<p>The server rejects a PARTITION BY expression that uses a disallowed or non-deterministic function.</p>
<p>MySQL Error 1564 ER_PARTITION_FUNCTION_IS_NOT_ALLOWED shows up when the partitioning expression contains a function the storage engine cannot guarantee as deterministic, such as NOW() or RAND(). Replace the function with an allowed deterministic expression or upgrade the engine to resolve the issue.</p>
This partition function is not allowed
MySQL triggers this error during CREATE TABLE, ALTER TABLE, or IMPORT when the PARTITION BY clause references a function that is not permitted in partitioning expressions. The server rejects the statement before any data is written.
Partitioning is implemented at the storage layer, so every expression must be deterministic, based only on columns in the same row, and stable across sessions. Any violation causes error 1564.
MySQL safeguards physical data placement. Non-deterministic functions such as NOW(), UUID(), RAND(), or user-defined functions could route the same row to different partitions at different times, corrupting the partition map.
Storage engines like InnoDB also disallow functions dependent on dynamic system variables or subqueries. Rejecting them up-front preserves consistency and query planner reliability.
Developers often upgrade schemas and forget to remove NOW() used for time-based sharding, or they try to partition on a generated column that calls DATE_FORMAT(). Importing older dumps from MyISAM into InnoDB can surface the error as well.
Cloud migrations reveal it when the target MySQL version enforces stricter rules than the source version.
Identify the illegal function, replace it with a permitted deterministic expression, and rerun the DDL. For time ranges, use TO_DAYS(order_date) or UNIX_TIMESTAMP(order_date) instead of DATE(order_date).
When upgrading legacy tables, create a compatible generated column that converts the value and partition on that column.
Design partition keys early, stick to pure column arithmetic or built-in conversions, test DDL on staging running the target MySQL version, and document allowed expressions in your Galaxy shared collection.
Galaxy’s AI copilot flags disallowed functions while you type, preventing the error before execution.
Error 1492 partition function not allowed in generated column, Error 1733 key part too long, and Error 1503 create table fails often appear in tandem during schema refactors.
Using NOW(), CURDATE(), or SYSDATE() inside PARTITION BY leads to unpredictable evaluation.
RAND(), UUID(), or UUID_SHORT() change between calls, violating partition stability.
UDFs are blocked because MySQL cannot inspect their determinism.
Partitioning must rely on the current row only; external data breaks that rule.
Occurs when a generated column itself calls a disallowed function.
Raised when partition key exceeds storage limits.
Appears if the table lacks a primary key while partitioning.
No. DATE() is nondeterministic because it depends on session time zone. Use TO_DAYS() or explicit integer conversion.
No. You must recreate or alter the table with compliant expressions before the upgrade.
Yes. Galaxy highlights partition functions and warns if a chosen expression is disallowed, reducing production errors.
Generated columns stored virtually add negligible overhead and keep partitions clean.
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