db2表压缩分析

/*

db2表压缩分析

适用范围：DB29.5,DB29.7

*/

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-- 确认表范围

-- 查看前10表占用空间最大的表

SELECT * FROM syscat.tables

WHERE TABSCHEMA= 'user_schema'

ORDER BY npages DESC

FETCH FIRST 10 ROWS ONLY

-- 启用表压缩

ALTER TABLE user_table_name compress yes;

-- 行压缩率评估

-- 导出行压缩评估信息

db2 inspect rowcompestimate table name user_table_name schema user_schema results keep user_table_name_out;

-- 格式化输出文件格式，压缩比在50%以上时，建议启用表压缩

db2inspf user_table_name_out user_table_name_out.txt

-- 重组表

db2 reorg table user_table_name keepdictionary

-- 收集关于表和索引的当前统计信息

db2 RUNSTATS ON TABLE user_schema.user_table_name WITH DISTRIBUTION AND DETAILED INDEXES ALL

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-- 查看表压缩比

SELECT tabname, card, npages, compression, avgrowcompressionratio, avgrowsize, pctpagessaved

FROM syscat.tables

WHERE TABSCHEMA= 'DB2INST1'

AND COMPRESSION = 'R'

ORDER BY tabname

-- 表空间剩余空间计算

SELECT TBSP_NAME

, tbsp_total_pages * 16 /1024/1024 AS tbsp_total_size_g

, tbsp_usable_pages * 16 /1024/1024 AS tbsp_usable_size_g

, tbsp_used_pages * 16 /1024/1024 AS tbsp_used_size_g

, tbsp_free_pages * 16 /1024/1024 AS tbsp_free_size_g

FROM SYSIBMADM.SNAPTBSP_PART

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