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ea0be9e2d6
Allow ALGORITHM=INSTANT (or avoid touching any data) when changing the collation, or in some cases, the character set, of a non-indexed CHAR or VARCHAR column. There is no penalty for subsequent DDL or DML operations, and compatibility with older MariaDB versions will be unaffected. Character sets may be changed when the old encoding is compatible with the new one. For example, changing from ASCII to anything ASCII-based, or from 3-byte to 4-byte UTF-8 can sometimes be performed instantly. This is joint work with Eugene Kosov. The test cases as well as ALTER_CONVERT_TO, charsets_are_compatible(), Type_handler::Charsets_are_compatible() are his work. The Field_str::is_equal(), Field_varstring::is_equal() and the InnoDB changes were mostly rewritten by me due to conflicts with MDEV-15563. Limitations: Changes of indexed columns will still require ALGORITHM=COPY. We should allow ALGORITHM=NOCOPY and allow the indexes to be rebuilt inside the storage engine, without copying the entire table. Instant column size changes (in bytes) are not supported by all storage engines. Instant CHAR column changes are only allowed for InnoDB ROW_FORMAT=REDUNDANT. We could allow this for InnoDB when the CHAR internally uses a variable-length encoding, say, when converting from 3-byte UTF-8 to 4-byte UTF-8. Instant VARCHAR column changes are allowed for InnoDB ROW_FORMAT=REDUNDANT, and for others only if the size in bytes does not change from 128..255 bytes to more than 256 bytes. Inside InnoDB, this slightly changes the way how MDEV-15563 works and fixes the result of the innodb.instant_alter_extend test. We change the way how ALTER_COLUMN_EQUAL_PACK_LENGTH_EXT is handled. All column extension, type changes and renaming now go through a common route, except when ctx->is_instant() is in effect, for example, instant ADD or DROP COLUMN has been initiated. Only in that case we will go through innobase_instant_try() and rewrite all column metadata. get_type(field, prtype, mtype, len): Convert a SQL data type into InnoDB column metadata. innobase_rename_column_try(): Remove the update of SYS_COLUMNS. innobase_rename_or_enlarge_column_try(): New function, replacing part of innobase_rename_column_try() and all of innobase_enlarge_column_try(). Also changes column types. innobase_rename_or_enlarge_columns_cache(): Also change the column type.
30 lines
889 B
Plaintext
30 lines
889 B
Plaintext
--- instant_alter_convert.result
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+++ instant_alter_convert,utf8.result
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@@ -37,7 +37,7 @@
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test.t check status OK
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call check_table('t');
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name mtype prtype len
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-a 2 800FE 200
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+a 13 2100FE 600
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# CHAR enlargement
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alter table t modify a char(220), algorithm=instant;
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select count(a) from t where a = @bigval;
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@@ -51,7 +51,7 @@
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test.t check status OK
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call check_table('t');
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name mtype prtype len
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-a 2 800FE 220
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+a 13 2100FE 660
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# Convert from VARCHAR to a bigger CHAR
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alter table t modify a varchar(200), algorithm=instant;
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ERROR 0A000: ALGORITHM=INSTANT is not supported. Reason: Cannot change column type INPLACE. Try ALGORITHM=COPY
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@@ -72,7 +72,7 @@
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test.t check status OK
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call check_table('t');
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name mtype prtype len
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-a 2 800FE 255
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+a 13 2100FE 765
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# BINARY/VARBINARY test
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create or replace table t (a varbinary(300));
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alter table t modify a binary(255), algorithm=instant;
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