<p>Error 1727 is raised when an INSERT targets a table whose AUTO_INCREMENT column is not the first column in its primary key, making the statement unsafe for statement-based binlogging.</p>
<p>MySQL Error 1727 ER_BINLOG_UNSAFE_AUTOINC_NOT_FIRST appears when an AUTO_INCREMENT column is not the leading part of the primary key, making the statement unsafe for statement-based replication. Put the AUTO_INCREMENT column first in the primary key or switch to row-based logging to resolve.</p>
INSERT into autoincrement field which is not the first
MySQL throws error 1727 when a DML statement inserts into a table where the AUTO_INCREMENT column is not the first component of the table27s primary key. The server halts execution because such statements are unsafe for statement-based binary logging and can break replication consistency.
The error is only triggered when binlog_format is STATEMENT or MIXED. In ROW mode, the engine logs actual row images, so the position of the AUTO_INCREMENT column no longer matters.
The root cause is an AUTO_INCREMENT column defined after another key column within a composite primary key. During statement replay on a replica, concurrent inserts can generate different AUTO_INCREMENT values, leading to data divergence.
The same issue happens when a table without a primary key uses a unique index starting with a non-AUTO_INCREMENT column that still contains an AUTO_INCREMENT field later in the index.
Four reliable fixes exist. The safest is to reorder the primary key so that the AUTO_INCREMENT column appears first. Alternatively, change binlog_format to ROW, recreate the table with a surrogate key, or disable binary logging if replication is unnecessary.
Choose the solution that fits your availability requirements and operational standards. Always test in staging before applying to production.
Legacy schemas often place date or tenant_id before id in a primary key. Rebuilding the table with id as the leading column resolves the problem. Multitenant SaaS designs can instead keep tenant_id but move AUTO_INCREMENT to a surrogate column and create a separate unique index.
Bulk load jobs may trigger the error if SET SESSION binlog_format = STATEMENT is left in place. Switch to ROW for the session to complete the load safely.
Always define a surrogate AUTO_INCREMENT primary key as the first column. Keep business keys in secondary indexes. Use ROW binlogging in high-write environments to eliminate most replication safety errors.
Automate schema linting in CI pipelines. Galaxy27s SQL editor can highlight unsafe primary key definitions before deployment, preventing the error from ever reaching production.
Other binlog safety errors include ER_BINLOG_UNSAFE_STMT (1592) and ER_BINLOG_ROW_MODE_AND_STMT_ENGINE (1665). They are resolved by switching to ROW binlogging or rewriting the offending statement.
When a primary key begins with a tenant_id or timestamp column and the AUTO_INCREMENT field follows, MySQL flags the statement as unsafe.
A server configured with binlog_format=STATEMENT or MIXED exposes statement-level safety checks and raises error 1727.
If the only uniqueness guarantee comes from an index where the AUTO_INCREMENT column is not first, inserts are considered nondeterministic.
Data migration scripts that temporarily set STATEMENT logging without adjusting key order can trigger the error.
Raised when a nondeterministic function like UUID() is used under STATEMENT logging. Switching to ROW or removing the function resolves it.
Occurs when a statement manipulates tables that do not support row-based logging. Converting the storage engine or using STATEMENT format fixes it.
Triggered by INSERT IGNORE SELECT patterns that can produce different results on replicas. Use ROW logging or rewrite query.
No. Ignoring the error risks data divergence between master and replicas. Always fix the schema or switch to ROW binlogging.
ROW logging increases network and storage usage but often improves replication accuracy. Evaluate workload and monitor binary log size after the change.
Yes. Galaxy27s schema linting highlights AUTO_INCREMENT columns that are not first in the primary key, letting you fix the issue during code review.
Error 1727 exists in MySQL 5.5 and later. The same rules apply in MariaDB, though the error number may differ.
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