innoDB compression


Does anybody know if there is a way to get some innoDB compression statistics? I have enabled it, but I'm not actually sure if it's working. My databases are taking more space than I imaged.
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"The current version of the InnoDB Plugin provides only a limited means to monitor the performance of compression at runtime. Overall application performance, CPU and i/o utilization and the size of disk files are the best indicators of how effective compression is for your application. "

" The InnoDB Plugin does include some Information Schema tables (see Example 6.1, Using the Compression Information Schema Tables) that reflect the internal use of memory and the rates of compression used overall. The INNODB_CMP tables report information about compression activity for each compressed page size (KEY_BLOCK_SIZE) in use. The information in these tables is system-wide, and includes summary data across all compressed tables in your database. You can use this data to help decide whether or not to compress a table by examining these tables when no other compressed tables are being accessed.

The key statistics to consider are the number of, and amount of time spent performing, compression and uncompression operations. Since InnoDB must split B-tree nodes when they are too full to contain the compressed data following a modification, you should also compare the number of successful compression operations with the number of such operations overall. Based on the information in the INNODB_CMP tables and overall application performance and hardware resource utilization, you may decide to make changes in your hardware configuration, adjust the size of the InnoDB buffer pool, choose a different page size, or select a different set of tables to compress.

If the amount of CPU time required for compressing and uncompressing is high, changing to faster CPUs, or those with more cores, can help improve performance with the same data, application workload and set of compressed tables. You may also benefit by increasing the size of the InnoDB buffer pool, so that more uncompressed pages can stay in memory, reducing the need to uncompress pages which exist in memory only in compressed form. "

3.4.2. Monitoring Compression at Runtime:

Based on this information, no direct stats you can use to get how compressions performs, however, using the key performance indicators mentioned in the above lines along with querying the system tables specified, you can figure-out how your compressions really works.

I hope this helps.
zattzAuthor Commented:
many thanks :)
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