Bug #1313 EXPLAIN gives wrong number of read records in case of FULL SCAN
| Submitted: | 16 Sep 2003 15:18 | Modified: | 27 Sep 2008 9:07 |
|---|---|---|---|
| Reporter: | Konstantin Osipov (OCA) | Email Updates: | |
| Status: | Can't repeat | Impact on me: | |
| Category: | MySQL Server | Severity: | S3 (Non-critical) |
| Version: | All | OS: | Any (All) |
| Assigned to: | Konstantin Osipov | CPU Architecture: | Any |
[27 Sep 2008 9:07]
Konstantin Osipov
Somehow this got fixed.
mysql> explain select t1.*,t2.* from t1,t1 as t2 where t1.A=t2.B\G
*************************** 1. row ***************************
id: 1
select_type: SIMPLE
table: t1
type: ALL
possible_keys: a
key: NULL
key_len: NULL
ref: NULL
rows: 5
Extra:
*************************** 2. row ***************************
id: 1
select_type: SIMPLE
table: t2
type: ALL
possible_keys: b
key: NULL
key_len: NULL
ref: NULL
rows: 5
Extra: Using where; Using join buffer
2 rows in set (0.00 sec)
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Description: CREATE TABLE t1 ( a char(5) NOT NULL, b char(4) NOT NULL, KEY (a), KEY (b) ); INSERT INTO t1 VALUES ('A','B'),('b','A'),('C','c'),('D','E'),('a','a'); explain select t1.*,t2.* from t1,t1 as t2 where t1.A=t2.B; explain prints:*************************** 1. row *************************** table: t1 type: ALL possible_keys: a key: NULL key_len: NULL ref: NULL rows: 5 Extra: *************************** 2. row *************************** table: t2 type: ALL possible_keys: b key: NULL key_len: NULL ref: NULL rows: 4 Number of rows for t2 should be equal count(*) from t2 (= 5) How to repeat: see description Suggested fix: Fix explain support