From 60f566b4f24362f54003569d5f6e24137bcd83fc Mon Sep 17 00:00:00 2001 From: Andres Freund Date: Tue, 1 Apr 2025 13:30:33 -0400 Subject: aio: Add pg_aios view The new view lists all IO handles that are currently in use and is mainly useful for PG developers, but may also be useful when tuning PG. Bumps catversion. Reviewed-by: Noah Misch Discussion: https://postgr.es/m/uvrtrknj4kdytuboidbhwclo4gxhswwcpgadptsjvjqcluzmah%40brqs62irg4dt --- doc/src/sgml/system-views.sgml | 294 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 294 insertions(+) (limited to 'doc/src') diff --git a/doc/src/sgml/system-views.sgml b/doc/src/sgml/system-views.sgml index 3f5a306247e..e9a59af8c34 100644 --- a/doc/src/sgml/system-views.sgml +++ b/doc/src/sgml/system-views.sgml @@ -51,6 +51,11 @@ + + pg_aios + In-use asynchronous IO handles + + pg_available_extensions available extensions @@ -231,6 +236,295 @@ + + <structname>pg_aios</structname> + + + pg_aios + + + + The pg_aios view lists all handles that are currently in-use. An I/O handle + is used to reference an I/O operation that is being prepared, executed or + is in the process of completing. pg_aios contains + one row for each I/O handle. + + + + This view is mainly useful for developers of + PostgreSQL, but may also be useful when tuning + PostgreSQL. + + + + <structname>pg_aios</structname> Columns + + + + + Column Type + + + Description + + + + + + + + pid int4 + + + Process ID of the server process that is issuing this I/O. + + + + + + io_id int4 + + + Identifier of the I/O handle. Handles are reused once the I/O + completed (or if the handle is released before I/O is started). On reuse + + pg_aios.io_generation + + is incremented. + + + + + + io_generation int8 + + + Generation of the I/O handle. + + + + + + state text + + + State of the I/O handle: + + + + HANDED_OUT, referenced by code but not yet used + + + + + DEFINED, information necessary for execution is known + + + + + STAGED, ready for execution + + + + + SUBMITTED, submitted for execution + + + + + COMPLETED_IO, finished, but result has not yet been processed + + + + + COMPLETED_SHARED, shared completion processing completed + + + + + COMPLETED_LOCAL, backend local completion processing completed + + + + + + + + + operation text + + + Operation performed using the I/O handle: + + + + invalid, not yet known + + + + + readv, a vectored read + + + + + writev, a vectored write + + + + + + + + + off int8 + + + Offset of the I/O operation. + + + + + + length int8 + + + Length of the I/O operation. + + + + + + target text + + + What kind of object is the I/O targeting: + + + + smgr, I/O on relations + + + + + + + + + handle_data_len int2 + + + Length of the data associated with the I/O operation. For I/O to/from + and , this indicates the number of buffers the + I/O is operating on. + + + + + + raw_result int4 + + + Low-level result of the I/O operation, or NULL if the operation has not + yet completed. + + + + + + result text + + + High-level result of the I/O operation: + + + + UNKNOWN means that the result of the + operation is not yet known. + + + + + OK means the I/O completed successfully. + + + + + PARTIAL means that the I/O completed without + error, but did not process all data. Commonly callers will need to + retry and perform the remainder of the work in a separate I/O. + + + + + WARNING means that the I/O completed without + error, but that execution of the IO triggered a warning. E.g. when + encountering a corrupted buffer with enabled. + + + + + ERROR means the I/O failed with an error. + + + + + + + + + target_desc text + + + Description of what the I/O operation is targeting. + + + + + + f_sync bool + + + Flag indicating whether the I/O is executed synchronously. + + + + + + f_localmem bool + + + Flag indicating whether the I/O references process local memory. + + + + + + f_buffered bool + + + Flag indicating whether the I/O is buffered I/O. + + + + + +
+ + + The pg_aios view is read-only. + + + + By default, the pg_aios view can be read only by + superusers or roles with privileges of the + pg_read_all_stats role. + + + <structname>pg_available_extensions</structname> -- cgit v1.2.3