HASHTYPE accepts values of all zeroes
Details
| Detail name | Value |
|---|---|
| Changelog Number | 12960 |
| Type | Improvement |
| Status | Resolved |
| Fix Versions | Exasol 7.1.7 |
| Resolution Date | 2022-03-16 |
Improvement
The HASHTYPE data type now allows storing
- a hash value containing all zeros '000...000'
- the NULL value.
In the past, this special value '000...000' was mapped to the NULL value.
Migration
During the update:
- all HASHTYPE columns will automatically be migrated to the new storage representation of the HASHTYPE datatype.
- All indices on those columns will be recreated
- The statistics on the HASHTYPE columns will be dropped.
After the migration, the column sizes for the HASHTYPE columns will be larger than before the update.
Initially, query performance will be reduced until all statistics are recomputed (on query time)
Depending on how much HASHTYPE data has to be migrated to the new storage format, the update may take a while.
Changed behavior
The HASHTYPE is extended to allow zero hash values (e.g. ‘0000-0000’). During the update to this database version all HASHTYPE columns will be migrated to the new storage format. This migration may take a while, depending on the number of HASHTYPE values. The new format requires an extra byte per row, so will use more memory.
