The Ultimate Guide to High Availability with MariaDB

CRC32C

MariaDB starting with 10.8

Introduced in MariaDB 10.8.0 to compute a cyclic redundancy check (CRC) value using the Castagnoli polynomial.

Syntax

CRC32C([par,]expr)

Description

MariaDB has always included a native unary function CRC32() that computes the CRC-32 of a string using the ISO 3309 polynomial that used by zlib and many others.

InnoDB and MyRocks use a different polynomial, which was implemented in SSE4.2 instructions that were introduced in the Intel Nehalem microarchitecture. This is commonly called CRC-32C (Castagnoli).

The CRC32C function uses the Castagnoli polynomial.

This allows SELECT…INTO DUMPFILE to be used for the creation of files with valid checksums, such as a logically empty InnoDB redo log file ib_logfile0 corresponding to a particular log sequence number.

The optional parameter allows the checksum to be computed in pieces: CRC32C('MariaDB')=CRC32C(CRC32C('Maria'),'DB').

Examples

SELECT CRC32C('MariaDB');
+-------------------+
| CRC32C('MariaDB') |
+-------------------+
|         809606978 |
+-------------------+

SELECT CRC32C(CRC32C('Maria'),'DB');
+------------------------------+
| CRC32C(CRC32C('Maria'),'DB') |
+------------------------------+
|                    809606978 |
+------------------------------+

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