-15T08:25:35.666760Z 0 [ERROR] InnoDB: Plugin initialization aborted with error Data structure corruption 2025-09-15T08:25:35.999666Z 0 [ERROR] Plugin 'InnoDB' init function returned error. 2025-09-15T08:25:35.999965Z 0 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed. 2025-09-15T08:25:36.000286Z 0 [ERROR] Failed to initialize builtin plugins. 2025-09-15T08:25:36.000472Z 0 [ERROR] Aborting 2025-09-15T08:25:36.000611Z 0 [Note] Binlog end 2025-09-15T08:25:36.000797Z 0 [Note] Shutting down plugin 'CSV' 2025-09-15T08:25:36.001116Z 0 [Note] D:\work\w\sql\mysql\mysql-5.7.29.0\exe\MySQL Server 5.7\bin\mysqld: Shutdown complete
09-16
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