* filer: skip COLLATE "C" list fallback on CockroachDB
CockroachDB string comparison is already byte-ordered, so wrapping the
list queries in COLLATE "C" can never change result order. It reports
datcollate=en_US.utf8 regardless of how the database was created, so the
collation check always misfires and forces the fallback. On 22.1 and
older COLLATE "C" is rejected as an invalid locale, turning every filer
list query into a hard failure. Detect the backend via version() and
keep the default ordering.
* filer: test CockroachDB collation detection
Cover the CockroachDB skip path and the locale-aware Postgres force path
with go-sqlmock.
* mysql: keep S3 list order byte-lexicographic regardless of name column collation
ORDER BY name and the name > ? pagination predicate follow the column
collation, so a case-insensitive filemeta.name (e.g. utf8mb3_general_ci)
returns S3 keys out of byte order and breaks clients that merge two sorted
listings.
Detect the live name collation at startup; only when it isn't binary, wrap
the list comparison, prefix, and ORDER BY in BINARY name so order and
pagination stay consistent. Correctly configured utf8mb4_bin tables keep
their indexed range scan unchanged, and the operator gets a warning to
convert the column.
* postgres: keep S3 list order byte-lexicographic regardless of name column collation
ORDER BY name and the name > $n pagination predicate follow the column or
database collation, so a locale-aware filemeta.name (e.g. the en_US.UTF-8
database default) returns S3 keys out of byte order and breaks clients that
merge two sorted listings.
Detect the live name collation at startup; only when it isn't byte-ordered,
wrap the list comparison, prefix, and ORDER BY in COLLATE "C" so order and
pagination stay consistent. A byte-ordered (C/POSIX/C.UTF-8) column keeps its
indexed range scan unchanged, and the operator gets a warning to declare the
column COLLATE "C".
Chris Lu