<p>The ALTER TABLE ... COALESCE PARTITION statement was issued with zero partitions to remove, so MySQL raises error 1515.</p>
<p>MySQL Error 1515 ER_COALESCE_PARTITION_NO_PARTITION occurs when ALTER TABLE ... COALESCE PARTITION specifies 0 partitions. Provide a positive integer or change strategy to REORGANIZE or DROP PARTITION to resolve the issue.</p>
At least one partition must be coalesced
This runtime error appears when executing ALTER TABLE ... COALESCE PARTITION with a value of 0. MySQL expects at least one partition to be merged, and issuing 0 violates that rule.
The server halts the statement, returns SQLSTATE HY000, and shows the message At least one partition must be coalesced.
The most common trigger is dynamic SQL or procedural logic that calculates the number of partitions to coalesce and accidentally passes 0.
Manual execution can also fail when the DBA misunderstands that COALESCE PARTITION N removes N partitions, not sets the total partition count.
Supply a positive integer to COALESCE PARTITION. The integer must not exceed the current partition count minus one.
If you actually want to reset the partition layout without removing partitions, use REORGANIZE PARTITION or avoid COALESCE entirely.
Automated maintenance scripts often compute the target partition count. Add guards so the script skips ALTER TABLE when the result is 0.
In interactive sessions, double check with SHOW CREATE TABLE or information_schema.PARTITIONS to confirm the existing count before choosing a value.
Validate computed partition numbers in application code and stored procedures.
Monitor error logs and set up alerts in your observability stack or through Galaxy to catch failed ALTER statements quickly.
Error 1514 ER_ADD_PARTITION_SUBPARTITION triggers when ADD PARTITION is misused with subpartitions. Supply correct partition clauses.
Error 1517 ER_DROP_PARTITION_NOT_EXIST arises when you attempt to drop a partition that does not exist. Verify partition names first.
A maintenance script calculated zero partitions to merge and passed that result directly to COALESCE.
The DBA thought COALESCE PARTITION sets the number of partitions rather than removes them.
Prior operations already reduced the partition count, so further coalescing would remove all partitions, resulting in a 0 argument.
Occurs when DROP PARTITION references non-existent partitions. Validate names first.
Raised when adding subpartitions in unsupported contexts. Check partitioning mode.
Appears when partition numbers exceed the maximum allowed. Use sensible counts.
It removes the specified number of partitions, merging their data into the remaining ones.
Yes, but N must be total_partitions minus one. Attempting to remove all partitions yields another error.
InnoDB performs this as a blocking DDL in most MySQL versions. Plan a maintenance window.
Galaxy highlights partition DDL syntax, offers AI-driven SQL linting, and warns when COALESCE PARTITION 0 is detected before execution.
.avif)
.avif){kind=logo}
