Postgresql 中文操作指南
pg_test_fsync
pg_test_fsync — 为 PostgreSQL 确定最快的 wal_sync_method
pg_test_fsync — determine fastest wal_sync_method for PostgreSQL
Description
pg_test_fsync 的目的是让用户对特定系统上最快的 wal_sync_method 有合理的了解，并且在确定了 I/O 问题时提供诊断信息。然而，pg_test_fsync 所显示的差异在真实的数据库处理能力方面可能没有任何显著差别，特别是因为很多数据库服务器不会因其预写日志而受到速度限制。pg_test_fsync 为每个 wal_sync_method 报告文件同步操作的平均时间（以微秒为单位），它也可用于告知针对优化 commit_delay 值所做的尝试。
pg_test_fsync is intended to give you a reasonable idea of what the fastest wal_sync_method is on your specific system, as well as supplying diagnostic information in the event of an identified I/O problem. However, differences shown by pg_test_fsync might not make any significant difference in real database throughput, especially since many database servers are not speed-limited by their write-ahead logs. pg_test_fsync reports average file sync operation time in microseconds for each wal_sync_method, which can also be used to inform efforts to optimize the value of commit_delay.
Options
pg_test_fsync 接受以下命令行选项：
pg_test_fsync accepts the following command-line options:
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-f_—filename_
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Specifies the file name to write test data in. This file should be in the same file system that the pg_wal directory is or will be placed in. (pg_wal contains the WAL files.) The default is pg_test_fsync.out in the current directory.
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-s_—secs-per-test_
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Specifies the number of seconds for each test. The more time per test, the greater the test’s accuracy, but the longer it takes to run. The default is 5 seconds, which allows the program to complete in under 2 minutes.
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-V_—version_
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Print the pg_test_fsync version and exit.
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-?_—help_
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Show help about pg_test_fsync command line arguments, and exit.
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