database/mariadb-columnstore-engine
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MCOL-1068 Improve compression_ratio() procedure

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* Uncompressed columns caused a miscalculation for compression ratio
* We now show a ratio such as 2:1 rather than a percentage
* compressed_data_size instead of file_size is used to show the
compression of actual data, ignoring the pre-allocated segment
This commit is contained in:
Andrew Hutchings
2017-12-01 19:32:35 +00:00
parent 7c2640fab0
commit b657938709
1 changed files with 1 additions and 1 deletions
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dbcon/mysql/columnstore_info.sql
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@@ -82,7 +82,7 @@ DROP PROCEDURE IF EXISTS `compression_ratio` //
CREATE PROCEDURE compression_ratio()
BEGIN
SELECT CONCAT((SELECT SUM(file_size) FROM information_schema.columnstore_files WHERE compressed_data_size IS NOT NULL) / (SELECT SUM(data_size) FROM information_schema.columnstore_extents) * 100, '%') COMPRESSION_RATIO;
SELECT CONCAT((SELECT SUM(data_size) FROM information_schema.columnstore_extents ce left join information_schema.columnstore_columns cc on ce.object_id = cc.object_id where compression_type='Snappy') / (SELECT SUM(compressed_data_size) FROM information_schema.columnstore_files WHERE compressed_data_size IS NOT NULL), ':1') COMPRESSION_RATIO;
END //
DELIMITER ;