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ea1b25046c
When updating a table with virtual BLOB columns, the following might happen: - an old record is read from the table, it has no virtual blob values - update_virtual_fields() is run, vcol blob gets its value into the record. But only a pointer to the value is in the table->record[0], the value is in Field_blob::value String (but it doesn't have to be! it can be in the record, if the column is just a copy of another columns: ... b VARCHAR, c BLOB AS (b) ...) - store_record(table,record[1]), old record now is in record[1] - fill_record() prepares new values in record[0], vcol blob is updated, new value replaces the old one in the Field_blob::value - now both record[1] and record[0] have a pointer that points to the *new* vcol blob value. Or record[1] has a pointer to nowhere if Field_blob::value had to realloc. To fix this I have introduced a new String object 'read_value' in Field_blob. When updating virtual columns when a row has been read, the allocated value is stored in 'read_value' instead of 'value'. The allocated blobs for the new row is stored in 'value' as before. I also made, as a safety precaution, the insert delayed handling of blobs more general by using value to store strings instead of the record. This ensures that virtual functions on delayed insert should work in as in the case of normal insert. Triggers are now properly updating the read, write and vcol maps for used fields. This means that we don't need VCOL_UPDATE_FOR_READ_WRITE anymore and there is no need for any other special handling of triggers in update_virtual_fields(). To be able to test how many times virtual fields are invoked, I also relaxed rules that one can use local (@) variables in DEFAULT and non persistent virtual field expressions. |
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