AliSQL: [Feature] Issue#30 SUPPORT BIG COLUMN COMPRESS

New syntax:

-----------

column_definition:

   data_type [NOT NULL | NULL] [DEFAULT default_value]

   [AUTO_INCREMENT] [UNIQUE [KEY] | [PRIMARY] KEY]

   [COMMENT 'string']

   [COLUMN_FORMAT

   {FIXED|DYNAMIC|COMPRESSED|DEFAULT}]

   [STORAGE {DISK|MEMORY|DEFAULT}]

   [reference_definition]

Description:

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If the column was defined as a compressed column, then the column data will be

compressed using zlib. Currently blob/text/varchar/varbinary are supported.

DDL:

Currently Not allowed to define a index that include compressed

column, an error message throw(ER_BLOB_KEY_WITH_COMPRESS)

And use COPY algorithm if column_format was changed. So we can't use

online ddl to change the column format.

Control option:

innodb_rds_column_compression_level

innodb_rds_column_zip_threshold

innodb_rds_column_zlib_strategy

        These variables above are used to control the param for deflate used by

        column data compression.

innodb_rds_column_zip_threshold

        control the compress threshold, if the data length exceeds this value,

        then compress the data.