I am adding full text search to already existing mysql tables that have primary auto incrementing key of id integer.

When I add the full text index I get a warning:

/*!50604 ALTER TABLE `phppos_additional_item_numbers` ADD FULLTEXT INDEX item_number_search (`item_number`)*/;      

Warning (Code 124): InnoDB rebuilding table to add column FTS_DOC_ID

I cannot simply refactor all my code to add a column FTS_DOC_ID to remove this warning. Is it bad to just allow this warning to happen?

1 Answer 1


Reading the manual it does not seem to be anything bad. MySQL just informs you about an additional action it had to do.

InnoDB uses a unique document identifier referred to as a Document ID (DOC_ID) to map words in the full-text index to document records where the word appears. The mapping requires an FTS_DOC_ID column on the indexed table. If an FTS_DOC_ID column is not defined, InnoDB automatically adds a hidden FTS_DOC_ID column when the full-text index is created.

If you preferred to not get the warning, then you would have to manage the column yourself which looks like a lot of work which is currently automated:

If you choose to define the FTS_DOC_ID column yourself, you are responsible for managing the column to avoid empty or duplicate values. FTS_DOC_ID values cannot be reused, which means FTS_DOC_ID values must be ever increasing.

One side effect of the actions producing this warning is that the table has to be rebuild - that might take some time for tables already containing many records. But the same will be true if you added the column yourself, so it does not make a difference for you.

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