Bug #5304 | Cluster: index cardinality isn't the same as with MyISAM/InnoDB | ||
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Submitted: | 30 Aug 2004 22:53 | Modified: | 1 Oct 2004 13:30 |
Reporter: | Trudy Pelzer | Email Updates: | |
Status: | Closed | Impact on me: | |
Category: | MySQL Cluster: Cluster (NDB) storage engine | Severity: | S3 (Non-critical) |
Version: | 4.1.4-gamma (ndb) | OS: | Linux (SuSE 9.1) |
Assigned to: | Martin Skold | CPU Architecture: | Any |
[30 Aug 2004 22:53]
Trudy Pelzer
[31 Aug 2004 5:26]
MySQL Verification Team
Thank you for the bug report: mysql> show index from tmyisam\G *************************** 1. row *************************** Table: tmyisam Non_unique: 0 Key_name: PRIMARY Seq_in_index: 1 Column_name: col1 Collation: A Cardinality: 2 Sub_part: NULL Packed: NULL Null: Index_type: BTREE Comment: 1 row in set (0.00 sec) mysql> show index from tndb\G *************************** 1. row *************************** Table: tndb Non_unique: 0 Key_name: PRIMARY Seq_in_index: 1 Column_name: col1 Collation: NULL Cardinality: NULL Sub_part: NULL Packed: NULL Null: Index_type: BTREE Comment: 1 row in set (0.00 sec)
[1 Oct 2004 13:29]
Martin Skold
Index cardinality for primary key is fixed to be the number of rows. Cardinality for other indexes is an estimation and different storage engines estimate differently, with the aim of getting good query plans. This will have to be investigated further for ndbcluster.