First and foremost, I would like to extend my sincere thanks and appreciation for developing the Tedd.ShortUrl package! Here's an important issue I found.
Description of the Problem
The Tedd.ShortUrl package currently defines the Urls.Key column in the database with a case-insensitive collation by default. This design choice leads to an unintended reduction in the number of unique key combinations that can be generated, contrary to the assumptions set by the configuration.
Expected vs. Actual Behavior
The appsettings.json configuration file specifies a character set that includes both lowercase and uppercase letters: "23456789abcdefghjkmnpqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ". This suggests an intention for the system to treat keys with different cases as unique identifiers.
Expected Behavior: The system should allow for a vast number of unique combinations using the full character set, treating different cases as distinct.
Actual Behavior: Due to the case-insensitive collation, the system is currently unable to distinguish between keys that differ only by case, which greatly diminishes the number of possible unique keys.
Impact Analysis
Here is a comparison of the number of possible combinations when using a 5-character key under both case-sensitive and case-insensitive configurations:
5-character key with case sensitivity: 503,284,375 combinations
5-character key without case sensitivity: 33,554,432 combinations
This represents an approximate staggering reduction of 93% in the potential unique key space.
Real-World Implications
This reduction in key space has already manifested in practical terms, as evidenced by an issue reported here where duplicate keys were generated much sooner than statistically anticipated. This significantly increases the likelihood of key collisions, undermining the utility of the Tedd.ShortUrl service.
Workaround
To resolve this issue and align the database behavior with the intended configuration, the following SQL script changes can be applied manually after the table is created:
-- Drop the existing index if it exists
DROP INDEX IF EXISTS IX_Urls_Key ON dbo.Urls;
-- Alter the column to a case-sensitive collation
ALTER TABLE dbo.Urls
ALTER COLUMN [Key] nvarchar(10) COLLATE SQL_Latin1_General_CP1_CS_AS NOT NULL;
-- Recreate the unique index with the new collation
CREATE UNIQUE NONCLUSTERED INDEX [IX_Urls_Key] ON [dbo].[Urls]
(
[Key] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW LOCKS = ON, ALLOW_PAGE LOCKS = ON) ON [PRIMARY]
GO
These modifications will ensure the creation of the Key column with the necessary case sensitivity and will allow the application's character set to be fully leveraged, producing the expected number of unique short URL keys.
Long-term Solution
A better long-term solution would be to update the Entity Framework migrations to create the Key column with a case-sensitive collation by default.
Conclusion
Addressing this issue is crucial to maintaining the integrity and reliability of the Tedd.ShortUrl service. The current limitation poses a significant risk of key collisions and reduces the effectiveness of the system. Prompt implementation of the proposed solution is highly recommended.
First and foremost, I would like to extend my sincere thanks and appreciation for developing the Tedd.ShortUrl package! Here's an important issue I found.
Description of the Problem
The Tedd.ShortUrl package currently defines the
Urls.Keycolumn in the database with a case-insensitive collation by default. This design choice leads to an unintended reduction in the number of unique key combinations that can be generated, contrary to the assumptions set by the configuration.Expected vs. Actual Behavior
The
appsettings.jsonconfiguration file specifies a character set that includes both lowercase and uppercase letters:"23456789abcdefghjkmnpqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ". This suggests an intention for the system to treat keys with different cases as unique identifiers.Impact Analysis
Here is a comparison of the number of possible combinations when using a 5-character key under both case-sensitive and case-insensitive configurations:
This represents an approximate staggering reduction of 93% in the potential unique key space.
Real-World Implications
This reduction in key space has already manifested in practical terms, as evidenced by an issue reported here where duplicate keys were generated much sooner than statistically anticipated. This significantly increases the likelihood of key collisions, undermining the utility of the Tedd.ShortUrl service.
Workaround
To resolve this issue and align the database behavior with the intended configuration, the following SQL script changes can be applied manually after the table is created:
These modifications will ensure the creation of the Key column with the necessary case sensitivity and will allow the application's character set to be fully leveraged, producing the expected number of unique short URL keys.
Long-term Solution
A better long-term solution would be to update the Entity Framework migrations to create the Key column with a case-sensitive collation by default.
Conclusion
Addressing this issue is crucial to maintaining the integrity and reliability of the Tedd.ShortUrl service. The current limitation poses a significant risk of key collisions and reduces the effectiveness of the system. Prompt implementation of the proposed solution is highly recommended.