CHECK BLOB CHECKSUM checks for and displays columnstore blob file corruptions.

Syntax

CHECK BLOB CHECKSUM [WITH REPAIR[FORCE]];

Arguments

• WITH REPAIR is an option to repair the corruption by either copying the corrupt blob from another partition with a valid copy, or by deleting the metadata for the blob. If the latter occurs, data is lost but the table is queryable again.
• If WITH REPAIR is not included, the output will show how the corruption can be repaired. Repairs that cause data loss will only be done if the FORCE option is included.

Example

This is a simple use showing how the output of CHECK BLOB CHECKSUM displays corruption in columnstore blob files.

CHECK BLOB CHECKSUM;
****
+---------+-----------+-------+----------+-------+---------------------+----------------------------------------------------------------------------------------+---------------------------------------------------------------------------------------------------------------+
| node_id | Host      | Port  | Database | Table | Filename            | Reason                                                                                 | Repair operations                                                                                             |
+---------+-----------+-------+----------+-------+---------------------+----------------------------------------------------------------------------------------+---------------------------------------------------------------------------------------------------------------+
| 2       | 127.0.0.1 | 10001 | db3      | rtab  | blobs/22/0/0/10_29  | File has incorrect checksum. Actual checksum 0x29072b55, expected checksum 0xe6ac67b6. | copy blob file from replica on '127.0.0.1':10000                                                              |
| 2       | 127.0.0.1 | 10001 | db3      | rtab  | blobs/22/0/0/10_58  | Missing file                                                                           | copy blob file from replica on '127.0.0.1':10000                                                              |
| 2       | 127.0.0.1 | 10001 | db3      | rtab  | blobs/22/0/0/10_88  | File has incorrect size. Actual size 49, expected size 44                              | Remove file (a copy of the file is avaliable on 127.0.0.1:10000, but its not valid.  Hit error 1017)          |
| 2       | 127.0.0.1 | 10001 | db3      | rtab  | blobs/22/0/0/10_112 | File has incorrect size. Actual size 51, expected size 46                              | copy blob file from replica on '127.0.0.1':10000                                                              |
| 2       | 127.0.0.1 | 10001 | db3      | rtab  | blobs/22/0/0/10_118 | File has incorrect size. Actual size 49, expected size 44                              | copy blob file from replica on '127.0.0.1':10000                                                              |
| 2       | 127.0.0.1 | 10001 | db3      | rtab  | blobs/22/0/0/10_191 | Missing file                                                                           | copy blob file from replica on '127.0.0.1':10000                                                              |
| 2       | 127.0.0.1 | 10001 | db3      | rtab  | blobs/22/0/0/10_203 | File has incorrect checksum. Actual checksum 0xf6aac90f, expected checksum 0x390185ec. | copy blob file from replica on '127.0.0.1':10000                                                              |
| 2       | 127.0.0.1 | 10001 | db3      | rtab  | blobs/22/0/0/10_208 | Missing file                                                                           | copy blob file from replica on '127.0.0.1':10000                                                              |
| 2       | 127.0.0.1 | 10001 | db3      | rtab  | blobs/22/0/0/10_214 | File has incorrect checksum. Actual checksum 0x205df634, expected checksum 0xdb081c6a. | copy blob file from replica on '127.0.0.1':10000                                                              |
| 2       | 127.0.0.1 | 10001 | db3      | rtab  | blobs/22/0/0/10_232 | File has incorrect checksum. Actual checksum 0x460d1e1a, expected checksum 0xbbab2e04. | Remove file (a copy of the file is avaliable on 127.0.0.1:10000, but its not valid.  Hit error 1017)          |
| 2       | 127.0.0.1 | 10001 | db3      | rtab  | blobs/22/0/0/10_238 | File has incorrect checksum. Actual checksum 0x31705cf0, expected checksum 0xca25b6ae. | copy blob file from replica on '127.0.0.1':10000                                                              |

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