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| author | Bruce Momjian <bruce@momjian.us> | 2014-02-13 21:45:57 -0500 |
|---|---|---|
| committer | Bruce Momjian <bruce@momjian.us> | 2014-02-13 21:46:03 -0500 |
| commit | 9c57d11fca3b87daa741151f75085e2554ee310f (patch) | |
| tree | fa758dff39785f5960a3656b72384253ccfca3eb /src/backend/utils/adt/varchar.c | |
| parent | b8f00a46bc4ae77c09f4564f3b3c675fb9e51974 (diff) | |
| download | postgresql-9c57d11fca3b87daa741151f75085e2554ee310f.tar.gz postgresql-9c57d11fca3b87daa741151f75085e2554ee310f.zip | |
Add C comment about problems with CHAR() space trimming
Diffstat (limited to 'src/backend/utils/adt/varchar.c')
| -rw-r--r-- | src/backend/utils/adt/varchar.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/src/backend/utils/adt/varchar.c b/src/backend/utils/adt/varchar.c index 502ca44e04a..284b5d13093 100644 --- a/src/backend/utils/adt/varchar.c +++ b/src/backend/utils/adt/varchar.c @@ -846,6 +846,18 @@ bpcharcmp(PG_FUNCTION_ARGS) len2; int cmp; + /* + * Trimming trailing spaces off of both strings can cause a string + * with a character less than a space to compare greater than a + * space-extended string, e.g. this returns false: + * SELECT E'ab\n'::CHAR(10) < E'ab '::CHAR(10); + * even though '\n' is less than the space if CHAR(10) was + * space-extended. The correct solution would be to trim only + * the longer string to be the same length of the shorter, if + * possible, then do the comparison. However, changing this + * might break existing indexes, breaking binary upgrades. + * For details, see http://www.postgresql.org/message-id/CAK+WP1xdmyswEehMuetNztM4H199Z1w9KWRHVMKzyyFM+hV=zA@mail.gmail.com + */ len1 = bcTruelen(arg1); len2 = bcTruelen(arg2); |