Details
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Task
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Status: Closed (View Workflow)
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Major
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Resolution: Fixed
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10.3.1-2
Description
Storage engine independent support for column compression.
TINYBLOB, BLOB, MEDIUMBLOB, LONGBLOB, TINYTEXT, TEXT, MEDIUMTEXT, LONGTEXT,
VARCHAR and VARBINARY columns can be compressed.
New COMPRESSED column attribute added:
COMPRESSED[=<compression_method>]
The only supported method currently is zlib. It is not possible to create index over compressed column.
CSV storage engine stores compressed field data uncompressed on disk.
Binary log stores compressed field data compressed on disk.
System variables added:
column_compression_threshold - Minimum column data length eligible for compression.
column_compression_zlib_level - zlib compression level (1 gives best speed, 9 gives best compression).
column_compression_zlib_strategy - The strategy parameter is used to tune the compression algorithm. Use the value DEFAULT_STRATEGY for normal data, FILTERED for data produced by a filter (or predictor), HUFFMAN_ONLY to force Huffman encoding only (no string match), or RLE to limit match distances to one (run-length encoding). Filtered data consists mostly of small values with a somewhat random distribution. In this case, the compression algorithm is tuned to compress them better. The effect of FILTERED is to force more Huffman coding and less string matching; it is somewhat intermediate between DEFAULT_STRATEGY and HUFFMAN_ONLY. RLE is designed to be almost as fast as HUFFMAN_ONLY, but give better compression for PNG image data. The strategy parameter only affects the compression ratio but not the correctness of the compressed output even if it is not set appropriately. FIXED prevents the use of dynamic Huffman codes, allowing for a simpler decoder for special applications.
column_compression_zlib_wrap - Generate zlib header and trailer and compute adler32 check value. It can be used with storage engines that don't provide data integrity verification to detect data corruption.
Status variables added:
Column_compressions - incremented every time field data is compressed.
Column_decompressions - incremented every time field data is decompressed.
Attachments
Issue Links
- causes
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MDEV-13857 Use the 10.2 libmariadb in 10.3
- Closed
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MDEV-24797 Column Compression - ERROR 1265 (01000): Data truncated for column
- Closed
- is blocked by
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MDEV-13540 Server crashes in copy or Assertion `0' failed in virtual Field* Field_varstring_compressed::new_key_field
- Closed
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MDEV-13541 Server crashes in next_breadth_first_tab or Assertion `0' failed in Field_varstring_compressed::new_key_field
- Closed
- relates to
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MDEV-13378 Mysqld crashes with COMPRESSED data types, when using partitions
- Closed
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MDEV-11381 AliSQL: [Feature] Issue#30 SUPPORT BIG COLUMN COMPRESS
- Closed
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MDEV-13359 Enable online ALTER TABLE for compressed columns
- Closed
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MDEV-13539 Latest revision of bb-10.3-svoj (big column compressed) does not compile
- Closed
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MDEV-13795 ALTER TABLE…DROP PRIMARY KEY, ADD PRIMARY KEY fails when VIRTUAL columns exist
- Closed