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  1. MariaDB Server
  2. MDEV-32668

tables with UNIQUE blob columns cannot be alter_algorithm=INSTANT modified

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      create table test (t text,  unique index i(t));
      		 
      ALTER TABLE test  ADD COLUMN test INT NULL AFTER t;
      		 
      ERROR 1846 (0A000): ALGORITHM=INSTANT is not supported. Reason: INPLACE ADD or DROP of virtual columns cannot be combined with other ALTER TABLE actions. Try ALGORITHM=COPY

      While the unique index i doesn't take place in the later, it does prevent it from instantly happening.

      Early in the alter_table processing compare_keys_but_name compares the existing table key and the table keys in the new structure, and determines they are different.

      This is because:

      • the table_key got treated by re_setup_keyinfo_hash and had HA_NOSAME stripped from the table_key->flags.
      • comparing further down in the same function, the comparsion of parts fails as the new_part->field and fields aren't populated.

      This results in the ALTER TABLE considering the index to be different, and not allowing the ALGORITHM=INSTANT later.

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          is caused by

          Task - A task that needs to be done. MDEV-371 Unique indexes for blobs

          • Critical - Crashes, loss of data, severe memory leak.
          • Closed
          is duplicated by

          Bug - A problem which impairs or prevents the functions of the product. MDEV-17468 Avoid table rebuild on operations on generated columns

          • Major - Major loss of function.
          • Stalled
          relates to

          Task - A task that needs to be done. MDEV-11369 Instant add column for InnoDB

          • Major - Major loss of function.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-14341 Allow LOCK=NONE in table-rebuilding ALTER when indexed virtual columns exist

          • Major - Major loss of function.
          • Open

          Task - A task that needs to be done. MDEV-15562 Instant DROP COLUMN or changing the order of columns

          • Critical - Crashes, loss of data, severe memory leak.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-18790 Server crash in fields_in_hash_keyinfo after unsuccessful attempt to drop BLOB with long index

          • Major - Major loss of function.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. MDEV-20918 INSTANT algorithm doesn't work with unique HASH index

          • Major - Major loss of function.
          • Open
          links to

          Web Link reported on Reddit

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              nikitamalyavin Nikita Malyavin
              danblack Daniel Black
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                Created:
                Updated:

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