Experts point out that all sorts of different lossless compression strategies work differently. Many of these include modeling the data for compression to evaluate how to cut down on the necessary storage space without affecting the reconstitution of the data set. The achievement of lossless compression works through sets of highly sophisticated algorithms. That’s because although the quality of the media may be affected, these formats will still be digestible and useful with some data loss. In contrast, for music, image or video, it may be acceptable to have some data loss after compression. Technologies like zip file utilities provide this kind of service, while unzipping files leads to fully reconstituted data sets. Table is of the data dictionary kind, concurrent reads are allowed, but writesĪre serialized, and reads are blocked by writes.A general way to think about lossless compression is that for many types of files, including executable programs and code modules, it’s absolutely imperative that all of the data in a compressed format is fully reconstructed when the compression is reversed. The compression dictionary is stored in a new system InnoDB table. The maximum supported dictionary length is 32506 bytes ( zlib limitation). Quoting is handled by regular SQL quoting. In other words, a, bb, ccc, a bb ccc, and abbccc will have String (a comma or any other character can be used as a delimiter although not It is possible to predefine a compression dictionary, which is a set of stringsĬompression dictionaries can be represented as a list of words in the form of a To achieve a better compression ratio on relatively small individual data items, Innodb_compressed_columns_threshold have been implemented. Two new variables: innodb_compressed_columns_zip_level and If there is a columnĬompression/decompression request in an ALTER TABLE, it is forced to the To decompress a column, specify a value other than COMPRESSED toĬOLUMN_FORMAT: FIXED, DYNAMIC, or DEFAULT. G BLOB GENERATED ALWAYS AS (a ) STORED COLUMN_FORMAT COMPRESSED WITH COMPRESSION_DICTIONARY numbers Unlike Oracle MySQL, compression is applicable to generated stored columns. COLUMN_FORMAT COMPRESSED, or ALTER TABLE. When altering a table and modifying a column to the compressed format: ALTER TABLE. If this modifier isĪpplied to an unsupported column type or storage engine, an error is returned. TEXT (including TINYTEXT, MEDUUMTEXT, LONGTEXT)Ī compressed column is declared by using the syntax that extends the existingĬOLUMN_FORMAT modifier: COLUMN_FORMAT COMPRESSED. The feature is limited to InnoDB/XtraDB storage engine and to columns of theīLOB (including TINYBLOB, MEDIUMBLOB, LONGBLOG) This feature is based on a patch provided by Weixiang Zhai. JSON or XML) using compression methods with staticĪ way to select columns in the table to compress (in contrast to the InnoDB Compression is done by using the zlibĪdditionally, it is possible to pre-define a set of strings for each compressedĬolumn to achieve a better compression ratio on relatively small individualĪ better compression ratio for text data which consists of a large number of ForĪll other purposes, the data type is identical to the one without the modifier, User-level SQL and InnoDB data compression, that causes the data stored in theĬolumn to be compressed on writing to storage and decompressed on reading. The per-column compression feature is a data type modifier, independent from List of variables introduced in Percona Server for MySQL 8.0 Percona Server for MySQL 8.0.30-22 Update () Migrate and removing the TokuDB storage engine Installing and configuring Percona Server for MySQL with ZenFS support Verify the encryption for tables, tablespaces, and schemasĭifferences between Percona MyRocks and Facebook MyRocks Use the Amazon Key Management Service (AWS KMS)Įncrypt Binary Log Files and Relay Log Files Using the Key Management Interoperability Protocol (KMIP) Use the keyring component or keyring plugin LDAP authentication plugin system variables Start transaction with consistent snapshot Limiting the disk space used by binary log files INFORMATION_SCHEMA.COMPRESSION_DICTIONARY_TABLES INFORMATION_SCHEMA.COMPRESSION_DICTIONARY Interaction with innodb_force_recovery variable Limit the estimation of records in a Query XtraDB performance improvements for I/O-bound highly-concurrent workloads Running Percona Server for MySQL in a Docker Container Upgrade from systems that use the MyRocks or TokuDB storage engine and partitioned tables Percona Server for MySQL in-place upgrading guide: from 5.7 to 8.0 Install Percona Server for MySQL from a source tarballĬompile Percona Server for MySQL 8.0 from source Percona Server for MySQL feature comparison List of features available in Percona Server for MySQL releases
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