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| author | Jimmy Yang <jimmy.yang@oracle.com> | 2011-01-14 09:02:28 -0800 |
|---|---|---|
| committer | Jimmy Yang <jimmy.yang@oracle.com> | 2011-01-14 09:02:28 -0800 |
| commit | 9cd4d4984025857782e12e53d32cea5e4b7684e5 (patch) | |
| tree | 91674b9ab3c48997806024be85f5a431ad47574b /storage/innobase/rem | |
| parent | 634fe860562f7249c55a0f946a1fb50972b9f9ff (diff) | |
| download | mariadb-git-9cd4d4984025857782e12e53d32cea5e4b7684e5.tar.gz | |
Fix Bug#30423 "InnoDBs treatment of NULL in index stats causes bad
"rows examined" estimates". This change implements "innodb_stats_method"
with options of "nulls_equal", "nulls_unequal" and "null_ignored".
rb://553 approved by Marko
Diffstat (limited to 'storage/innobase/rem')
| -rw-r--r-- | storage/innobase/rem/rem0cmp.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/storage/innobase/rem/rem0cmp.c b/storage/innobase/rem/rem0cmp.c index ca0ec663548..2939c119e2e 100644 --- a/storage/innobase/rem/rem0cmp.c +++ b/storage/innobase/rem/rem0cmp.c @@ -720,6 +720,10 @@ cmp_rec_rec_with_match( const ulint* offsets1,/* in: rec_get_offsets(rec1, index) */ const ulint* offsets2,/* in: rec_get_offsets(rec2, index) */ dict_index_t* index, /* in: data dictionary index */ + ibool nulls_unequal, + /* in: TRUE if this is for index statistics + cardinality estimation, and innodb_stats_method + is "nulls_unequal" or "nulls_ignored" */ ulint* matched_fields, /* in/out: number of already completely matched fields; when the function returns, contains the value the for current @@ -821,9 +825,13 @@ cmp_rec_rec_with_match( || rec2_f_len == UNIV_SQL_NULL) { if (rec1_f_len == rec2_f_len) { - - goto next_field; - + /* This is limited to stats collection, + cannot use it for regular search */ + if (nulls_unequal) { + ret = -1; + } else { + goto next_field; + } } else if (rec2_f_len == UNIV_SQL_NULL) { /* We define the SQL null to be the |