: This generates a 128-bit MD5 hash of the input string, returned as a varbinary value.
: Using sys.fn_sqlvarbasetostr is generally discouraged in production code because it is an undocumented internal function. A more standard approach in T-SQL is CONVERT(INT, HashBytes('MD5', '...'), 2) or directly casting the binary to an integer. : This generates a 128-bit MD5 hash of
: Distributing data rows into different "buckets" or shards by hashing a unique ID. : Distributing data rows into different "buckets" or
: This internal (undocumented) function converts the binary hash into its string representation (e.g., '0x792106533f84b730c64951a1ea702c78' ). Breaking Down the Code : This attempts to
The SQL expression you provided is a specific method used in SQL Server to generate a or "sharding key" from a string value (in this case, the string '1455985476' ). Breaking Down the Code
: This attempts to cast that hex string into a 4-byte integer. Because the hash is much larger than an integer, SQL Server typically truncates the value, often resulting in an arithmetic overflow or returning a signed integer based on the last 4 bytes of the hash. The Result
: Creating a non-obvious integer ID from a sensitive string.