Server System Variables Maximum Value 16384 This system variable is deprecated (because  DELAYED  inserts are not supported) and subject to removal in a future MySQL release. As of MySQL 8.0.26, setting the session value of this system variable is a restricted operation. The session user must have privileges sufficient to set restricted session variables. See Section 5.1.9.1, “System Variable Privileges” . • max_digest_length Command-Line Format --max-digest-length=# System Variable max_digest_length Scope Global Dynamic No SET_VAR  Hint Applies No Type Integer Default Value 1024 Minimum Value 0 Maximum Value 1048576 The maximum number of bytes of memory reserved per session for computation of normalized statement digests. Once that amount of space is used during digest computation, truncation occurs: no further tokens from a parsed statement are collected or figure into its digest value. Statements that differ only after that many bytes of parsed tokens produce the same normalized statement digest and are considered identical if compared or if aggregated for digest statistics. Setting  max_digest_length  to zero disables digest production, which also disables server functionality that requires digests, such as MySQL Enterprise Firewall. Warning Decreasing the  max_digest_length  value reduces memory use but causes the digest value of more statements to become indistinguishable if they differ only at the end. Increasing the value permits longer statements to be distinguished but increases memory use, particularly for workloads that involve large numbers of simultaneous sessions (the server allocates  max_digest_length  bytes per session). The parser uses this system variable as a limit on the maximum length of normalized statement digests that it computes. The Performance Schema, if it tracks statement digests, makes a copy of the digest value, using the  performance_schema_max_digest_length . system variable as a limit on the maximum length of digests that it stores. Consequently, if performance_schema_max_digest_length  is less than  max_digest_length , digest values stored in the Performance Schema are truncated relative to the original digest values. For more information about statement digesting, see Section 27.10, “Performance Schema Statement Digests and Sampling” . • max_error_count Command-Line Format --max-error-count=# 830