diff options
| author | Michael Paquier | 2024-07-23 07:54:51 +0000 |
|---|---|---|
| committer | Michael Paquier | 2024-07-23 07:54:51 +0000 |
| commit | ffb0603929617f39d449e942abe96cdba36e7545 (patch) | |
| tree | d2c4086871cf93d0d0c5accaa84b935b53666680 | |
| parent | 65504b747f3c217dfa91297db6ea219924a3fa8a (diff) | |
Improve comments in slru.{c,h} about segment name format
slru.h described incorrectly how SLRU segment names are formatted
depending on the segment number and if long or short segment names are
used. This commit closes the gap with a better description, fitting
with the reality.
Reported-by: Noah Misch
Author: Aleksander Alekseev
Discussion: https://postgr.es/m/[email protected]
Backpatch-through: 17
| -rw-r--r-- | src/backend/access/transam/slru.c | 15 | ||||
| -rw-r--r-- | src/include/access/slru.h | 7 |
2 files changed, 18 insertions, 4 deletions
diff --git a/src/backend/access/transam/slru.c b/src/backend/access/transam/slru.c index 77b05cc0a74..248aa1a6553 100644 --- a/src/backend/access/transam/slru.c +++ b/src/backend/access/transam/slru.c @@ -72,6 +72,21 @@ #include "storage/shmem.h" #include "utils/guc_hooks.h" +/* + * Converts segment number to the filename of the segment. + * + * "path" should point to a buffer at least MAXPGPATH characters long. + * + * If ctl->long_segment_names is true, segno can be in the range [0, 2^60-1]. + * The resulting file name is made of 15 characters, e.g. dir/123456789ABCDEF. + * + * If ctl->long_segment_names is false, segno can be in the range [0, 2^24-1]. + * The resulting file name is made of 4 to 6 characters, as of: + * + * dir/1234 for [0, 2^16-1] + * dir/12345 for [2^16, 2^20-1] + * dir/123456 for [2^20, 2^24-1] + */ static inline int SlruFileName(SlruCtl ctl, char *path, int64 segno) { diff --git a/src/include/access/slru.h b/src/include/access/slru.h index 8a8d1918733..97e612cd100 100644 --- a/src/include/access/slru.h +++ b/src/include/access/slru.h @@ -134,10 +134,9 @@ typedef struct SlruCtlData bits16 bank_mask; /* - * If true, use long segment filenames formed from lower 48 bits of the - * segment number, e.g. pg_xact/000000001234. Otherwise, use short - * filenames formed from lower 16 bits of the segment number e.g. - * pg_xact/1234. + * If true, use long segment file names. Otherwise, use short file names. + * + * For details about the file name format, see SlruFileName(). */ bool long_segment_names; |